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DES

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This commit is contained in:
Milan Špinka
2025-01-27 20:53:15 +01:00
parent f9333e3e7c
commit 556a7ab200
1 changed files with 22 additions and 7 deletions
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29
src/primitive/blockcipher/des.zig
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@ -45,6 +45,13 @@ pub const DES_BIT_SELECTION_TABLE_E = [_]u5{
28, 29, 30, 31, 32, 1,
};
pub const DES_PERMUTATION_FUNCTION_P = [_]u5{
16, 7, 20, 21, 29, 12, 28, 17,
1, 15, 23, 26, 5, 18, 31, 10,
2, 8, 24, 14, 32, 27, 3, 9,
19, 13, 30, 6, 22, 11, 4, 25,
};
pub const DES_KS_SHIFT_SCHEDULE = .{ 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1 };
// ----------------------------------- ENCRYPTION/DECRYPTION ----------------------------------- //
@ -88,8 +95,7 @@ pub fn des_expand_key(key: *const [DES_ENCODED_KEY_SIZE]u8) [DES_N_ROUNDS][DES_S
var subkeys: [DES_N_ROUNDS][DES_SUBKEY_SIZE]u8 = undefined;
for (0..DES_N_ROUNDS) |i| {
rol(cd[0 .. DES_TRUE_KEY_SIZE / 2], DES_KS_SHIFT_SCHEDULE[i]);
rol(cd[DES_TRUE_KEY_SIZE / 2 ..], DES_KS_SHIFT_SCHEDULE[i]);
rotate_halves_left(cd[0..], DES_KS_SHIFT_SCHEDULE[i]);
des_permuted_choice_2(cd, &subkeys[i]);
}
}
@ -123,7 +129,14 @@ pub fn des_perform_round(state: *[DES_BLOCK_SIZE]u8, subkey: *[DES_SUBKEY_SIZE]u
@memcpy(state[DES_BLOCK_SIZE / 2 ..], new_r[0..]);
}
pub fn des_cipher_function_f(word: [DES_BLOCK_SIZE / 2]u8, subkey: [DES_SUBKEY_SIZE]u8) [DES_BLOCK_SIZE / 2]u8 {
pub fn des_cipher_function_f(word: [DES_BLOCK_SIZE / 2]u8, subkey: *const [DES_SUBKEY_SIZE]u8) [DES_BLOCK_SIZE / 2]u8 {
// The input word is expanded to 48 bits.
var expanded_word: [DES_SUBKEY_SIZE]u8 = undefined;
permute_bits(DES_SUBKEY_SIZE, word, &expanded_word, &DES_BIT_SELECTION_TABLE_E);
for (0..DES_SUBKEY_SIZE) |i|
expanded_word[i] ^= subkey[i];
// todo
_ = .{ word, subkey };
}
@ -138,9 +151,11 @@ pub fn des_inv_initial_permutation(in: *const [DES_BLOCK_SIZE]u8, out: *[DES_BLO
// ----------------------------------- HELPERS ----------------------------------- //
fn permute_bits(L: comptime_int, in: *const [8]u8, out: *[L]u8, key: [8 * L]u6) void {
fn permute_bits(L: comptime_int, in: []u8, out: *[L]u8, key: [8 * L]u6) void {
for (0..8 * L) |i| {
const pi = key[i];
if (pi >= in.len * 8)
@panic("Bit index out of range!");
const bit = get_nth_bit(in, pi);
set_nth_bit(out, pi, bit);
}
@ -170,9 +185,9 @@ fn xor(L: comptime_int, a: [L]u8, b: [L]u8) [L]u8 {
return result;
}
fn rol(word: *[DES_TRUE_KEY_SIZE / 2]u8, positions: comptime_int) void {
// todo
_ = .{ word, positions };
fn rotate_halves_left(cd: *[DES_TRUE_KEY_SIZE]u8, positions: comptime_int) void {
// TODO
_ = .{ cd, positions };
}
// ----------------------------------- TEST VECTORS ----------------------------------- //