main
1// Copyright 2017 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5//go:build gc && !purego
6
7package sha3
8
9// This file contains code for using the 'compute intermediate
10// message digest' (KIMD) and 'compute last message digest' (KLMD)
11// instructions to compute SHA-3 and SHAKE hashes on IBM Z.
12
13import (
14 "hash"
15
16 "golang.org/x/sys/cpu"
17)
18
19// codes represent 7-bit KIMD/KLMD function codes as defined in
20// the Principles of Operation.
21type code uint64
22
23const (
24 // function codes for KIMD/KLMD
25 sha3_224 code = 32
26 sha3_256 = 33
27 sha3_384 = 34
28 sha3_512 = 35
29 shake_128 = 36
30 shake_256 = 37
31 nopad = 0x100
32)
33
34// kimd is a wrapper for the 'compute intermediate message digest' instruction.
35// src must be a multiple of the rate for the given function code.
36//
37//go:noescape
38func kimd(function code, chain *[200]byte, src []byte)
39
40// klmd is a wrapper for the 'compute last message digest' instruction.
41// src padding is handled by the instruction.
42//
43//go:noescape
44func klmd(function code, chain *[200]byte, dst, src []byte)
45
46type asmState struct {
47 a [200]byte // 1600 bit state
48 buf []byte // care must be taken to ensure cap(buf) is a multiple of rate
49 rate int // equivalent to block size
50 storage [3072]byte // underlying storage for buf
51 outputLen int // output length for full security
52 function code // KIMD/KLMD function code
53 state spongeDirection // whether the sponge is absorbing or squeezing
54}
55
56func newAsmState(function code) *asmState {
57 var s asmState
58 s.function = function
59 switch function {
60 case sha3_224:
61 s.rate = 144
62 s.outputLen = 28
63 case sha3_256:
64 s.rate = 136
65 s.outputLen = 32
66 case sha3_384:
67 s.rate = 104
68 s.outputLen = 48
69 case sha3_512:
70 s.rate = 72
71 s.outputLen = 64
72 case shake_128:
73 s.rate = 168
74 s.outputLen = 32
75 case shake_256:
76 s.rate = 136
77 s.outputLen = 64
78 default:
79 panic("sha3: unrecognized function code")
80 }
81
82 // limit s.buf size to a multiple of s.rate
83 s.resetBuf()
84 return &s
85}
86
87func (s *asmState) clone() *asmState {
88 c := *s
89 c.buf = c.storage[:len(s.buf):cap(s.buf)]
90 return &c
91}
92
93// copyIntoBuf copies b into buf. It will panic if there is not enough space to
94// store all of b.
95func (s *asmState) copyIntoBuf(b []byte) {
96 bufLen := len(s.buf)
97 s.buf = s.buf[:len(s.buf)+len(b)]
98 copy(s.buf[bufLen:], b)
99}
100
101// resetBuf points buf at storage, sets the length to 0 and sets cap to be a
102// multiple of the rate.
103func (s *asmState) resetBuf() {
104 max := (cap(s.storage) / s.rate) * s.rate
105 s.buf = s.storage[:0:max]
106}
107
108// Write (via the embedded io.Writer interface) adds more data to the running hash.
109// It never returns an error.
110func (s *asmState) Write(b []byte) (int, error) {
111 if s.state != spongeAbsorbing {
112 panic("sha3: Write after Read")
113 }
114 length := len(b)
115 for len(b) > 0 {
116 if len(s.buf) == 0 && len(b) >= cap(s.buf) {
117 // Hash the data directly and push any remaining bytes
118 // into the buffer.
119 remainder := len(b) % s.rate
120 kimd(s.function, &s.a, b[:len(b)-remainder])
121 if remainder != 0 {
122 s.copyIntoBuf(b[len(b)-remainder:])
123 }
124 return length, nil
125 }
126
127 if len(s.buf) == cap(s.buf) {
128 // flush the buffer
129 kimd(s.function, &s.a, s.buf)
130 s.buf = s.buf[:0]
131 }
132
133 // copy as much as we can into the buffer
134 n := len(b)
135 if len(b) > cap(s.buf)-len(s.buf) {
136 n = cap(s.buf) - len(s.buf)
137 }
138 s.copyIntoBuf(b[:n])
139 b = b[n:]
140 }
141 return length, nil
142}
143
144// Read squeezes an arbitrary number of bytes from the sponge.
145func (s *asmState) Read(out []byte) (n int, err error) {
146 // The 'compute last message digest' instruction only stores the digest
147 // at the first operand (dst) for SHAKE functions.
148 if s.function != shake_128 && s.function != shake_256 {
149 panic("sha3: can only call Read for SHAKE functions")
150 }
151
152 n = len(out)
153
154 // need to pad if we were absorbing
155 if s.state == spongeAbsorbing {
156 s.state = spongeSqueezing
157
158 // write hash directly into out if possible
159 if len(out)%s.rate == 0 {
160 klmd(s.function, &s.a, out, s.buf) // len(out) may be 0
161 s.buf = s.buf[:0]
162 return
163 }
164
165 // write hash into buffer
166 max := cap(s.buf)
167 if max > len(out) {
168 max = (len(out)/s.rate)*s.rate + s.rate
169 }
170 klmd(s.function, &s.a, s.buf[:max], s.buf)
171 s.buf = s.buf[:max]
172 }
173
174 for len(out) > 0 {
175 // flush the buffer
176 if len(s.buf) != 0 {
177 c := copy(out, s.buf)
178 out = out[c:]
179 s.buf = s.buf[c:]
180 continue
181 }
182
183 // write hash directly into out if possible
184 if len(out)%s.rate == 0 {
185 klmd(s.function|nopad, &s.a, out, nil)
186 return
187 }
188
189 // write hash into buffer
190 s.resetBuf()
191 if cap(s.buf) > len(out) {
192 s.buf = s.buf[:(len(out)/s.rate)*s.rate+s.rate]
193 }
194 klmd(s.function|nopad, &s.a, s.buf, nil)
195 }
196 return
197}
198
199// Sum appends the current hash to b and returns the resulting slice.
200// It does not change the underlying hash state.
201func (s *asmState) Sum(b []byte) []byte {
202 if s.state != spongeAbsorbing {
203 panic("sha3: Sum after Read")
204 }
205
206 // Copy the state to preserve the original.
207 a := s.a
208
209 // Hash the buffer. Note that we don't clear it because we
210 // aren't updating the state.
211 switch s.function {
212 case sha3_224, sha3_256, sha3_384, sha3_512:
213 klmd(s.function, &a, nil, s.buf)
214 return append(b, a[:s.outputLen]...)
215 case shake_128, shake_256:
216 d := make([]byte, s.outputLen, 64)
217 klmd(s.function, &a, d, s.buf)
218 return append(b, d[:s.outputLen]...)
219 default:
220 panic("sha3: unknown function")
221 }
222}
223
224// Reset resets the Hash to its initial state.
225func (s *asmState) Reset() {
226 for i := range s.a {
227 s.a[i] = 0
228 }
229 s.resetBuf()
230 s.state = spongeAbsorbing
231}
232
233// Size returns the number of bytes Sum will return.
234func (s *asmState) Size() int {
235 return s.outputLen
236}
237
238// BlockSize returns the hash's underlying block size.
239// The Write method must be able to accept any amount
240// of data, but it may operate more efficiently if all writes
241// are a multiple of the block size.
242func (s *asmState) BlockSize() int {
243 return s.rate
244}
245
246// Clone returns a copy of the ShakeHash in its current state.
247func (s *asmState) Clone() ShakeHash {
248 return s.clone()
249}
250
251// new224 returns an assembly implementation of SHA3-224 if available,
252// otherwise it returns a generic implementation.
253func new224() hash.Hash {
254 if cpu.S390X.HasSHA3 {
255 return newAsmState(sha3_224)
256 }
257 return new224Generic()
258}
259
260// new256 returns an assembly implementation of SHA3-256 if available,
261// otherwise it returns a generic implementation.
262func new256() hash.Hash {
263 if cpu.S390X.HasSHA3 {
264 return newAsmState(sha3_256)
265 }
266 return new256Generic()
267}
268
269// new384 returns an assembly implementation of SHA3-384 if available,
270// otherwise it returns a generic implementation.
271func new384() hash.Hash {
272 if cpu.S390X.HasSHA3 {
273 return newAsmState(sha3_384)
274 }
275 return new384Generic()
276}
277
278// new512 returns an assembly implementation of SHA3-512 if available,
279// otherwise it returns a generic implementation.
280func new512() hash.Hash {
281 if cpu.S390X.HasSHA3 {
282 return newAsmState(sha3_512)
283 }
284 return new512Generic()
285}
286
287// newShake128 returns an assembly implementation of SHAKE-128 if available,
288// otherwise it returns a generic implementation.
289func newShake128() ShakeHash {
290 if cpu.S390X.HasSHA3 {
291 return newAsmState(shake_128)
292 }
293 return newShake128Generic()
294}
295
296// newShake256 returns an assembly implementation of SHAKE-256 if available,
297// otherwise it returns a generic implementation.
298func newShake256() ShakeHash {
299 if cpu.S390X.HasSHA3 {
300 return newAsmState(shake_256)
301 }
302 return newShake256Generic()
303}