1// Copyright 2016 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 !purego
6
7package aes
8
9import (
10	"crypto/cipher"
11	"crypto/internal/alias"
12)
13
14// Assert that aesCipherAsm implements the cbcEncAble and cbcDecAble interfaces.
15var _ cbcEncAble = (*aesCipherAsm)(nil)
16var _ cbcDecAble = (*aesCipherAsm)(nil)
17
18type cbc struct {
19	b  *aesCipherAsm
20	c  code
21	iv [BlockSize]byte
22}
23
24func (b *aesCipherAsm) NewCBCEncrypter(iv []byte) cipher.BlockMode {
25	var c cbc
26	c.b = b
27	c.c = b.function
28	copy(c.iv[:], iv)
29	return &c
30}
31
32func (b *aesCipherAsm) NewCBCDecrypter(iv []byte) cipher.BlockMode {
33	var c cbc
34	c.b = b
35	c.c = b.function + 128 // decrypt function code is encrypt + 128
36	copy(c.iv[:], iv)
37	return &c
38}
39
40func (x *cbc) BlockSize() int { return BlockSize }
41
42// cryptBlocksChain invokes the cipher message with chaining (KMC) instruction
43// with the given function code. The length must be a multiple of BlockSize (16).
44//
45//go:noescape
46func cryptBlocksChain(c code, iv, key, dst, src *byte, length int)
47
48func (x *cbc) CryptBlocks(dst, src []byte) {
49	if len(src)%BlockSize != 0 {
50		panic("crypto/cipher: input not full blocks")
51	}
52	if len(dst) < len(src) {
53		panic("crypto/cipher: output smaller than input")
54	}
55	if alias.InexactOverlap(dst[:len(src)], src) {
56		panic("crypto/cipher: invalid buffer overlap")
57	}
58	if len(src) > 0 {
59		cryptBlocksChain(x.c, &x.iv[0], &x.b.key[0], &dst[0], &src[0], len(src))
60	}
61}
62
63func (x *cbc) SetIV(iv []byte) {
64	if len(iv) != BlockSize {
65		panic("cipher: incorrect length IV")
66	}
67	copy(x.iv[:], iv)
68}
69