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// 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 (
"crypto/cipher"
"strconv"
)
// The AES block size in bytes.
const BlockSize = 16
// A cipher is an instance of AES encryption using a particular key.
type aesCipher struct {
enc []uint32
dec []uint32
}
type KeySizeError int
func (k KeySizeError) Error() string {
return "crypto/aes: invalid key size " + strconv.Itoa(int(k))
}
// 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 NewCipher(key []byte) (cipher.Block, error) {
k := len(key)
switch k {
default:
return nil, KeySizeError(k)
case 16, 24, 32:
break
}
n := k + 28
c := &aesCipher{make([]uint32, n), make([]uint32, n)}
expandKey(key, c.enc, c.dec)
return c, nil
}
func (c *aesCipher) BlockSize() int { return BlockSize }
func (c *aesCipher) Encrypt(dst, src []byte) {
encryptBlock(c.enc, dst, src)
}
func (c *aesCipher) Decrypt(dst, src []byte) {
decryptBlock(c.dec, dst, src)
}
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