KMAC HWIP Technical Specification

Overview

This document specifies the Keccak Message Authentication Code (KMAC) and Secure Hashing Algorithm 3 (SHA3) hardware IP functionality. This module conforms to the OpenTitan guideline for peripheral device functionality. See that document for integration overview within the broader OpenTitan top level system.

Features

  • Support for SHA3-224, 256, 384, 512, SHAKE[128, 256] and cSHAKE[128, 256]
  • Support byte-granularity on input message
  • Support 128b, 192b, 256b, 384b, 512b of the secret key length in KMAC mode
  • Support arbitrary output length for SHAKE, cSHAKE, KMAC
  • Support customization input string S, and function-name N up to 36 bytes total
  • 64b x 9 depth Message FIFO
  • 1600b of internal state (internally represented in two shares for 1st-order masking)
  • Performance goals of >= 72 Mb/s @ 100MHz (when entropy is available always)
    • SHA3-512: roughly 88 MB/s at most
    • SHA3-224: 160 MB/s at most
  • Implement 1st-order masked Keccak permutations for Side-Channel Analysis (SCA) protection

Description

The KMAC module is a Keccak based message authentication code generator to check the integrity of an incoming message and a signature signed with the same secret key. The secret key length can vary up to 512 bits.

The KMAC generates at most 1600 bits of the digest value at a time which can be read from the STATE memory region. There’s a way for the software to read more digest values by manually running the Keccak rounds. The details of the operation are described in the SHA3 specification, FIPS 202 known as sponge construction.

The KMAC HWIP also performs the SHA3 hash functions without the authentication, whose purpose is to check the correctness of the received message. The KMAC IP supports various SHA3 hashing functions including SHA3 Extended Output Function (XOF) known as SHAKE functions.

The KMAC HWIP implements a defense mechanism to deter SCA attacks. It is expected to protect against 1st order SCA attacks by implementing masked storage and Domain Oriented Masking (DOM) AND logic inside the Keccak function.

Theory of Operation

Block Diagram

The above figure shows the KMAC/SHA3 HWIP block diagram. The KMAC has register interfaces for SW to configure the module, initiate the hashing process, and acquire the result digest from the STATE memory region. It also has interfaces tot he KeyMgr to get the secret key (masked) and the message data. The interface to the KeyMgr is mainly for Key Derivative Functions (KDF).

As similar with HMAC, KMAC HWIP also has a message FIFO (MSG_FIFO) whose depth was determined based on a few criteria such as the register interface width, and its latency, the latency of hashing algorithm (Keccak). Based on the given criteria, the MSG_FIFO depth was determined to store the incoming message while the SHA3 core is in computation.

The MSG_FIFO has a packer in front. It packs any partial writes into the size of inernal datapath (64bit) and stores in MSG_FIFO. It gives some freedome to the software not requiring to align the messages. It also doesn’t need the message length information.

The fed messages go into the KMAC core regardless of KMAC enabled or not. But the KMAC core just forwards the messages to SHA3 core in case of KMAC disabled. KMAC core prepends the encoded secret key as described in the SHA3 Derived Functions specification. It is expected that the software writes the encoded output length at the end of the message. For KDF triggered by KeyMgr, the encoded output length is appended inside the KeyMgr interface module in KMAC HWIP.

The SHA3 core is the main Keccak processing module. It supports SHA3 hashing functions, SHAKE128, SHAKE256 extended output functions, and also cSHAKE128, cSHAKE256 functions in order to support KMAC operation. To support multiple hashing functions, it has the padding logic inside. The padding logic mainly pads the predefined bits at the end of the message and also performs pad10*1() function. If cSHAKE mode is set, the padding logic also prepends the encoded function name N and the customization string S prior to the incoming messages according to the spec requirements.

Both the internal state width and the masking of the Keccak core are configurable via compile-time Verilog parameters. By default, 1600 bits of internal state are used and stored in two shares (1st order masking). The masked Keccak core takes 3 clock cycles per round if sufficient entropy is available. If desired, the masking can be disabled and the internal state width can be reduced to 25, 50, or 100 bits at compile time.

Hardware Interface

Referring to the Comportable guideline for peripheral device functionality, the module kmac has the following hardware interfaces defined.

Primary Clock: clk_i

Other Clocks: clk_edn_i

Bus Device Interfaces (TL-UL): tl

Bus Host Interfaces (TL-UL): none

Peripheral Pins for Chip IO: none

Interrupts:

Interrupt NameDescription
kmac_done

KMAC/SHA3 absorbing has been completed

fifo_empty

Message FIFO empty condition

kmac_err

KMAC/SHA3 error occurred. ERR_CODE register shows the details

Security Alerts:

Alert NameDescription
fatal_fault

This fatal alert is triggered when a fatal TL-UL bus integrity fault is detected inside the KMAC unit.

Design Details

Keccak Round

A Keccak round implements the Keccak_f function described in the SHA3 specification. Keccak round logic in KMAC/SHA3 HWIP not only supports 1600 bit internal states but also all possible values {25, 50, 100, 200, 400, 800, 1600} based on a parameter Width. Keccak permutations in the specification allow arbitrary number of rounds. This module, however, supports Keccak_f which always runs 12 + 2*L rounds, where $$ L = log_2 {( {Width \over 25} )} $$ . For instance, 200 bits of internal state run 18 rounds. KMAC/SHA3 instantiates the Keccak round module with 1600 bit.

Keccak round logic has two phases inside. Theta, Rho, Pi functions are executed at the 1st phase. Chi and Iota functions run at the 2nd phase. If the compile-time Verilog parameter EnMasking is not set, the first phase and the second phase run at the same cycle.

If the masking feature is enabled, Keccak round logic stores the intermediate state after processing the 1st phase. The stored value are fed into the Chi function at the next cycle. Chi function implements Domain-Oriented Masking (DOM) ANDlogic inside to protect against the 1st order SCA attacks. The DOM AND logic needs entropy to disperse the power peaks. Chi function moves forward only when there is valid entropy.

The 2nd phase takes a least two cycles due to the intrinsic behavior of DOM AND logic. If the entropy is not ready, it may not complete the DOM AND. Processing a Keccak_f (1600 bit state) takes a total of 72 cycles (24 rounds X 3 cycles/round) including the 1st and 2nd phases.

If the masking compile time option is enabled, Keccak round logic requires an additional 1600 bit to store the state value partially inside DOM AND logic. In addition to that Keccak round logic needs two sets of the same Theta, Rho, and Pi functions. As a result, the masked Keccak round logic takes more than twice as much as area than the unmasked version of it.

Padding for Keccak

Padding logic supports SHA3/SHAKE/cSHAKE algorithms. cSHAKE needs the extra inputs for the Function-name N and the Customization string S. Other than that, SHA3, SHAKE, and cSHAKE share similar datapath inside the padding module except the last part added next to the end of the message. SHA3 adds 2'b 10, SHAKE adds 4'b 1111, cSHAKE adds 2'b00 then pad10*1() follows. All are little-endian values.

Interface between this padding logic and the MSG_FIFO follows the conventional FIFO interface. So prim_fifo_* can talk to the padding logic directly. This module talks to Keccak round logic with a more memory-like interface. The interface has an additional address signal on top of the valid, ready, and data signals.

The hashing process begins when the software issues the start command to !!CMD . If cSHAKE is enabled, the padding logic expands the prefix value (N || S above) into a block size. The block size is determined by the !!CFG.kstrength . If the value is 128, the block size will be 168 bytes. If it is 256, the block size will be 136 bytes. The expanded prefix value is transmitted to the Keccak round logic. After sending the block size, the padding logic triggers the Keccak round logic to run a full 24 rounds.

If the mode is not cSHAKE, or cSHAKE mode and the prefix block has been processed, the padding logic accepts the incoming message bitstream and forward the data to the Keccak round logic in a block granularity. The padding logic controls the data flow and makes the Keccak logic to run after sending a block size.

After the software writes the message bitstream, it should issue the Process command into !!CMD register. The padding logic, after receiving the Process command, appends proper ending bits with respect to the !!CFG.mode value. The logic writes 0 up to the block size to the Keccak round logic then ends with 1 at the end of the block.

After the Keccak round completes the last block, the padding logic asserts an absorbed signal to notify the software. The signal generates the kmac_done interrupt. At this point, the software is able to read the digest in !!STATE memory region. If the output length is greater than the Keccak block rate in SHAKE and cSHAKE mode, the software may run the Keccak round manually by issuing Run command to !!CMD register.

The software completes the operation by issuing Done command after reading the digest. The padding logic clears internal variables and goes back to Idle state.

Padding for KMAC

KMAC core prepends and appends additional bitstream on top of Keccak padding logic in SHA3 core. The NIST SP 800-185 defines KMAC[128,256](K, X, L, S) as a cSHAKE function. See the section 4.3 in NIST SP 800-185 for details. If KMAC is enabled, the software should configure !!CFG.mode to cSHAKE and the first six bytes of !!PREFIX to 0x01204B4D4143 (bigendian). The first six bytes of !!PREFIX represents the value of encode_string("KMAC").

The KMAC padding logic prepends a block containing the encoded secret key to the output message. The KMAC first sends the block of secret key then accepts the incoming message bitstream. At the end of the message, the software writes right_encode(output_length) to MSG_FIFO prior to issue Process command.

Message FIFO

The KMAC HWIP has a compile-time configurable depth message FIFO inside. The message FIFO receives incoming message bitstream regardless of its byte position in a word. Then it packs the partial message bytes into the internal 64 bit data width. After packing the data, the logic stores the data into the FIFO until the internal KMAC/SHA3 engine consumes the data.

The depth of the message FIFO is chosen to cover the throughput of the software or other producers such as DMA engine. The size of the message FIFO is enough to hold the incoming data while the SHA3 engine is processing the previous block. Details are in kmac_pkg::MsgFifoDepth parameter. Default design parameters assume the system characteristics as below:

  • kmac_pkg::RegLatency: The register write takes 5 cycles.
  • kmac_pkg::Sha3Latency: Keccak round latency takes 72 cycles, which is the masked version of the Keccak round.

The message FIFO does not generate the masked message data. Incoming message bistream is not sensitive to the leakage. So if the EnMasking parameter is set, the second share of the message bistream is zero. The secret key, however, is stored as masked form always.

Keccak State Access

After the Keccak round completes the KMAC/SHA3 operation, the contents of the Keccak state contain the digest value. The software can access the 1600 bit of the Keccak state directly through the window of the KMAC/SHA3 register.

If the compile-time parameter masking feature is enabled, the upper 256B of the window is the second share of the Keccak state. If not, the upper address space is zero value. The software reads both of the Keccak state shares and XORed in the software to get the unmasked digest value if masking feature is set.

The Keccak state is valid after the sponge absorbing process is completed. While in an idle state or in the sponge absorbing stage, the value is zero. This ensures that the logic does not expose the secret key XORed with the keccak_f results of the prefix to the software. In addition to that, the KMAC/SHA3 blocks the software access to the Keccak state when it processes the request from KeyMgr for Key Derivation Function (KDF).

KeyMgr Interface

KMAC/SHA3 HWIP has an option to receive the secret key from KeyMgr via sideload key interface. The software should set !!CFG.sideload to use the KeyMgr sideloaded key in SW-initiated KMAC operation. keymgr_pkg::hw_key_t defines the structure of the sideloaded key. KeyMgr provides the sideloaded key in two-share masked form regardless of the compile-time parameter EnMasking. If EnMasking is not defined, the KMAC merges the shared key to the unmasked form before uses the key.

KeyMgr may initiate the KMAC operation via the KeyMgr data interface keymgr_pkg::kmac_data_{req|rsp}_t. KeyMgr sends 64-bit data (MsgWidth) in a beat with the message strobe signal. The state machine inside the KeyMgr interface logic starts when it receives the first valid data. Because this logic sees the first valid data as an initiator, KeyMgr cannot run KDF with an empty message. After the logic switches to accept the message bitstream from KeyMgr, it forces the KMAC to use the sideloaded key as a secret key. Also it ignores the command issued from the software. Instead it generates the commands and sends them to the KMAC core.

The last beat of the KeyMgr data moves the state machine to append the encoded output length. The output length is the digest width, which is 256 bit. It means that the logic appends 0x020100 (little-endian) to the end of the message. The output data from this logic goes to MSG_FIFO. Because the MSG_FIFO handles un-aligned data inside, KeyMgr interface logic sends the encoded output length value in a separate beat.

After the encoded output length is pushed to the KMAC core, the interface logic issues a Process command to run the hashing logic.

After hashing operation is completed, KMAC does not raise a kmac_done interrupt; rather it triggers the done status in the KeyMgr data response channel. The result digest always comes in two shares. If the EnMasking parameter is not set, the second share is always zero.

Entropy Generator

This section explains the entropy generator inside the KMAC HWIP.

Entropy block

KMAC has an entropy generator to feed the random value while KMAC is processing the secret key block. The entropy generator fetches initial entropy from the Entropy Distribution Network (EDN) module. The prim_lfsr module in this entropy generator consumes the seed entropy from EDN.

Internal entropy size used in KMAC operation is the length of Keccak state, which is 1600 bit. However, EDN provides the entropy in much less size. Requesting multiple entropy to EDN module degrades the KMAC throughput. This module requests the entropy to EDN then expands the entropy to 1600 bit.

This module, at first, expands the generated random values to 320 bits by stacking the values in every cycle. Then the 320b of the entropy is duplicated into 1600bit. Internally, the module stores only 320bit of entropy. We choose 320bit to cover one plane (5x 64bit). No requirement of the entropy bit size exists. But we have decided to prepare the entropy size bigger than the security strength and also cover one plane (5x 64bit).

The module periodically refreshes the LFSR with the new entropy from EDN. The refresh does not block the internal entropy expansion operation.

Error Report

This section explains the errors KMAC HWIP raises during the hasing operations, their meanings, and the error handling process.

KMAC HWIP has the error checkers in its internal datapath. If the checkers detect errors, whether they are triggered by the SW mis-configure, or HW malfunctions, they report the error to ERR_CODE and raise an kmac_error interrupt. Each error code gives debugging information at the lower 24 bits of ERR_CODE.

Value Error Code Description
0x01 KeyNotValid In KMAC mode with the sideloaded key, the IP raises an error if the sideloaded secret key is not ready.
0x02 SwPushedMsgFifo MsgFifo is updated while not being in the Message Feed state.
0x03 SwIssuedCmdInAppActive SW issued a command while the application interface is being used
0x04 WaitTimerExpired EDN has not responded within the wait timer limit.
0x05 IncorrectEntropyMode When SW sets entropy_ready, the entropy_mode is neither SW nor EDN.
0x06 UnexpectedModeStrength SHA3 mode and Keccak Strength combination is not expected.
0x07 IncorrectFunctionName In KMAC mode, the PREFIX has the value other than encoded_string("KMAC")
0x08 SwCmdSequence SW does not follow the guided sequence, start -> process -> {run ->} done
0x80 Sha3Control SW may receive Sha3Control error along with SwCmdSequence error. Can be ignored.

KeyNotValid (0x01)

The KeyNotValid error is raised in the application interface module. When a KMAC application requests a hashing operation, the module checks if the sideloaded key is ready. If the key is not ready, the module reports KeyNotValid error and moves to dead-end state and waits the IP reset.

This error does not provide any additional information.

SwPushedMsgFifo (0x02)

The SwPushedMsgFifo error happens when the Message FIFO receives TL-UL transactions while the application interface is busy. The Message FIFO drops the request.

The IP reports the error with an info field.

Bits Name Description
[23:16] reserved all zero
[15:8] kmac_app_st KMAC_APP FSM state.
[7:0] mux_sel Current APP Mux selection. 0: None, 1: SW, 2: App

SwIssuedCmdInAppActive (0x03)

If the SW issues any commands while the application interface is being used, the module reports SwIssuedCmdInAppActive error. The received command does not affect the Application process. The request is dropped by the KMAC_APP module.

The lower 3 bits of ERR_CODE contains the received command from the SW.

WaitTimerExpired (0x04)

The SW may set the EDN wait timer to exit from EDN request state if the response from EDN takes long. If the timer expires, the module cancels the transaction and report the WaitTimerExpired error.

When this error happens, the state machine in KMAC_ENTROPY module moves to Wait state. In that state, it keeps using the pre-generated entropy and asserting the entropy valid signal. It asserts the entropy valid signal to complete the current hashing operation. If the module does not complete, or flush the pending operation, it creates the back pressure to the message FIFO. Then, the SW may not be able to access the KMAC IP at all, as the crossbar is stuck.

The SW may move the state machine to the reset state by issuing CFG.err_processed.

IncorrectEntropyMode (0x05)

If SW misconfigures the entropy mode and let the entropy module prepare the random data, the module reports IncorrectEntropyMode error. The state machine moves to Wait state after reporting the error.

The SW may move the state machine to the reset state by issuing CFG.err_processed.

UnexpectedModeStrength (0x06)

When the SW issues Start command, the KMAC_ERRCHK module checks the CFG.mode and CFG.kstrength. The KMAC HWIP assumes the combinations of two to be SHA3-224, SHA3-256, SHA3-384, SHA3-512, SHAKE-128, SHAKE-256, cSHAKE-128, and cSHAKE-256. If the combination of the mode and kstrength does not fall into above, the module reports the UnexpectedModeStrength error.

However, the KMAC HWIP proceeds the hashing operation as other combinations does not cause any malfunctions inside the IP. The SW may get the incorrect digest value.

IncorrectFunctionName (0x07)

If CFG.kmac_en is set and the SW issues the Start command, the KMAC_ERRCHK checks if the PREFIX has correct function name, encode_string("KMAC"). If the value does not match to the byte form of encode_string("KMAC") (0x4341_4D4B_2001), it reports the IncorrectFunctionName error.

As same as UnexpectedModeStrength error, this error does not block the hashing operation. The SW may get the incorrect signature value.

SwCmdSequence (0x08)

The KMAC_ERRCHK module checks the SW issued commands if it follows the guideline. If the SW issues the command that is not relavant to the current context, the module reports the SwCmdSequence error. The lower 3bits of the ERR_CODE contains the received command.

This error, however, does not stop the KMAC HWIP. The incorrect command is dropped at the following datapath, SHA3 core.

Programmers Guide

Initialization

The software can update the KMAC/SHA3 configurations only when the IP is in the idle state. The software should check !!STATUS.sha3_idle before updating the configurations. The software must first program !!CFG.msg_endianness and !!CFG.state_endianness at the initialization stage. These determine the byte order of incoming messages (msg_endianness) and the Keccak state output (state_endianness).

Software Initiated KMAC/SHA3 process

This section describes the expected software process to run the KMAC/SHA3 HWIP. At first, the software configures !!CFG.kmac_en for KMAC operation. If KMAC is enabled, the software should configure !!CFG.mode to cSHAKE and !!CFG.kstrength to 128 or 256 bit security strength. The software also updates !!PREFIX registers if cSHAKE mode is used. Current design does not convert cSHAKE mode to SHAKE even if !!PREFIX is empty string. It is the software’s responsiblity to change the !!CFG.mode to SHAKE in case of empty !!PREFIX. The KMAC/SHA3 HWIP uses !!PREFIX registers as it is. It means that the software should update !!PREFIX with encoded values.

If !!CFG.kmac_en is set, the software should update the secret key. The software prepares two shares of the secret key and selects its length in !!KEY_LEN then writes the shares of the secret key to !!KEY_SHARE0 and !!KEY_SHARE1 . The two shares of the secret key are the values that represent the secret key value when they are XORed together. The software can XOR the unmasked secret key with entropy. The XORed value is a share and the entropy used is the other share.

After configuring, the software notifies the KMAC/SHA3 engine to accept incoming messages by issuing Start command into !!CMD . If Start command is not issued, the incoming message is discarded. If KMAC is enabled, the software pushes the right_encode(output_length) value at the end of the message. For example, if the desired output length is 256 bit, the software writes 0x00020100 to MSG_FIFO.

After the software pushes all messages, it issues Process command to !!CMD for SHA3 engine to complete the sponge absorbing process. SHA3 hashing engine pads the incoming message as defined in the SHA3 specification.

After the SHA3 engine completes the sponge absorbing step, it generates kmac_done interrupt. Or the software can poll the !!STATUS.squeeze bit until it becomes 1. In this stage, the software may run the Keccak round manually.

If the desired digest length is greater than the Keccak rate, the software issues Run command for the Keccak round logic to run one full round after the software reads the current available Keccak state. At this stage, KMAC/SHA3 does not raise an interrupt when the Keccak round completes the software initiated manual run. The software should check !!STATUS.squeeze register field for the readiness of !!STATE value.

After the software reads all the digest values, it issues Done command to !!CMD register to clear the internal states. Done command clears the Keccak state, FSM in SHA3 and KMAC, and a few internal variables. Secret key and other software programmed values won’t be reset.

Endianness

This KMAC HWIP operates in little-endian. Internal SHA3 hashing engine receives in 64-bit granularity. The data written to SHA3 is assumed to be little endian.

The software may write/read the data in big-endian order if !!CFG.msg_endianness or !!CFG.state_endianness is set. If the endianness bit is 1, the data is assumed to be big-endian. So, the internal logic byte-swap the data. For example, when the software writes 0xDEADBEEF with endianness as 1, the logic converts it to 0xEFBEADDE then writes into MSG_FIFO.

The software managed secret key, and the prefix are always little-endian values. For example, if the software configures the function name N in KMAC operation, it writes encode_string("KMAC"). The encode_string("KMAC") represents 0x01 0x20 0x4b 0x4d 0x41 0x43 in byte order. The software writes 0x4d4b2001 into !!PREFIX0 and 0x????4341 into !!PREFIX1 . Upper 2 bytes can vary depending on the customization input string S.

KMAC/SHA3 context switching

This version of KMAC/SHA3 HWIP does not support the software context switching. A context switching scheme would allow software to save the current hashing engine state and initiate a new high priority hashing operation. It could restore the previous hashing state later and continue the operation.

Registers

kmac.INTR_STATE @ 0x0

Interrupt State Register

Reset default = 0x0, mask 0x7
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  kmac_err fifo_empty kmac_done
BitsTypeResetNameDescription
0rw1c0x0kmac_done

KMAC/SHA3 absorbing has been completed

1rw1c0x0fifo_empty

Message FIFO empty condition

2rw1c0x0kmac_err

KMAC/SHA3 error occurred. ERR_CODE register shows the details


kmac.INTR_ENABLE @ 0x4

Interrupt Enable Register

Reset default = 0x0, mask 0x7
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  kmac_err fifo_empty kmac_done
BitsTypeResetNameDescription
0rw0x0kmac_done

Enable interrupt when INTR_STATE.kmac_done is set.

1rw0x0fifo_empty

Enable interrupt when INTR_STATE.fifo_empty is set.

2rw0x0kmac_err

Enable interrupt when INTR_STATE.kmac_err is set.


kmac.INTR_TEST @ 0x8

Interrupt Test Register

Reset default = 0x0, mask 0x7
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  kmac_err fifo_empty kmac_done
BitsTypeResetNameDescription
0wo0x0kmac_done

Write 1 to force INTR_STATE.kmac_done to 1.

1wo0x0fifo_empty

Write 1 to force INTR_STATE.fifo_empty to 1.

2wo0x0kmac_err

Write 1 to force INTR_STATE.kmac_err to 1.


kmac.ALERT_TEST @ 0xc

Alert Test Register

Reset default = 0x0, mask 0x1
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  fatal_fault
BitsTypeResetNameDescription
0wo0x0fatal_fault

Write 1 to trigger one alert event of this kind.


kmac.CFG_REGWEN @ 0x10

Controls the configurability of CFG register.

Reset default = 0x1, mask 0x1

This register ensures the contents of CFG register cannot be changed by the software while the KMAC/SHA3 is in operation mode.

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  en
BitsTypeResetNameDescription
0ro0x1en

Configuration enable.


kmac.CFG @ 0x14

KMAC Configuration register.

Reset default = 0x0, mask 0x30b133f
Register enable = CFG_REGWEN

This register is updated when the hashing engine is in Idle. If the software updates the register while the engine computes, the updated value will be discarded.

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  err_processed entropy_ready   entropy_fast_process   entropy_mode
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  sideload   state_endianness msg_endianness   mode kstrength kmac_en
BitsTypeResetNameDescription
0rwxkmac_en

KMAC datapath enable.

If this bit is 1, the incoming message is processed in KMAC with the secret key.

3:1rwxkstrength

Hashing Strength

3 bit field to select the security strength of SHA3 hashing engine. If mode field is set to SHAKE or cSHAKE, only 128 and 256 strength can be selected. Other value will result error when hashing starts.

0L128

128 bit strength. Keccak rate is 1344 bit

1L224

224 bit strength. Keccak rate is 1152 bit

2L256

256 bit strength. Keccak rate is 1088 bit

3L384

384 bit strength. Keccak rate is 832 bit

4L512

512 bit strength. Keccak rate is 576 bit

Other values are reserved.

5:4rwxmode

Keccak hashing mode.

This module supports SHA3 main hashing algorithm and the part of its derived functions, SHAKE and cSHAKE with limitations. This field is to select the mode.

0SHA3

SHA3 hashing mode. It appends 2'b 10 to the end of msg

2SHAKE

SHAKE hashing mode. It appends 1111 to the end of msg

3cSHAKE

cSHAKE hashing mode. It appends 00 to the end of msg

Other values are reserved.

7:6Reserved
8rw0x0msg_endianness

Message Endianness.

If 1 then each individual multi-byte value, regardless of its alignment, written to MSG_FIFO will be added to the message in big-endian byte order. If 0, each value will be added to the message in little-endian byte order. A message written to MSG_FIFO one byte at a time will not be affected by this setting. From a hardware perspective byte swaps are performed on a TL-UL word granularity.

9rwxstate_endianness

State Endianness.

If 1 then each individual word in the STATE output register is converted to big-endian byte order. The order of the words in relation to one another is not changed. This setting does not affect how the state is interpreted during computation.

11:10Reserved
12rwxsideload

Sideloaded Key.

If 1, KMAC uses KeyMgr sideloaded key for SW initiated KMAC operation. KMAC uses the sideloaded key regardless of this configuration when KeyMgr initiates the KMAC operation for Key Derivation Function (KDF).

15:13Reserved
17:16rwxentropy_mode

Entropy Mode

Software selects the entropy source with this field. In EdnMode, the entropy generator sends requests to EDN to get the entropy. The received entropy is fed into internal LFSR.

In SwMode, the software should update the internal LFSR seed through ENTROPY_SEED_LOWER and ENTROPY_SEED_UPPER.

0idle_mode

At reset state, the entropy mode is Idle mode. It does not operate in this mode.

1edn_mode

Entropy generator module fetches entropy from EDN

2sw_mode

Software update the internal entropy via register interface

Other values are reserved.

18Reserved
19rwxentropy_fast_process

Entropy Fast process mode.

If 1, entropy logic uses garbage data while not processing the KMAC key block. It will re-use previous entropy value and will not expand the entropy when it is consumed. Only it refreshes the entropy while processing the secret key block.

23:20Reserved
24rwxentropy_ready

Entropy Ready status.

Software sets this field to allow the entropy generator in KMAC to fetch the entropy and run.

25rwxerr_processed

When error occurs and one of the state machine stays at Error handling state, SW may process the error based on ERR_CODE, then let FSM back to the reset state


kmac.CMD @ 0x18

KMAC/ SHA3 command register.

Reset default = 0x0, mask 0xf

This register is to control the KMAC to start accepting message, to process the message, and to manually run additional keccak rounds at the end. Only at certain stage, the CMD affects to the control logic. It follows the sequence of

start --> process --> {run if needed --> } done

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  cmd
BitsTypeResetNameDescription
3:0r0w1cxcmd

Issue a command to the KMAC/SHA3 IP. To prevent sw from writing multiple bits at once, the field is defined as enum.

1start

If writes 1 into this field when KMAC/SHA3 is in idle, KMAC/SHA3 begins its operation.

If the mode is cSHAKE, before receiving the message, the hashing logic processes Function name string N and customization input string S first. If KMAC mode is enabled, additionally it processes secret key block.

2process

If writes 1 into this field when KMAC/SHA3 began its operation and received the entire message, it computes the digest or signing.

4run

The run field is used in the sponge squeezing stage. It triggers the keccak round logic to run full 24 rounds. This is optional and used when software needs more digest bits than the keccak rate.

It only affects when the kmac/sha3 operation is completed.

8done

If writes 1 into this field when KMAC/SHA3 squeezing is completed. KMAC/SHA3 hashing engine clears internal variables and goes back to Idle state for next command.

Other values are reserved.


kmac.STATUS @ 0x1c

KMAC/SHA3 Status register.

Reset default = 0x4001, mask 0xdf07
31302928272625242322212019181716
 
1514131211109876543210
fifo_full fifo_empty   fifo_depth   sha3_squeeze sha3_absorb sha3_idle
BitsTypeResetNameDescription
0ro0x1sha3_idle

If 1, SHA3 hashing engine is in idle state.

1roxsha3_absorb

If 1, SHA3 is receiving message stream and processing it

2roxsha3_squeeze

If 1, SHA3 completes sponge absorbing stage. In this stage, SW can manually run the hashing engine.

7:3Reserved
12:8roxfifo_depth

Message FIFO entry count

13Reserved
14ro0x1fifo_empty

Message FIFO Empty indicator

15roxfifo_full

Message FIFO Full indicator


kmac.ENTROPY_PERIOD @ 0x20

Entropy Timer Periods.

Reset default = 0x0, mask 0xffffffff
Register enable = CFG_REGWEN
31302928272625242322212019181716
wait_timer
1514131211109876543210
entropy_timer
BitsTypeResetNameDescription
15:0rwxentropy_timer

Entropy period in clock cycles This register determines the refresh period. The value is the number of clock cycles. In every entropy period, the entropy generation logic in KMAC requests new entropy to EDN and feed the value into LFSR seed.

If 0, the entropy generation logic does not refresh its seed. The software manually updates the seed by writing into "ENTROPY_SEED" registers.

31:16rwxwait_timer

EDN request wait timer.

The entropy module in KMAC waits up to this field in clock cycles after it sends request to EDN module. If the timer expires, the entropy module moves to an error state and notifies to the system.

If 0, the entropy module waits the EDN response always. If EDN does not respond in this configuration, the software shall reset the IP.


kmac.ENTROPY_SEED_LOWER @ 0x24

Entropy Seed [31:0].

Reset default = 0x0, mask 0xffffffff
Register enable = CFG_REGWEN

Everytime when the software writes into this register, LFSR is reseeded with the value of {ENTROPY_SEED_UPPER, ENTROPY_SEED_LOWER}.

31302928272625242322212019181716
seed...
1514131211109876543210
...seed
BitsTypeResetNameDescription
31:0rwxseed

Seed [31:0]


kmac.ENTROPY_SEED_UPPER @ 0x28

Entropy Seed [63:32].

Reset default = 0x0, mask 0xffffffff
Register enable = CFG_REGWEN

Everytime when the software writes into ENTROPY_SEED_LOWER register, LFSR is reseeded with the value of {ENTROPY_SEED_UPPER, ENTROPY_SEED_LOWER}.

31302928272625242322212019181716
seed...
1514131211109876543210
...seed
BitsTypeResetNameDescription
31:0rwxseed

Seed [63:32]


kmac.KEY_SHARE0_0 @ 0x2c

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_0...
1514131211109876543210
...key_0
BitsTypeResetNameDescription
31:0woxkey_0

32-bit chunk of up-to 512-bit Secret Key


kmac.KEY_SHARE0_1 @ 0x30

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_1...
1514131211109876543210
...key_1
BitsTypeResetNameDescription
31:0woxkey_1

For KMAC1


kmac.KEY_SHARE0_2 @ 0x34

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_2...
1514131211109876543210
...key_2
BitsTypeResetNameDescription
31:0woxkey_2

For KMAC2


kmac.KEY_SHARE0_3 @ 0x38

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_3...
1514131211109876543210
...key_3
BitsTypeResetNameDescription
31:0woxkey_3

For KMAC3


kmac.KEY_SHARE0_4 @ 0x3c

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_4...
1514131211109876543210
...key_4
BitsTypeResetNameDescription
31:0woxkey_4

For KMAC4


kmac.KEY_SHARE0_5 @ 0x40

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_5...
1514131211109876543210
...key_5
BitsTypeResetNameDescription
31:0woxkey_5

For KMAC5


kmac.KEY_SHARE0_6 @ 0x44

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_6...
1514131211109876543210
...key_6
BitsTypeResetNameDescription
31:0woxkey_6

For KMAC6


kmac.KEY_SHARE0_7 @ 0x48

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_7...
1514131211109876543210
...key_7
BitsTypeResetNameDescription
31:0woxkey_7

For KMAC7


kmac.KEY_SHARE0_8 @ 0x4c

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_8...
1514131211109876543210
...key_8
BitsTypeResetNameDescription
31:0woxkey_8

For KMAC8


kmac.KEY_SHARE0_9 @ 0x50

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_9...
1514131211109876543210
...key_9
BitsTypeResetNameDescription
31:0woxkey_9

For KMAC9


kmac.KEY_SHARE0_10 @ 0x54

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_10...
1514131211109876543210
...key_10
BitsTypeResetNameDescription
31:0woxkey_10

For KMAC10


kmac.KEY_SHARE0_11 @ 0x58

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_11...
1514131211109876543210
...key_11
BitsTypeResetNameDescription
31:0woxkey_11

For KMAC11


kmac.KEY_SHARE0_12 @ 0x5c

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_12...
1514131211109876543210
...key_12
BitsTypeResetNameDescription
31:0woxkey_12

For KMAC12


kmac.KEY_SHARE0_13 @ 0x60

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_13...
1514131211109876543210
...key_13
BitsTypeResetNameDescription
31:0woxkey_13

For KMAC13


kmac.KEY_SHARE0_14 @ 0x64

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_14...
1514131211109876543210
...key_14
BitsTypeResetNameDescription
31:0woxkey_14

For KMAC14


kmac.KEY_SHARE0_15 @ 0x68

KMAC Secret Key

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_15...
1514131211109876543210
...key_15
BitsTypeResetNameDescription
31:0woxkey_15

For KMAC15


kmac.KEY_SHARE1_0 @ 0x6c

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_0...
1514131211109876543210
...key_0
BitsTypeResetNameDescription
31:0woxkey_0

32-bit chunk of up-to 512-bit Secret Key


kmac.KEY_SHARE1_1 @ 0x70

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_1...
1514131211109876543210
...key_1
BitsTypeResetNameDescription
31:0woxkey_1

For KMAC1


kmac.KEY_SHARE1_2 @ 0x74

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_2...
1514131211109876543210
...key_2
BitsTypeResetNameDescription
31:0woxkey_2

For KMAC2


kmac.KEY_SHARE1_3 @ 0x78

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_3...
1514131211109876543210
...key_3
BitsTypeResetNameDescription
31:0woxkey_3

For KMAC3


kmac.KEY_SHARE1_4 @ 0x7c

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_4...
1514131211109876543210
...key_4
BitsTypeResetNameDescription
31:0woxkey_4

For KMAC4


kmac.KEY_SHARE1_5 @ 0x80

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_5...
1514131211109876543210
...key_5
BitsTypeResetNameDescription
31:0woxkey_5

For KMAC5


kmac.KEY_SHARE1_6 @ 0x84

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_6...
1514131211109876543210
...key_6
BitsTypeResetNameDescription
31:0woxkey_6

For KMAC6


kmac.KEY_SHARE1_7 @ 0x88

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_7...
1514131211109876543210
...key_7
BitsTypeResetNameDescription
31:0woxkey_7

For KMAC7


kmac.KEY_SHARE1_8 @ 0x8c

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_8...
1514131211109876543210
...key_8
BitsTypeResetNameDescription
31:0woxkey_8

For KMAC8


kmac.KEY_SHARE1_9 @ 0x90

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_9...
1514131211109876543210
...key_9
BitsTypeResetNameDescription
31:0woxkey_9

For KMAC9


kmac.KEY_SHARE1_10 @ 0x94

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_10...
1514131211109876543210
...key_10
BitsTypeResetNameDescription
31:0woxkey_10

For KMAC10


kmac.KEY_SHARE1_11 @ 0x98

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_11...
1514131211109876543210
...key_11
BitsTypeResetNameDescription
31:0woxkey_11

For KMAC11


kmac.KEY_SHARE1_12 @ 0x9c

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_12...
1514131211109876543210
...key_12
BitsTypeResetNameDescription
31:0woxkey_12

For KMAC12


kmac.KEY_SHARE1_13 @ 0xa0

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_13...
1514131211109876543210
...key_13
BitsTypeResetNameDescription
31:0woxkey_13

For KMAC13


kmac.KEY_SHARE1_14 @ 0xa4

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_14...
1514131211109876543210
...key_14
BitsTypeResetNameDescription
31:0woxkey_14

For KMAC14


kmac.KEY_SHARE1_15 @ 0xa8

KMAC Secret Key, 2nd share.

Reset default = 0x0, mask 0xffffffff

KMAC secret key can be up to 512 bit. Order of the secret key is: key[512:0] = {KEY15, KEY14, ... , KEY0};

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

Current KMAC supports up to 512 bit secret key. It is the sw responsibility to keep upper bits of the secret key to 0.

31302928272625242322212019181716
key_15...
1514131211109876543210
...key_15
BitsTypeResetNameDescription
31:0woxkey_15

For KMAC15


kmac.KEY_LEN @ 0xac

Secret Key length in bit.

Reset default = 0x0, mask 0x7
Register enable = CFG_REGWEN

This value is used to make encoded secret key in KMAC. KMAC supports certain lengths of the secret key. Currently it supports 128b, 192b, 256b, 384b, and 512b secret keys.

31302928272625242322212019181716
 
1514131211109876543210
  len
BitsTypeResetNameDescription
2:0woxlen

Key length choice

0Key128

Key length is 128 bit.

1Key192

Key length is 192 bit.

2Key256

Key length is 256 bit.

3Key384

Key length is 384 bit.

4Key512

Key length is 512 bit.

Other values are reserved.


kmac.PREFIX_0 @ 0xb0

cSHAKE Prefix register.

Reset default = 0x0, mask 0xffffffff

Prefix including Function Name N and Customization String S. The SHA3 assumes this register value is encoded as: encode_string(N) || encode_string(S) || 0. It means that the software can freely decide the length of N or S based on the given Prefix register size 320bit. 320bit is determined to have 32-bit of N and up to 256-bit of S + encode of their length.

It is SW responsibility to fill the register with encoded value that is described at Section 2.3.2 String Encoding in NIST SP 800-185 specification.

Order of Prefix is: prefix[end:0] := {PREFIX(N-1), ..., PREFIX(1), PREFIX(0) }

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

31302928272625242322212019181716
prefix_0...
1514131211109876543210
...prefix_0
BitsTypeResetNameDescription
31:0rwxprefix_0

32-bit chunk of Encoded NS Prefix


kmac.PREFIX_1 @ 0xb4

cSHAKE Prefix register.

Reset default = 0x0, mask 0xffffffff

Prefix including Function Name N and Customization String S. The SHA3 assumes this register value is encoded as: encode_string(N) || encode_string(S) || 0. It means that the software can freely decide the length of N or S based on the given Prefix register size 320bit. 320bit is determined to have 32-bit of N and up to 256-bit of S + encode of their length.

It is SW responsibility to fill the register with encoded value that is described at Section 2.3.2 String Encoding in NIST SP 800-185 specification.

Order of Prefix is: prefix[end:0] := {PREFIX(N-1), ..., PREFIX(1), PREFIX(0) }

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

31302928272625242322212019181716
prefix_1...
1514131211109876543210
...prefix_1
BitsTypeResetNameDescription
31:0rwxprefix_1

For KMAC1


kmac.PREFIX_2 @ 0xb8

cSHAKE Prefix register.

Reset default = 0x0, mask 0xffffffff

Prefix including Function Name N and Customization String S. The SHA3 assumes this register value is encoded as: encode_string(N) || encode_string(S) || 0. It means that the software can freely decide the length of N or S based on the given Prefix register size 320bit. 320bit is determined to have 32-bit of N and up to 256-bit of S + encode of their length.

It is SW responsibility to fill the register with encoded value that is described at Section 2.3.2 String Encoding in NIST SP 800-185 specification.

Order of Prefix is: prefix[end:0] := {PREFIX(N-1), ..., PREFIX(1), PREFIX(0) }

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

31302928272625242322212019181716
prefix_2...
1514131211109876543210
...prefix_2
BitsTypeResetNameDescription
31:0rwxprefix_2

For KMAC2


kmac.PREFIX_3 @ 0xbc

cSHAKE Prefix register.

Reset default = 0x0, mask 0xffffffff

Prefix including Function Name N and Customization String S. The SHA3 assumes this register value is encoded as: encode_string(N) || encode_string(S) || 0. It means that the software can freely decide the length of N or S based on the given Prefix register size 320bit. 320bit is determined to have 32-bit of N and up to 256-bit of S + encode of their length.

It is SW responsibility to fill the register with encoded value that is described at Section 2.3.2 String Encoding in NIST SP 800-185 specification.

Order of Prefix is: prefix[end:0] := {PREFIX(N-1), ..., PREFIX(1), PREFIX(0) }

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

31302928272625242322212019181716
prefix_3...
1514131211109876543210
...prefix_3
BitsTypeResetNameDescription
31:0rwxprefix_3

For KMAC3


kmac.PREFIX_4 @ 0xc0

cSHAKE Prefix register.

Reset default = 0x0, mask 0xffffffff

Prefix including Function Name N and Customization String S. The SHA3 assumes this register value is encoded as: encode_string(N) || encode_string(S) || 0. It means that the software can freely decide the length of N or S based on the given Prefix register size 320bit. 320bit is determined to have 32-bit of N and up to 256-bit of S + encode of their length.

It is SW responsibility to fill the register with encoded value that is described at Section 2.3.2 String Encoding in NIST SP 800-185 specification.

Order of Prefix is: prefix[end:0] := {PREFIX(N-1), ..., PREFIX(1), PREFIX(0) }

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

31302928272625242322212019181716
prefix_4...
1514131211109876543210
...prefix_4
BitsTypeResetNameDescription
31:0rwxprefix_4

For KMAC4


kmac.PREFIX_5 @ 0xc4

cSHAKE Prefix register.

Reset default = 0x0, mask 0xffffffff

Prefix including Function Name N and Customization String S. The SHA3 assumes this register value is encoded as: encode_string(N) || encode_string(S) || 0. It means that the software can freely decide the length of N or S based on the given Prefix register size 320bit. 320bit is determined to have 32-bit of N and up to 256-bit of S + encode of their length.

It is SW responsibility to fill the register with encoded value that is described at Section 2.3.2 String Encoding in NIST SP 800-185 specification.

Order of Prefix is: prefix[end:0] := {PREFIX(N-1), ..., PREFIX(1), PREFIX(0) }

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

31302928272625242322212019181716
prefix_5...
1514131211109876543210
...prefix_5
BitsTypeResetNameDescription
31:0rwxprefix_5

For KMAC5


kmac.PREFIX_6 @ 0xc8

cSHAKE Prefix register.

Reset default = 0x0, mask 0xffffffff

Prefix including Function Name N and Customization String S. The SHA3 assumes this register value is encoded as: encode_string(N) || encode_string(S) || 0. It means that the software can freely decide the length of N or S based on the given Prefix register size 320bit. 320bit is determined to have 32-bit of N and up to 256-bit of S + encode of their length.

It is SW responsibility to fill the register with encoded value that is described at Section 2.3.2 String Encoding in NIST SP 800-185 specification.

Order of Prefix is: prefix[end:0] := {PREFIX(N-1), ..., PREFIX(1), PREFIX(0) }

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

31302928272625242322212019181716
prefix_6...
1514131211109876543210
...prefix_6
BitsTypeResetNameDescription
31:0rwxprefix_6

For KMAC6


kmac.PREFIX_7 @ 0xcc

cSHAKE Prefix register.

Reset default = 0x0, mask 0xffffffff

Prefix including Function Name N and Customization String S. The SHA3 assumes this register value is encoded as: encode_string(N) || encode_string(S) || 0. It means that the software can freely decide the length of N or S based on the given Prefix register size 320bit. 320bit is determined to have 32-bit of N and up to 256-bit of S + encode of their length.

It is SW responsibility to fill the register with encoded value that is described at Section 2.3.2 String Encoding in NIST SP 800-185 specification.

Order of Prefix is: prefix[end:0] := {PREFIX(N-1), ..., PREFIX(1), PREFIX(0) }

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

31302928272625242322212019181716
prefix_7...
1514131211109876543210
...prefix_7
BitsTypeResetNameDescription
31:0rwxprefix_7

For KMAC7


kmac.PREFIX_8 @ 0xd0

cSHAKE Prefix register.

Reset default = 0x0, mask 0xffffffff

Prefix including Function Name N and Customization String S. The SHA3 assumes this register value is encoded as: encode_string(N) || encode_string(S) || 0. It means that the software can freely decide the length of N or S based on the given Prefix register size 320bit. 320bit is determined to have 32-bit of N and up to 256-bit of S + encode of their length.

It is SW responsibility to fill the register with encoded value that is described at Section 2.3.2 String Encoding in NIST SP 800-185 specification.

Order of Prefix is: prefix[end:0] := {PREFIX(N-1), ..., PREFIX(1), PREFIX(0) }

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

31302928272625242322212019181716
prefix_8...
1514131211109876543210
...prefix_8
BitsTypeResetNameDescription
31:0rwxprefix_8

For KMAC8


kmac.PREFIX_9 @ 0xd4

cSHAKE Prefix register.

Reset default = 0x0, mask 0xffffffff

Prefix including Function Name N and Customization String S. The SHA3 assumes this register value is encoded as: encode_string(N) || encode_string(S) || 0. It means that the software can freely decide the length of N or S based on the given Prefix register size 320bit. 320bit is determined to have 32-bit of N and up to 256-bit of S + encode of their length.

It is SW responsibility to fill the register with encoded value that is described at Section 2.3.2 String Encoding in NIST SP 800-185 specification.

Order of Prefix is: prefix[end:0] := {PREFIX(N-1), ..., PREFIX(1), PREFIX(0) }

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

31302928272625242322212019181716
prefix_9...
1514131211109876543210
...prefix_9
BitsTypeResetNameDescription
31:0rwxprefix_9

For KMAC9


kmac.PREFIX_10 @ 0xd8

cSHAKE Prefix register.

Reset default = 0x0, mask 0xffffffff

Prefix including Function Name N and Customization String S. The SHA3 assumes this register value is encoded as: encode_string(N) || encode_string(S) || 0. It means that the software can freely decide the length of N or S based on the given Prefix register size 320bit. 320bit is determined to have 32-bit of N and up to 256-bit of S + encode of their length.

It is SW responsibility to fill the register with encoded value that is described at Section 2.3.2 String Encoding in NIST SP 800-185 specification.

Order of Prefix is: prefix[end:0] := {PREFIX(N-1), ..., PREFIX(1), PREFIX(0) }

The registers are allowed to be updated when the engine is in Idle state. If the engine computes the hash, it discards any attempts to update the secret keys and report an error.

31302928272625242322212019181716
prefix_10...
1514131211109876543210
...prefix_10
BitsTypeResetNameDescription
31:0rwxprefix_10

For KMAC10


kmac.ERR_CODE @ 0xdc

KMAC/SHA3 Error Code

Reset default = 0x0, mask 0xffffffff
31302928272625242322212019181716
err_code...
1514131211109876543210
...err_code
BitsTypeResetNameDescription
31:0roxerr_code

If error interrupt occurs, this register has information of error cause. Please take a look at `hw/ip/kmac/rtl/kmac_pkg.sv:err_code_e enum type.


kmac.STATE @ + 0x400
128 item ro window
Byte writes are not supported
310
+0x400 
+0x404 
 ...
+0x5f8 
+0x5fc 

Keccak State (1600 bit) memory.

The software can get the processed digest by reading this memory region. Unlike MSG_FIFO, STATE memory space sees the addr[9:0]. If Masking feature is enabled, the software reads two shares from this memory space.

0x400 - 0x4C7: State share 0x500 - 0x5C7: Mask share of the state, 0 if EnMasking = 0


kmac.MSG_FIFO @ + 0x800
512 item wo window
Byte writes are supported
310
+0x800 
+0x804 
 ...
+0xff8 
+0xffc 

Message FIFO.

Any write to this window will be appended to the FIFO. Only lower 2 bits [1:0] of the address matter to writes within the window in order to handle with sub-word writes.