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// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build gc && !purego
package sha3
// This file contains code for using the 'compute intermediate
// message digest' (KIMD) and 'compute last message digest' (KLMD)
// instructions to compute SHA-3 and SHAKE hashes on IBM Z.
import (
"hash"
"golang.org/x/sys/cpu"
)
// codes represent 7-bit KIMD/KLMD function codes as defined in
// the Principles of Operation.
type code uint64
const (
// function codes for KIMD/KLMD
sha3_224 code = 32
sha3_256 = 33
sha3_384 = 34
sha3_512 = 35
shake_128 = 36
shake_256 = 37
nopad = 0x100
)
// kimd is a wrapper for the 'compute intermediate message digest' instruction.
// src must be a multiple of the rate for the given function code.
//
//go:noescape
func kimd(function code, chain *[200]byte, src []byte)
// klmd is a wrapper for the 'compute last message digest' instruction.
// src padding is handled by the instruction.
//
//go:noescape
func klmd(function code, chain *[200]byte, dst, src []byte)
type asmState struct {
a [200]byte // 1600 bit state
buf []byte // care must be taken to ensure cap(buf) is a multiple of rate
rate int // equivalent to block size
storage [3072]byte // underlying storage for buf
outputLen int // output length for full security
function code // KIMD/KLMD function code
state spongeDirection // whether the sponge is absorbing or squeezing
}
func newAsmState(function code) *asmState {
var s asmState
s.function = function
switch function {
case sha3_224:
s.rate = 144
s.outputLen = 28
case sha3_256:
s.rate = 136
s.outputLen = 32
case sha3_384:
s.rate = 104
s.outputLen = 48
case sha3_512:
s.rate = 72
s.outputLen = 64
case shake_128:
s.rate = 168
s.outputLen = 32
case shake_256:
s.rate = 136
s.outputLen = 64
default:
panic("sha3: unrecognized function code")
}
// limit s.buf size to a multiple of s.rate
s.resetBuf()
return &s
}
func (s *asmState) clone() *asmState {
c := *s
c.buf = c.storage[:len(s.buf):cap(s.buf)]
return &c
}
// copyIntoBuf copies b into buf. It will panic if there is not enough space to
// store all of b.
func (s *asmState) copyIntoBuf(b []byte) {
bufLen := len(s.buf)
s.buf = s.buf[:len(s.buf)+len(b)]
copy(s.buf[bufLen:], b)
}
// resetBuf points buf at storage, sets the length to 0 and sets cap to be a
// multiple of the rate.
func (s *asmState) resetBuf() {
max := (cap(s.storage) / s.rate) * s.rate
s.buf = s.storage[:0:max]
}
// Write (via the embedded io.Writer interface) adds more data to the running hash.
// It never returns an error.
func (s *asmState) Write(b []byte) (int, error) {
if s.state != spongeAbsorbing {
panic("sha3: Write after Read")
}
length := len(b)
for len(b) > 0 {
if len(s.buf) == 0 && len(b) >= cap(s.buf) {
// Hash the data directly and push any remaining bytes
// into the buffer.
remainder := len(b) % s.rate
kimd(s.function, &s.a, b[:len(b)-remainder])
if remainder != 0 {
s.copyIntoBuf(b[len(b)-remainder:])
}
return length, nil
}
if len(s.buf) == cap(s.buf) {
// flush the buffer
kimd(s.function, &s.a, s.buf)
s.buf = s.buf[:0]
}
// copy as much as we can into the buffer
n := len(b)
if len(b) > cap(s.buf)-len(s.buf) {
n = cap(s.buf) - len(s.buf)
}
s.copyIntoBuf(b[:n])
b = b[n:]
}
return length, nil
}
// Read squeezes an arbitrary number of bytes from the sponge.
func (s *asmState) Read(out []byte) (n int, err error) {
n = len(out)
// need to pad if we were absorbing
if s.state == spongeAbsorbing {
s.state = spongeSqueezing
// write hash directly into out if possible
if len(out)%s.rate == 0 {
klmd(s.function, &s.a, out, s.buf) // len(out) may be 0
s.buf = s.buf[:0]
return
}
// write hash into buffer
max := cap(s.buf)
if max > len(out) {
max = (len(out)/s.rate)*s.rate + s.rate
}
klmd(s.function, &s.a, s.buf[:max], s.buf)
s.buf = s.buf[:max]
}
for len(out) > 0 {
// flush the buffer
if len(s.buf) != 0 {
c := copy(out, s.buf)
out = out[c:]
s.buf = s.buf[c:]
continue
}
// write hash directly into out if possible
if len(out)%s.rate == 0 {
klmd(s.function|nopad, &s.a, out, nil)
return
}
// write hash into buffer
s.resetBuf()
if cap(s.buf) > len(out) {
s.buf = s.buf[:(len(out)/s.rate)*s.rate+s.rate]
}
klmd(s.function|nopad, &s.a, s.buf, nil)
}
return
}
// Sum appends the current hash to b and returns the resulting slice.
// It does not change the underlying hash state.
func (s *asmState) Sum(b []byte) []byte {
if s.state != spongeAbsorbing {
panic("sha3: Sum after Read")
}
// Copy the state to preserve the original.
a := s.a
// Hash the buffer. Note that we don't clear it because we
// aren't updating the state.
klmd(s.function, &a, nil, s.buf)
return append(b, a[:s.outputLen]...)
}
// Reset resets the Hash to its initial state.
func (s *asmState) Reset() {
for i := range s.a {
s.a[i] = 0
}
s.resetBuf()
s.state = spongeAbsorbing
}
// Size returns the number of bytes Sum will return.
func (s *asmState) Size() int {
return s.outputLen
}
// BlockSize returns the hash's underlying block size.
// The Write method must be able to accept any amount
// of data, but it may operate more efficiently if all writes
// are a multiple of the block size.
func (s *asmState) BlockSize() int {
return s.rate
}
// Clone returns a copy of the ShakeHash in its current state.
func (s *asmState) Clone() ShakeHash {
return s.clone()
}
// new224Asm returns an assembly implementation of SHA3-224 if available,
// otherwise it returns nil.
func new224Asm() hash.Hash {
if cpu.S390X.HasSHA3 {
return newAsmState(sha3_224)
}
return nil
}
// new256Asm returns an assembly implementation of SHA3-256 if available,
// otherwise it returns nil.
func new256Asm() hash.Hash {
if cpu.S390X.HasSHA3 {
return newAsmState(sha3_256)
}
return nil
}
// new384Asm returns an assembly implementation of SHA3-384 if available,
// otherwise it returns nil.
func new384Asm() hash.Hash {
if cpu.S390X.HasSHA3 {
return newAsmState(sha3_384)
}
return nil
}
// new512Asm returns an assembly implementation of SHA3-512 if available,
// otherwise it returns nil.
func new512Asm() hash.Hash {
if cpu.S390X.HasSHA3 {
return newAsmState(sha3_512)
}
return nil
}
// newShake128Asm returns an assembly implementation of SHAKE-128 if available,
// otherwise it returns nil.
func newShake128Asm() ShakeHash {
if cpu.S390X.HasSHA3 {
return newAsmState(shake_128)
}
return nil
}
// newShake256Asm returns an assembly implementation of SHAKE-256 if available,
// otherwise it returns nil.
func newShake256Asm() ShakeHash {
if cpu.S390X.HasSHA3 {
return newAsmState(shake_256)
}
return nil
}