blob: e73335feb887d1c65b3ca27af66cc5fb3672db83 [file] [log] [blame]
// 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 (
"os";
"strconv";
)
// The AES block size in bytes.
const BlockSize = 16;
// A Cipher is an instance of AES encryption using a particular key.
type Cipher struct {
enc []uint32;
dec []uint32;
}
type KeySizeError int
func (k KeySizeError) String() string {
return "crypto/aes: invalid key size " + strconv.Itoa(int(k));
}
// NewCipher creates and returns a new Cipher.
// 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, os.Error) {
k := len(key);
switch k {
default:
return nil, KeySizeError(k);
case 16, 24, 32:
break;
}
n := k + 28;
c := &Cipher{make([]uint32, n), make([]uint32, n)};
expandKey(key, c.enc, c.dec);
return c, nil;
}
// BlockSize returns the AES block size, 16 bytes.
// It is necessary to satisfy the Key interface in the
// package "crypto/modes".
func (c *Cipher) BlockSize() int {
return BlockSize;
}
// Encrypt encrypts the 16-byte buffer src using the key k
// and stores the result in dst.
// Note that for amounts of data larger than a block,
// it is not safe to just call Encrypt on successive blocks;
// instead, use an encryption mode like AESCBC (see modes.go).
func (c *Cipher) Encrypt(src, dst []byte) {
encryptBlock(c.enc, src, dst);
}
// Decrypt decrypts the 16-byte buffer src using the key k
// and stores the result in dst.
func (c *Cipher) Decrypt(src, dst []byte) {
decryptBlock(c.dec, src, dst);
}
// Reset zeros the key data, so that it will no longer
// appear in the process's memory.
func (c *Cipher) Reset() {
for i := 0; i < len(c.enc); i++ {
c.enc[i] = 0;
}
for i := 0; i < len(c.dec); i++ {
c.dec[i] = 0;
}
}