mirror of
https://github.com/vlang/v.git
synced 2023-08-10 21:13:21 +03:00
190 lines
5.5 KiB
V
190 lines
5.5 KiB
V
// The source code refers to the go standard library, which can be merged with AES later
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module des
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import encoding.binary
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fn feistel(ll u32, rr u32, k0 u64, k1 u64) (u32, u32) {
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mut l := ll
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mut r := rr
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mut t := r ^ u32(k0 >> 32)
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l ^= feistel_box[7][t & 0x3f] ^ feistel_box[5][(t >> 8) & 0x3f] ^ feistel_box[3][(t >> 16) & 0x3f] ^ feistel_box[1][(t >> 24) & 0x3f]
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t = ((r << 28) | (r >> 4)) ^ u32(k0)
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l ^= feistel_box[6][t & 0x3f] ^ feistel_box[4][(t >> 8) & 0x3f] ^ feistel_box[2][(t >> 16) & 0x3f] ^ feistel_box[0][(t >> 24) & 0x3f]
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t = l ^ u32(k1 >> 32)
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r ^= feistel_box[7][t & 0x3f] ^ feistel_box[5][(t >> 8) & 0x3f] ^ feistel_box[3][(t >> 16) & 0x3f] ^ feistel_box[1][(t >> 24) & 0x3f]
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t = ((l << 28) | (l >> 4)) ^ u32(k1)
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r ^= feistel_box[6][t & 0x3f] ^ feistel_box[4][(t >> 8) & 0x3f] ^ feistel_box[2][(t >> 16) & 0x3f] ^ feistel_box[0][(t >> 24) & 0x3f]
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return l, r
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}
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fn crypt_block(subkeys []u64, mut dst []byte, src []byte, decrypt bool) {
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mut b := binary.big_endian_u64(src)
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b = permute_initial_block(b)
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mut left, mut right := u32(b >> 32), u32(b)
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left = (left << 1) | (left >> 31)
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right = (right << 1) | (right >> 31)
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if decrypt {
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for i := 0; i < 8; i++ {
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left, right = feistel(left, right, subkeys[15 - 2 * i], subkeys[15 - (2 * i + 1)])
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}
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} else {
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for i := 0; i < 8; i++ {
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left, right = feistel(left, right, subkeys[2 * i], subkeys[2 * i + 1])
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}
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}
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left = (left << 31) | (left >> 1)
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right = (right << 31) | (right >> 1)
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// switch left & right and perform final permutation
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pre_output := (u64(right) << 32) | u64(left)
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binary.big_endian_put_u64(mut dst, permute_final_block(pre_output))
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}
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// Encrypt one block from src into dst, using the subkeys.
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pub fn encrypt_block(subkeys []u64, mut dst []byte, src []byte) {
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crypt_block(subkeys, mut dst, src, false)
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}
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// Decrypt one block from src into dst, using the subkeys.
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fn decrypt_block(subkeys []u64, mut dst []byte, src []byte) {
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crypt_block(subkeys, mut dst, src, true)
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}
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// general purpose function to perform DES block permutations
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fn permute_block(src u64, permutation []byte) u64 {
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mut block := u64(0)
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for position, n in permutation {
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bit := (src >> u64(u8(n))) & 1
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block |= bit << u64((permutation.len - 1) - position)
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}
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return block
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}
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// permuteInitial_block is equivalent to the permutation defined
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// by initialPermutation.
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fn permute_initial_block(b u64) u64 {
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// block = b7 b6 b5 b4 b3 b2 b1 b0 (8 bytes)
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mut block := b
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mut b1 := block >> 48
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mut b2 := block << 48
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block ^= b1 ^ b2 ^ b1 << 48 ^ b2 >> 48
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// block = b1 b0 b5 b4 b3 b2 b7 b6
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b1 = block >> 32 & 0xff00ff
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b2 = (block & 0xff00ff00)
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block ^= b1 << 32 ^ b2 ^ b1 << 8 ^ b2 << 24 // exchange b0 b4 with b3 b7
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// block is now b1 b3 b5 b7 b0 b2 b4 b6, the permutation:
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// ... 8
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// ... 24
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// ... 40
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// ... 56
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// 7 6 5 4 3 2 1 0
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// 23 22 21 20 19 18 17 16
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// ... 32
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// ... 48
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// exchange 4,5,6,7 with 32,33,34,35 etc.
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b1 = block & 0x0f0f00000f0f0000
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b2 = block & 0x0000f0f00000f0f0
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block ^= b1 ^ b2 ^ b1 >> 12 ^ b2 << 12
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// block is the permutation:
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//
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// [+8] [+40]
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//
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// 7 6 5 4
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// 23 22 21 20
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// 3 2 1 0
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// 19 18 17 16 [+32]
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// exchange 0,1,4,5 with 18,19,22,23
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b1 = block & 0x3300330033003300
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b2 = block & 0x00cc00cc00cc00cc
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block ^= b1 ^ b2 ^ b1 >> 6 ^ b2 << 6
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// block is the permutation:
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// 15 14
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// 13 12
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// 11 10
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// 9 8
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// 7 6
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// 5 4
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// 3 2
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// 1 0 [+16] [+32] [+64]
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// exchange 0,2,4,6 with 9,11,13,15:
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b1 = block & 0xaaaaaaaa55555555
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block ^= b1 ^ b1 >> 33 ^ b1 << 33
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// block is the permutation:
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// 6 14 22 30 38 46 54 62
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// 4 12 20 28 36 44 52 60
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// 2 10 18 26 34 42 50 58
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// 0 8 16 24 32 40 48 56
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// 7 15 23 31 39 47 55 63
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// 5 13 21 29 37 45 53 61
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// 3 11 19 27 35 43 51 59
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// 1 9 17 25 33 41 49 57
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return block
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}
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// permuteInitial_block is equivalent to the permutation defined
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// by finalPermutation.
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fn permute_final_block(b u64) u64 {
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// Perform the same bit exchanges as permuteInitial_block
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// but in reverse order.
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mut block := b
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mut b1 := block & 0xaaaaaaaa55555555
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block ^= b1 ^ b1 >> 33 ^ b1 << 33
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b1 = block & 0x3300330033003300
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mut b2 := block & 0x00cc00cc00cc00cc
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block ^= b1 ^ b2 ^ b1 >> 6 ^ b2 << 6
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b1 = block & 0x0f0f00000f0f0000
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b2 = block & 0x0000f0f00000f0f0
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block ^= b1 ^ b2 ^ b1 >> 12 ^ b2 << 12
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b1 = block >> 32 & 0xff00ff
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b2 = (block & 0xff00ff00)
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block ^= b1 << 32 ^ b2 ^ b1 << 8 ^ b2 << 24
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b1 = block >> 48
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b2 = block << 48
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block ^= b1 ^ b2 ^ b1 << 48 ^ b2 >> 48
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return block
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}
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// creates 16 28-bit blocks rotated according
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// to the rotation schedule
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fn ks_rotate(ain u32) []u32 {
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mut out := []u32{len: 16}
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mut last := ain
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for i := 0; i < 16; i++ {
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// 28-bit circular left shift
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left := (last << (4 + ks_rotations[i])) >> 4
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right := (last << 4) >> (32 - ks_rotations[i])
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out[i] = left | right
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last = out[i]
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}
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return out
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}
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// Expand 48-bit input to 64-bit, with each 6-bit block padded by extra two bits at the top.
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// By doing so, we can have the input blocks (four bits each), and the key blocks (six bits each) well-aligned without
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// extra shifts/rotations for alignments.
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fn unpack(x u64) u64 {
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return ((x >> (6 * 1)) & 0xff) << (8 * 0) | ((x >> (6 * 3)) & 0xff) << (8 * 1) | ((x >> (6 * 5)) & 0xff) << (8 * 2) | ((x >> (6 * 7)) & 0xff) << (8 * 3) | ((x >> (6 * 0)) & 0xff) << (8 * 4) | ((x >> (6 * 2)) & 0xff) << (8 * 5) | ((x >> (6 * 4)) & 0xff) << (8 * 6) | ((x >> (6 * 6)) & 0xff) << (8 * 7)
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}
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