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Diffstat (limited to 'src/pkg/crypto/des/block.go')
| -rw-r--r-- | src/pkg/crypto/des/block.go | 223 |
1 files changed, 0 insertions, 223 deletions
diff --git a/src/pkg/crypto/des/block.go b/src/pkg/crypto/des/block.go deleted file mode 100644 index 26355a22e..000000000 --- a/src/pkg/crypto/des/block.go +++ /dev/null @@ -1,223 +0,0 @@ -// Copyright 2011 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 des - -import ( - "encoding/binary" -) - -func cryptBlock(subkeys []uint64, dst, src []byte, decrypt bool) { - b := binary.BigEndian.Uint64(src) - b = permuteInitialBlock(b) - left, right := uint32(b>>32), uint32(b) - - var subkey uint64 - for i := 0; i < 16; i++ { - if decrypt { - subkey = subkeys[15-i] - } else { - subkey = subkeys[i] - } - - left, right = right, left^feistel(right, subkey) - } - // switch left & right and perform final permutation - preOutput := (uint64(right) << 32) | uint64(left) - binary.BigEndian.PutUint64(dst, permuteFinalBlock(preOutput)) -} - -// Encrypt one block from src into dst, using the subkeys. -func encryptBlock(subkeys []uint64, dst, src []byte) { - cryptBlock(subkeys, dst, src, false) -} - -// Decrypt one block from src into dst, using the subkeys. -func decryptBlock(subkeys []uint64, dst, src []byte) { - cryptBlock(subkeys, dst, src, true) -} - -// DES Feistel function -func feistel(right uint32, key uint64) (result uint32) { - sBoxLocations := key ^ expandBlock(right) - var sBoxResult uint32 - for i := uint8(0); i < 8; i++ { - sBoxLocation := uint8(sBoxLocations>>42) & 0x3f - sBoxLocations <<= 6 - // row determined by 1st and 6th bit - // column is middle four bits - row := (sBoxLocation & 0x1) | ((sBoxLocation & 0x20) >> 4) - column := (sBoxLocation >> 1) & 0xf - sBoxResult ^= feistelBox[i][16*row+column] - } - return sBoxResult -} - -// feistelBox[s][16*i+j] contains the output of permutationFunction -// for sBoxes[s][i][j] << 4*(7-s) -var feistelBox [8][64]uint32 - -// general purpose function to perform DES block permutations -func permuteBlock(src uint64, permutation []uint8) (block uint64) { - for position, n := range permutation { - bit := (src >> n) & 1 - block |= bit << uint((len(permutation)-1)-position) - } - return -} - -func init() { - for s := range sBoxes { - for i := 0; i < 4; i++ { - for j := 0; j < 16; j++ { - f := uint64(sBoxes[s][i][j]) << (4 * (7 - uint(s))) - f = permuteBlock(uint64(f), permutationFunction[:]) - feistelBox[s][16*i+j] = uint32(f) - } - } - } -} - -// expandBlock expands an input block of 32 bits, -// producing an output block of 48 bits. -func expandBlock(src uint32) (block uint64) { - // rotate the 5 highest bits to the right. - src = (src << 5) | (src >> 27) - for i := 0; i < 8; i++ { - block <<= 6 - // take the 6 bits on the right - block |= uint64(src) & (1<<6 - 1) - // advance by 4 bits. - src = (src << 4) | (src >> 28) - } - return -} - -// permuteInitialBlock is equivalent to the permutation defined -// by initialPermutation. -func permuteInitialBlock(block uint64) uint64 { - // block = b7 b6 b5 b4 b3 b2 b1 b0 (8 bytes) - b1 := block >> 48 - b2 := block << 48 - block ^= b1 ^ b2 ^ b1<<48 ^ b2>>48 - - // block = b1 b0 b5 b4 b3 b2 b7 b6 - b1 = block >> 32 & 0xff00ff - b2 = (block & 0xff00ff00) - block ^= b1<<32 ^ b2 ^ b1<<8 ^ b2<<24 // exchange b0 b4 with b3 b7 - - // block is now b1 b3 b5 b7 b0 b2 b4 b7, the permutation: - // ... 8 - // ... 24 - // ... 40 - // ... 56 - // 7 6 5 4 3 2 1 0 - // 23 22 21 20 19 18 17 16 - // ... 32 - // ... 48 - - // exchange 4,5,6,7 with 32,33,34,35 etc. - b1 = block & 0x0f0f00000f0f0000 - b2 = block & 0x0000f0f00000f0f0 - block ^= b1 ^ b2 ^ b1>>12 ^ b2<<12 - - // block is the permutation: - // - // [+8] [+40] - // - // 7 6 5 4 - // 23 22 21 20 - // 3 2 1 0 - // 19 18 17 16 [+32] - - // exchange 0,1,4,5 with 18,19,22,23 - b1 = block & 0x3300330033003300 - b2 = block & 0x00cc00cc00cc00cc - block ^= b1 ^ b2 ^ b1>>6 ^ b2<<6 - - // block is the permutation: - // 15 14 - // 13 12 - // 11 10 - // 9 8 - // 7 6 - // 5 4 - // 3 2 - // 1 0 [+16] [+32] [+64] - - // exchange 0,2,4,6 with 9,11,13,15: - b1 = block & 0xaaaaaaaa55555555 - block ^= b1 ^ b1>>33 ^ b1<<33 - - // block is the permutation: - // 6 14 22 30 38 46 54 62 - // 4 12 20 28 36 44 52 60 - // 2 10 18 26 34 42 50 58 - // 0 8 16 24 32 40 48 56 - // 7 15 23 31 39 47 55 63 - // 5 13 21 29 37 45 53 61 - // 3 11 19 27 35 43 51 59 - // 1 9 17 25 33 41 49 57 - return block -} - -// permuteInitialBlock is equivalent to the permutation defined -// by finalPermutation. -func permuteFinalBlock(block uint64) uint64 { - // Perform the same bit exchanges as permuteInitialBlock - // but in reverse order. - b1 := block & 0xaaaaaaaa55555555 - block ^= b1 ^ b1>>33 ^ b1<<33 - - b1 = block & 0x3300330033003300 - b2 := block & 0x00cc00cc00cc00cc - block ^= b1 ^ b2 ^ b1>>6 ^ b2<<6 - - b1 = block & 0x0f0f00000f0f0000 - b2 = block & 0x0000f0f00000f0f0 - block ^= b1 ^ b2 ^ b1>>12 ^ b2<<12 - - b1 = block >> 32 & 0xff00ff - b2 = (block & 0xff00ff00) - block ^= b1<<32 ^ b2 ^ b1<<8 ^ b2<<24 - - b1 = block >> 48 - b2 = block << 48 - block ^= b1 ^ b2 ^ b1<<48 ^ b2>>48 - return block -} - -// creates 16 28-bit blocks rotated according -// to the rotation schedule -func ksRotate(in uint32) (out []uint32) { - out = make([]uint32, 16) - last := in - for i := 0; i < 16; i++ { - // 28-bit circular left shift - left := (last << (4 + ksRotations[i])) >> 4 - right := (last << 4) >> (32 - ksRotations[i]) - out[i] = left | right - last = out[i] - } - return -} - -// creates 16 56-bit subkeys from the original key -func (c *desCipher) generateSubkeys(keyBytes []byte) { - // apply PC1 permutation to key - key := binary.BigEndian.Uint64(keyBytes) - permutedKey := permuteBlock(key, permutedChoice1[:]) - - // rotate halves of permuted key according to the rotation schedule - leftRotations := ksRotate(uint32(permutedKey >> 28)) - rightRotations := ksRotate(uint32(permutedKey<<4) >> 4) - - // generate subkeys - for i := 0; i < 16; i++ { - // combine halves to form 56-bit input to PC2 - pc2Input := uint64(leftRotations[i])<<28 | uint64(rightRotations[i]) - // apply PC2 permutation to 7 byte input - c.subkeys[i] = permuteBlock(pc2Input, permutedChoice2[:]) - } -} |