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// Copyright 2016 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.
package aes
import (
"crypto/cipher"
"crypto/internal/subtle"
"internal/cpu"
)
type code int
// Function codes for the cipher message family of instructions.
const (
aes128 code = 18
aes192 = 19
aes256 = 20
)
type aesCipherAsm struct {
function code // code for cipher message instruction
key []byte // key (128, 192 or 256 bits)
storage [32]byte // array backing key slice
}
// cryptBlocks invokes the cipher message (KM) instruction with
// the given function code. This is equivalent to AES in ECB
// mode. The length must be a multiple of BlockSize (16).
//go:noescape
func cryptBlocks(c code, key, dst, src *byte, length int)
func newCipher(key []byte) (cipher.Block, error) {
// The aesCipherAsm type implements the cbcEncAble, cbcDecAble,
// ctrAble and gcmAble interfaces. We therefore need to check
// for all the features required to implement these modes.
// Keep in sync with crypto/tls/common.go.
if !(cpu.S390X.HasAES && cpu.S390X.HasAESCBC && cpu.S390X.HasAESCTR && (cpu.S390X.HasGHASH || cpu.S390X.HasAESGCM)) {
return newCipherGeneric(key)
}
var function code
switch len(key) {
case 128 / 8:
function = aes128
case 192 / 8:
function = aes192
case 256 / 8:
function = aes256
default:
return nil, KeySizeError(len(key))
}
var c aesCipherAsm
c.function = function
c.key = c.storage[:len(key)]
copy(c.key, key)
return &c, nil
}
func (c *aesCipherAsm) BlockSize() int { return BlockSize }
func (c *aesCipherAsm) Encrypt(dst, src []byte) {
if len(src) < BlockSize {
panic("crypto/aes: input not full block")
}
if len(dst) < BlockSize {
panic("crypto/aes: output not full block")
}
if subtle.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
panic("crypto/aes: invalid buffer overlap")
}
cryptBlocks(c.function, &c.key[0], &dst[0], &src[0], BlockSize)
}
func (c *aesCipherAsm) Decrypt(dst, src []byte) {
if len(src) < BlockSize {
panic("crypto/aes: input not full block")
}
if len(dst) < BlockSize {
panic("crypto/aes: output not full block")
}
if subtle.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
panic("crypto/aes: invalid buffer overlap")
}
// The decrypt function code is equal to the function code + 128.
cryptBlocks(c.function+128, &c.key[0], &dst[0], &src[0], BlockSize)
}
// expandKey is used by BenchmarkExpand. cipher message (KM) does not need key
// expansion so there is no assembly equivalent.
func expandKey(key []byte, enc, dec []uint32) {
expandKeyGo(key, enc, dec)
}
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