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nobs/drbg/internal/aes/cipher.go
Kris Kwiatkowski 08f7315b64 DRBG: Speed improvements
* CTR-DRBG doesn't call "NewCipher" for block encryption
* Changes API of CTR-DRBG, so that read operation implementes io.Reader

Benchmark results:
----------------------
benchmark           old ns/op     new ns/op     delta
BenchmarkInit-4     1118          3579          +220.13%
BenchmarkRead-4     5343          14589         +173.05%

benchmark           old allocs     new allocs     delta
BenchmarkInit-4     15             0              -100.00%
BenchmarkRead-4     67             0              -100.00%

benchmark           old bytes     new bytes     delta
BenchmarkInit-4     1824          0             -100.00%
BenchmarkRead-4     9488          0             -100.00%
2019-04-09 14:37:59 +01:00

82 lines
1.8 KiB
Go

// Copyright 2009 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 (
"strconv"
)
// The AES block size in bytes.
const BlockSize = 16
// A cipher is an instance of AES encryption using a particular key.
type AES struct {
enc [32 + 28]uint32
dec [32 + 28]uint32
keyLen int
}
type KeySizeError int
func (k KeySizeError) Error() string {
return "crypto/aes: invalid key size " + strconv.Itoa(int(k))
}
func NewCipher() *AES {
return new(AES)
}
// NewCipher creates and returns a new cipher.Block.
// The key argument should be the AES key,
// either 16, 24, or 32 bytes to select
// AES-128, AES-192, or AES-256.
func (c *AES) SetKey(key []byte) error {
k := len(key)
switch k {
default:
return KeySizeError(k)
case 16, 24, 32:
break
}
for i, _ := range c.enc {
c.enc[i] = 0
}
for i, _ := range c.dec {
c.dec[i] = 0
}
c.keyLen = k
expandKeyGo(key, c.enc[:c.keyLen+28], c.dec[:c.keyLen+28])
return nil
}
func (c *AES) BlockSize() int { return BlockSize }
func (c *AES) 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 InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
panic("crypto/aes: invalid buffer overlap")
}
encryptBlockGo(c.enc[:c.keyLen+28], dst, src)
}
func (c *AES) 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 InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
panic("crypto/aes: invalid buffer overlap")
}
decryptBlockGo(c.dec[:c.keyLen+28], dst, src)
}