v/vlib/crypto/des/des.v

170 lines
4.7 KiB
V
Raw Normal View History

// The source code refers to the go standard library
module des
import crypto.cipher
import crypto.internal.subtle
import encoding.binary
const block_size = 8
// A tripleDesCipher is an instance of TripleDES encryption.
struct TripleDesCipher {
block_size int = des.block_size
mut:
cipher1 DesCipher
cipher2 DesCipher
cipher3 DesCipher
}
// DesCipher is an instance of DES encryption.
struct DesCipher {
block_size int = des.block_size
mut:
subkeys [16]u64
}
// NewCipher creates and returns a new cipher.Block.
pub fn new_cipher(key []byte) cipher.Block {
if key.len != 8 {
panic('crypto.aes: invalid key size')
}
mut c := DesCipher{}
c.generate_subkeys(key)
return c
}
// creates 16 56-bit subkeys from the original key
fn (mut c DesCipher) generate_subkeys(key_bytes []byte) {
// feistel_box_once.do(initFeistel_box)
// apply PC1 permutation to key
key := binary.big_endian_u64(key_bytes)
permuted_key := permute_block(key, permuted_choice1[..])
// rotate halves of permuted key according to the rotation schedule
left_rotations := ks_rotate(u32(permuted_key >> 28))
right_rotations := ks_rotate(u32(permuted_key << 4) >> 4)
// generate subkeys
for i := 0; i < 16; i++ {
// combine halves to form 56-bit input to PC2
pc2_input := u64(left_rotations[i]) << 28 | u64(right_rotations[i])
// apply PC2 permutation to 7 byte input
c.subkeys[i] = unpack(permute_block(pc2_input, permuted_choice2[..]))
}
}
pub fn (c &DesCipher) encrypt(mut dst []byte, src []byte) {
if src.len < des.block_size {
panic('crypto/des: input not full block')
}
if dst.len < des.block_size {
panic('crypto/des: output not full block')
}
if subtle.inexact_overlap(dst[..des.block_size], src[..des.block_size]) {
panic('crypto/des: invalid buffer overlap')
}
encrypt_block(c.subkeys[..], mut dst, src)
}
pub fn (c &DesCipher) decrypt(mut dst []byte, src []byte) {
if src.len < des.block_size {
panic('crypto/des: input not full block')
}
if dst.len < des.block_size {
panic('crypto/des: output not full block')
}
if subtle.inexact_overlap(dst[..des.block_size], src[..des.block_size]) {
panic('crypto/des: invalid buffer overlap')
}
decrypt_block(c.subkeys[..], mut dst, src)
}
// NewTripleDesCipher creates and returns a new cipher.Block.
pub fn new_triple_des_cipher(key []byte) cipher.Block {
if key.len != 24 {
panic('crypto.des: invalid key size')
}
mut c := TripleDesCipher{}
c.cipher1.generate_subkeys(key[..8])
c.cipher2.generate_subkeys(key[8..16])
c.cipher3.generate_subkeys(key[16..])
return c
}
pub fn (c &TripleDesCipher) encrypt(mut dst []byte, src []byte) {
if src.len < des.block_size {
panic('crypto/des: input not full block')
}
if dst.len < des.block_size {
panic('crypto/des: output not full block')
}
if subtle.inexact_overlap(dst[..des.block_size], src[..des.block_size]) {
panic('crypto/des: invalid buffer overlap')
}
mut b := binary.big_endian_u64(src)
b = permute_initial_block(b)
mut left, mut right := u32(b >> 32), u32(b)
left = (left << 1) | (left >> 31)
right = (right << 1) | (right >> 31)
for i := 0; i < 8; i++ {
left, right = feistel(left, right, c.cipher1.subkeys[2 * i], c.cipher1.subkeys[2 * i + 1])
}
for i := 0; i < 8; i++ {
right, left = feistel(right, left, c.cipher2.subkeys[15 - 2 * i], c.cipher2.subkeys[15 - (
2 * i + 1)])
}
for i := 0; i < 8; i++ {
left, right = feistel(left, right, c.cipher3.subkeys[2 * i], c.cipher3.subkeys[2 * i + 1])
}
left = (left << 31) | (left >> 1)
right = (right << 31) | (right >> 1)
pre_output := (u64(right) << 32) | u64(left)
binary.big_endian_put_u64(mut dst, permute_final_block(pre_output))
}
pub fn (c &TripleDesCipher) decrypt(mut dst []byte, src []byte) {
if src.len < des.block_size {
panic('crypto/des: input not full block')
}
if dst.len < des.block_size {
panic('crypto/des: output not full block')
}
if subtle.inexact_overlap(dst[..des.block_size], src[..des.block_size]) {
panic('crypto/des: invalid buffer overlap')
}
mut b := binary.big_endian_u64(src)
b = permute_initial_block(b)
mut left, mut right := u32(b >> 32), u32(b)
left = (left << 1) | (left >> 31)
right = (right << 1) | (right >> 31)
for i := 0; i < 8; i++ {
left, right = feistel(left, right, c.cipher3.subkeys[15 - 2 * i], c.cipher3.subkeys[15 - (
2 * i + 1)])
}
for i := 0; i < 8; i++ {
right, left = feistel(right, left, c.cipher2.subkeys[2 * i], c.cipher2.subkeys[2 * i + 1])
}
for i := 0; i < 8; i++ {
left, right = feistel(left, right, c.cipher1.subkeys[15 - 2 * i], c.cipher1.subkeys[15 - (
2 * i + 1)])
}
left = (left << 31) | (left >> 1)
right = (right << 31) | (right >> 1)
pre_output := (u64(right) << 32) | u64(left)
binary.big_endian_put_u64(mut dst, permute_final_block(pre_output))
}