Package: sha3_pkg

Description

Copyright lowRISC contributors.
Licensed under the Apache License, Version 2.0, see LICENSE for details.
SPDX-License-Identifier: Apache-2.0

sha3_pkg

Signals

Name Type Description
sha3_pkg endpackage

Constants

Name Type Value Description
StateW int 1600
FnWidth int 32 up to 32bit Function Name
CsWidth int 256 up to 256bit Customization Input
MaxFnEncodeSize int + 8 - 1 Calculate left_encode(len( X )) bit size. Assume the enc_8(n) is always 1 (up to 255 byte of len(S) size) e.g) 248bit --> two bytes , 256bit --> three bytes round8bit(clog2(X+1))/8
MaxCsEncodeSize int + 8 - 1
NSRegisterSizePre int FnWidth/8 + CsWidth/8
NSRegisterSize int 4 Round up to 32bit word base
PrefixSize int NSRegisterSize + 2 Prefix represents bytepad(encode_string(N)
PrefixIndexW int $clog2(PrefixSize/64) index width for N and S
MsgWidth int 64 Datapath width in KMAC, this also affects the output of MSG_FIFO This is assumed as 64 in KMAC design. If this value is changed, some parts of the KMAC design need to be changed.
1. keccak_round logic datapath. Keccak round logic assumes MsgWidth divides 1600 keccak state Width. Choose the value accordingly. 2. sha3pad module has fixed width mux for funcpad logic. If MsgWidth is changed, the logic also need to be revised. 3. kmac core logic also has fixed size mux for appeding output length. Revise the case statement to fit into revised MsgWidth value.
MsgStrbW int MsgWidth / 8
KeccakRate int unsigned undefined
MaxBlockSize int unsigned KeccakRate[0]
KeccakEntries int unsigned 1600/MsgWidth
KeccakMsgAddrW int unsigned $clog2(KeccakEntries)
KeccakCountW int unsigned $clog2(KeccakEntries+1)

Types

Name Type Description
sha3_mode_e enum logic[1:0] {
Sha3 = 2'b 00,
Shake = 2'b 10,
CShake = 2'b 11 }		 Keccak module supports SHA3, SHAKE, cSHAKE function. This mode determines if the module uses encoded N and S or not. Also it chooses the padding value.
mode
keccak_strength_e enum logic [2:0] {
L128 = 3'b 000,
L224 = 3'b 001,
L256 = 3'b 010,
L384 = 3'b 011,
L512 = 3'b 100 }		 keccak_strength_e determines the security strength against collision attack This value decides the rate and capacity of the keccak states. It affects the sha3pad module too. the padding module implements bytepad(X,168) for L128, bytepad(X,136) for L256 in cSHAKE
sha3_st_e enum logic [2:0] {
StIdle,
StAbsorb,
StSqueeze,
StManualRun,
StFlush }		 SHA3 core state. This state value is used in sha3core module and also in KMAC top module and the register interface for sw to track the sha3 status.
err_code_e enum logic [7:0] {
ErrNone = 8'h 00,
ErrSha3SwControl = 8'h 80 }		 //////////////// Error Report // ////////////////
err_t struct packed {
logic valid;
err_code_e code;
logic [23:0] info;
}

Functions

Description
/////////////
Functions //
/////////////
Bytepading function
encode_bytepad_len represents the first two bytes of bytepad()
It depends on the block size. We can reuse KeccakRate
10000000 || 00010101 // 168
10000000 || 00010001 // 136