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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.
// This Go implementation is derived in part from the reference
// ANSI C implementation, which carries the following notice:
//
// rijndael-alg-fst.c
//
// @version 3.0 (December 2000)
//
// Optimised ANSI C code for the Rijndael cipher (now AES)
//
// @author Vincent Rijmen <vincent.rijmen@esat.kuleuven.ac.be>
// @author Antoon Bosselaers <antoon.bosselaers@esat.kuleuven.ac.be>
// @author Paulo Barreto <paulo.barreto@terra.com.br>
//
// This code is hereby placed in the public domain.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHORS ''AS IS'' AND ANY EXPRESS
// OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
// OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
// EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// See FIPS 197 for specification, and see Daemen and Rijmen's Rijndael submission
// for implementation details.
// http://www.csrc.nist.gov/publications/fips/fips197/fips-197.pdf
// http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf
package aes
import "crypto/aes"
// Encrypt one block from src into dst, using the expanded key xk.
func encryptBlock(xk []uint32, src, dst []byte) {
var s0, s1, s2, s3, t0, t1, t2, t3 uint32;
s0 = uint32(src[0])<<24 | uint32(src[1])<<16 | uint32(src[2])<<8 | uint32(src[3]);
s1 = uint32(src[4])<<24 | uint32(src[5])<<16 | uint32(src[6])<<8 | uint32(src[7]);
s2 = uint32(src[8])<<24 | uint32(src[9])<<16 | uint32(src[10])<<8 | uint32(src[11]);
s3 = uint32(src[12])<<24 | uint32(src[13])<<16 | uint32(src[14])<<8 | uint32(src[15]);
// First round just XORs input with key.
s0 ^= xk[0];
s1 ^= xk[1];
s2 ^= xk[2];
s3 ^= xk[3];
// Middle rounds shuffle using tables.
// Number of rounds is set by length of expanded key.
nr := len(xk)/4 - 2; // - 2: one above, one more below
k := 4;
for r := 0; r < nr; r++ {
t0 = xk[k+0] ^ te[0][s0>>24] ^ te[1][s1>>16 & 0xff] ^ te[2][s2>>8 & 0xff] ^ te[3][s3 & 0xff];
t1 = xk[k+1] ^ te[0][s1>>24] ^ te[1][s2>>16 & 0xff] ^ te[2][s3>>8 & 0xff] ^ te[3][s0 & 0xff];
t2 = xk[k+2] ^ te[0][s2>>24] ^ te[1][s3>>16 & 0xff] ^ te[2][s0>>8 & 0xff] ^ te[3][s1 & 0xff];
t3 = xk[k+3] ^ te[0][s3>>24] ^ te[1][s0>>16 & 0xff] ^ te[2][s1>>8 & 0xff] ^ te[3][s2 & 0xff];
k += 4;
s0, s1, s2, s3 = t0, t1, t2, t3;
}
// Last round uses s-box directly and XORs to produce output.
s0 = uint32(sbox0[t0>>24])<<24 | uint32(sbox0[t1>>16 & 0xff])<<16 | uint32(sbox0[t2>>8 & 0xff])<<8 | uint32(sbox0[t3 & 0xff]);
s1 = uint32(sbox0[t1>>24])<<24 | uint32(sbox0[t2>>16 & 0xff])<<16 | uint32(sbox0[t3>>8 & 0xff])<<8 | uint32(sbox0[t0 & 0xff]);
s2 = uint32(sbox0[t2>>24])<<24 | uint32(sbox0[t3>>16 & 0xff])<<16 | uint32(sbox0[t0>>8 & 0xff])<<8 | uint32(sbox0[t1 & 0xff]);
s3 = uint32(sbox0[t3>>24])<<24 | uint32(sbox0[t0>>16 & 0xff])<<16 | uint32(sbox0[t1>>8 & 0xff])<<8 | uint32(sbox0[t2 & 0xff]);
s0 ^= xk[k+0];
s1 ^= xk[k+1];
s2 ^= xk[k+2];
s3 ^= xk[k+3];
dst[0], dst[1], dst[2], dst[3] = byte(s0>>24), byte(s0>>16), byte(s0>>8), byte(s0);
dst[4], dst[5], dst[6], dst[7] = byte(s1>>24), byte(s1>>16), byte(s1>>8), byte(s1);
dst[8], dst[9], dst[10], dst[11] = byte(s2>>24), byte(s2>>16), byte(s2>>8), byte(s2);
dst[12], dst[13], dst[14], dst[15] = byte(s3>>24), byte(s3>>16), byte(s3>>8), byte(s3);
}
// Decrypt one block from src into dst, using the expanded key xk.
func decryptBlock(xk []uint32, src, dst []byte) {
var s0, s1, s2, s3, t0, t1, t2, t3 uint32;
s0 = uint32(src[0])<<24 | uint32(src[1])<<16 | uint32(src[2])<<8 | uint32(src[3]);
s1 = uint32(src[4])<<24 | uint32(src[5])<<16 | uint32(src[6])<<8 | uint32(src[7]);
s2 = uint32(src[8])<<24 | uint32(src[9])<<16 | uint32(src[10])<<8 | uint32(src[11]);
s3 = uint32(src[12])<<24 | uint32(src[13])<<16 | uint32(src[14])<<8 | uint32(src[15]);
// First round just XORs input with key.
s0 ^= xk[0];
s1 ^= xk[1];
s2 ^= xk[2];
s3 ^= xk[3];
// Middle rounds shuffle using tables.
// Number of rounds is set by length of expanded key.
nr := len(xk)/4 - 2; // - 2: one above, one more below
k := 4;
for r := 0; r < nr; r++ {
t0 = xk[k+0] ^ td[0][s0>>24] ^ td[1][s3>>16 & 0xff] ^ td[2][s2>>8 & 0xff] ^ td[3][s1 & 0xff];
t1 = xk[k+1] ^ td[0][s1>>24] ^ td[1][s0>>16 & 0xff] ^ td[2][s3>>8 & 0xff] ^ td[3][s2 & 0xff];
t2 = xk[k+2] ^ td[0][s2>>24] ^ td[1][s1>>16 & 0xff] ^ td[2][s0>>8 & 0xff] ^ td[3][s3 & 0xff];
t3 = xk[k+3] ^ td[0][s3>>24] ^ td[1][s2>>16 & 0xff] ^ td[2][s1>>8 & 0xff] ^ td[3][s0 & 0xff];
k += 4;
s0, s1, s2, s3 = t0, t1, t2, t3;
}
// Last round uses s-box directly and XORs to produce output.
s0 = uint32(sbox1[t0>>24])<<24 | uint32(sbox1[t3>>16 & 0xff])<<16 | uint32(sbox1[t2>>8 & 0xff])<<8 | uint32(sbox1[t1 & 0xff]);
s1 = uint32(sbox1[t1>>24])<<24 | uint32(sbox1[t0>>16 & 0xff])<<16 | uint32(sbox1[t3>>8 & 0xff])<<8 | uint32(sbox1[t2 & 0xff]);
s2 = uint32(sbox1[t2>>24])<<24 | uint32(sbox1[t1>>16 & 0xff])<<16 | uint32(sbox1[t0>>8 & 0xff])<<8 | uint32(sbox1[t3 & 0xff]);
s3 = uint32(sbox1[t3>>24])<<24 | uint32(sbox1[t2>>16 & 0xff])<<16 | uint32(sbox1[t1>>8 & 0xff])<<8 | uint32(sbox1[t0 & 0xff]);
s0 ^= xk[k+0];
s1 ^= xk[k+1];
s2 ^= xk[k+2];
s3 ^= xk[k+3];
dst[0], dst[1], dst[2], dst[3] = byte(s0>>24), byte(s0>>16), byte(s0>>8), byte(s0);
dst[4], dst[5], dst[6], dst[7] = byte(s1>>24), byte(s1>>16), byte(s1>>8), byte(s1);
dst[8], dst[9], dst[10], dst[11] = byte(s2>>24), byte(s2>>16), byte(s2>>8), byte(s2);
dst[12], dst[13], dst[14], dst[15] = byte(s3>>24), byte(s3>>16), byte(s3>>8), byte(s3);
}
// Apply sbox0 to each byte in w.
func subw(w uint32) uint32 {
return
uint32(sbox0[w>>24])<<24 |
uint32(sbox0[w>>16 & 0xff])<<16 |
uint32(sbox0[w>>8 & 0xff])<<8 |
uint32(sbox0[w & 0xff]);
}
// Rotate
func rotw(w uint32) uint32 {
return w<<8 | w>>24;
}
// Key expansion algorithm. See FIPS-197, Figure 11.
// Their rcon[i] is our powx[i-1] << 24.
func expandKey(key []byte, enc, dec []uint32) {
// Encryption key setup.
var i int;
nk := len(key) / 4;
for i = 0; i < nk; i++ {
enc[i] = uint32(key[4*i])<<24 | uint32(key[4*i+1])<<16 | uint32(key[4*i+2])<<8 | uint32(key[4*i+3]);
}
for ; i < len(enc); i++ {
t := enc[i-1];
if i % nk == 0 {
t = subw(rotw(t)) ^ (uint32(powx[i/nk - 1]) << 24);
} else if nk > 6 && i % nk == 4 {
t = subw(t);
}
enc[i] = enc[i-nk] ^ t;
}
// Derive decryption key from encryption key.
// Reverse the 4-word round key sets from enc to produce dec.
// All sets but the first and last get the MixColumn transform applied.
if dec == nil {
return;
}
n := len(enc);
for i := 0; i < n; i += 4 {
ei := n - i - 4;
for j := 0; j < 4; j++ {
x := enc[ei+j];
if i > 0 && i+4 < n {
x = td[0][sbox0[x>>24]] ^ td[1][sbox0[x>>16 & 0xff]] ^ td[2][sbox0[x>>8 & 0xff]] ^ td[3][sbox0[x & 0xff]];
}
dec[i+j] = x;
}
}
}
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