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Diffstat (limited to 'src/crypto/aes/block.go')
| -rw-r--r-- | src/crypto/aes/block.go | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/src/crypto/aes/block.go b/src/crypto/aes/block.go new file mode 100644 index 0000000..53308ae --- /dev/null +++ b/src/crypto/aes/block.go @@ -0,0 +1,182 @@ +// 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. +// https://csrc.nist.gov/csrc/media/publications/fips/197/final/documents/fips-197.pdf +// https://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf + +package aes + +import ( + "encoding/binary" +) + +// Encrypt one block from src into dst, using the expanded key xk. +func encryptBlockGo(xk []uint32, dst, src []byte) { + _ = src[15] // early bounds check + s0 := binary.BigEndian.Uint32(src[0:4]) + s1 := binary.BigEndian.Uint32(src[4:8]) + s2 := binary.BigEndian.Uint32(src[8:12]) + s3 := binary.BigEndian.Uint32(src[12:16]) + + // 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 + var t0, t1, t2, t3 uint32 + for r := 0; r < nr; r++ { + t0 = xk[k+0] ^ te0[uint8(s0>>24)] ^ te1[uint8(s1>>16)] ^ te2[uint8(s2>>8)] ^ te3[uint8(s3)] + t1 = xk[k+1] ^ te0[uint8(s1>>24)] ^ te1[uint8(s2>>16)] ^ te2[uint8(s3>>8)] ^ te3[uint8(s0)] + t2 = xk[k+2] ^ te0[uint8(s2>>24)] ^ te1[uint8(s3>>16)] ^ te2[uint8(s0>>8)] ^ te3[uint8(s1)] + t3 = xk[k+3] ^ te0[uint8(s3>>24)] ^ te1[uint8(s0>>16)] ^ te2[uint8(s1>>8)] ^ te3[uint8(s2)] + 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[15] // early bounds check + binary.BigEndian.PutUint32(dst[0:4], s0) + binary.BigEndian.PutUint32(dst[4:8], s1) + binary.BigEndian.PutUint32(dst[8:12], s2) + binary.BigEndian.PutUint32(dst[12:16], s3) +} + +// Decrypt one block from src into dst, using the expanded key xk. +func decryptBlockGo(xk []uint32, dst, src []byte) { + _ = src[15] // early bounds check + s0 := binary.BigEndian.Uint32(src[0:4]) + s1 := binary.BigEndian.Uint32(src[4:8]) + s2 := binary.BigEndian.Uint32(src[8:12]) + s3 := binary.BigEndian.Uint32(src[12:16]) + + // 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 + var t0, t1, t2, t3 uint32 + for r := 0; r < nr; r++ { + t0 = xk[k+0] ^ td0[uint8(s0>>24)] ^ td1[uint8(s3>>16)] ^ td2[uint8(s2>>8)] ^ td3[uint8(s1)] + t1 = xk[k+1] ^ td0[uint8(s1>>24)] ^ td1[uint8(s0>>16)] ^ td2[uint8(s3>>8)] ^ td3[uint8(s2)] + t2 = xk[k+2] ^ td0[uint8(s2>>24)] ^ td1[uint8(s1>>16)] ^ td2[uint8(s0>>8)] ^ td3[uint8(s3)] + t3 = xk[k+3] ^ td0[uint8(s3>>24)] ^ td1[uint8(s2>>16)] ^ td2[uint8(s1>>8)] ^ td3[uint8(s0)] + 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[15] // early bounds check + binary.BigEndian.PutUint32(dst[0:4], s0) + binary.BigEndian.PutUint32(dst[4:8], s1) + binary.BigEndian.PutUint32(dst[8:12], s2) + binary.BigEndian.PutUint32(dst[12:16], 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 expandKeyGo(key []byte, enc, dec []uint32) { + // Encryption key setup. + var i int + nk := len(key) / 4 + for i = 0; i < nk; i++ { + enc[i] = binary.BigEndian.Uint32(key[4*i:]) + } + 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 = td0[sbox0[x>>24]] ^ td1[sbox0[x>>16&0xff]] ^ td2[sbox0[x>>8&0xff]] ^ td3[sbox0[x&0xff]] + } + dec[i+j] = x + } + } +} |