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This commit is contained in:
Alexander Nutz
2025-09-05 11:59:29 +02:00
parent 6203420266
commit 24bc8bee8f
3 changed files with 127 additions and 39 deletions
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116
chacha20.h
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@@ -1,16 +1,100 @@
/* define SLOWGRAPH_IMPL */
/*
* Copyright (c) 2025 Alexander Nutz
* MIT licensed, see below documentation
*
*
* ======== ChaCha20 stream chiper ========
*
* Security considerations:
* - manually zeroize memory (depending on your application)
* - length extension attack:
* ChaCha20 is only a stream chiper, and, like AES,
* does NOT prevent against length extension attacks.
* Consider using ChaCha20-Poly1305 instead.
*
*
* Configuration options:
* - SLOWCRYPT_CHACHA20_IMPL
* - SLOWCRYPT_CHACHA20_FUNC
* will be used in front of every function definition / declaration
* - SLOWCRYPT_CHACHA20_UINT32
* if this is not set, will include <stdint.h>, and use `uint32_t`
*
*
* Compatibility:
* requires only a C89 compiler.
*
*
* Usage example 1: en-/de- crypt blocks of data
* slowcrypt_chacha20 state[2];
* uint32_t ctr = 1;
* char buf[64];
*
* iterate over blocks {
* copy block into buf (can pad with zeros)
* slowcrypt_chacha20_block(state, key, ctr, nonce, buf);
* ctr += 1;
* }
*
* # optionally zeroize memory
* slowcrypt_chacha20_deinit(&state[0]);
* slowcrypt_chacha20_deinit(&state[1]);
* bzero(buf, 64);
*
*
* Usage example 2: CSPRNG (cryptographically secure pseudo random number generator)
* slowcrypt_chacha20 state[2];
* uint32_t ctr = 1;
* char buf[64];
*
* while need random numbers {
* slowcrypt_chacha20_init(state, key, block_ctr, nonce);
* slowcrypt_chacha20_run(state, &state[1], 20);
* slowcrypt_chacha20_serialize(buf, state);
* yield buf
* ctr += 1;
* }
*
* # optionally zeroize memory
* slowcrypt_chacha20_deinit(&state[0]);
* slowcrypt_chacha20_deinit(&state[1]);
* bzero(buf, 64);
*
*/
/*
* Copyright (c) 2025 Alexander Nutz
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
* of the Software, and to permit persons to whom the Software is furnished to do
* so, subject to the following conditions:
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#ifndef SLOWCRYPT_CHACHA20_H
#define SLOWCRYPT_CHACHA20_H
#ifndef SLOWCRYPT_CHACHA20_UINT32
#include <stdint.h>
#define SLOWCRYPT_CHACHA20_UINT32 uint32_t
#endif
#ifndef SLOWCRYPT_CHACHA20_FUNC
#define SLOWCRYPT_CHACHA20_FUNC /**/
#endif
typedef struct {
uint32_t state[16];
SLOWCRYPT_CHACHA20_UINT32 state[16];
} slowcrypt_chacha20;
/*
@@ -20,7 +104,7 @@ typedef struct {
*/
SLOWCRYPT_CHACHA20_FUNC void
slowcrypt_chacha20_block(slowcrypt_chacha20 state[2], char const key[32],
uint32_t block_ctr, char const nonce[12],
SLOWCRYPT_CHACHA20_UINT32 block_ctr, char const nonce[12],
char data[64]);
/* call this to zero out memory */
@@ -29,7 +113,7 @@ slowcrypt_chacha20_deinit(slowcrypt_chacha20 *state);
SLOWCRYPT_CHACHA20_FUNC void slowcrypt_chacha20_init(slowcrypt_chacha20 *state,
char const key[32],
uint32_t block_ctr,
SLOWCRYPT_CHACHA20_UINT32 block_ctr,
char const nonce[12]);
SLOWCRYPT_CHACHA20_FUNC void
@@ -42,15 +126,15 @@ SLOWCRYPT_CHACHA20_FUNC void slowcrypt_chacha20_run(slowcrypt_chacha20 *state,
slowcrypt_chacha20 *swap,
int num_rounds);
SLOWCRYPT_CHACHA20_FUNC uint32_t slowcrypt_chacha20_read_ul32(char const *buf);
SLOWCRYPT_CHACHA20_FUNC SLOWCRYPT_CHACHA20_UINT32 slowcrypt_chacha20_read_ul32(char const *buf);
SLOWCRYPT_CHACHA20_FUNC void slowcrypt_chacha20_write_ul32(char *buf,
uint32_t val);
SLOWCRYPT_CHACHA20_UINT32 val);
#define SLOWCRYPT_CHACHA20_LAST32(n, bits) (((uint32_t)(n)) >> (32 - (bits)))
#define SLOWCRYPT_CHACHA20_LAST32(n, bits) (((SLOWCRYPT_CHACHA20_UINT32)(n)) >> (32 - (bits)))
#define SLOWCRYPT_CHACHA20_ROL32(n, by) \
((((uint32_t)(n)) << (by)) | SLOWCRYPT_CHACHA20_LAST32((n), (by)))
((((SLOWCRYPT_CHACHA20_UINT32)(n)) << (by)) | SLOWCRYPT_CHACHA20_LAST32((n), (by)))
#define SLOWCRYPT_CHACHA20_QROUND(state, a, b, c, d) \
do { \
@@ -80,16 +164,16 @@ slowcrypt_chacha20_deinit(slowcrypt_chacha20 *state) {
*(volatile int *)&state->state[i] = 0;
}
SLOWCRYPT_CHACHA20_FUNC uint32_t slowcrypt_chacha20_read_ul32(char const *buf) {
uint32_t o = (uint32_t)((uint8_t const *)buf)[0];
o |= (uint32_t)((uint8_t const *)buf)[1] << 8;
o |= (uint32_t)((uint8_t const *)buf)[2] << 16;
o |= (uint32_t)((uint8_t const *)buf)[3] << 24;
SLOWCRYPT_CHACHA20_FUNC SLOWCRYPT_CHACHA20_UINT32 slowcrypt_chacha20_read_ul32(char const *buf) {
SLOWCRYPT_CHACHA20_UINT32 o = (SLOWCRYPT_CHACHA20_UINT32)((uint8_t const *)buf)[0];
o |= (SLOWCRYPT_CHACHA20_UINT32)((uint8_t const *)buf)[1] << 8;
o |= (SLOWCRYPT_CHACHA20_UINT32)((uint8_t const *)buf)[2] << 16;
o |= (SLOWCRYPT_CHACHA20_UINT32)((uint8_t const *)buf)[3] << 24;
return o;
}
SLOWCRYPT_CHACHA20_FUNC void slowcrypt_chacha20_write_ul32(char *buf,
uint32_t val) {
SLOWCRYPT_CHACHA20_UINT32 val) {
((uint8_t *)buf)[0] = (uint8_t)(val & 0xFF);
((uint8_t *)buf)[1] = (uint8_t)((val >> 8) & 0xFF);
((uint8_t *)buf)[2] = (uint8_t)((val >> 16) & 0xFF);
@@ -98,7 +182,7 @@ SLOWCRYPT_CHACHA20_FUNC void slowcrypt_chacha20_write_ul32(char *buf,
SLOWCRYPT_CHACHA20_FUNC void slowcrypt_chacha20_init(slowcrypt_chacha20 *state,
char const key[32],
uint32_t block_ctr,
SLOWCRYPT_CHACHA20_UINT32 block_ctr,
char const nonce[12]) {
int i;
state->state[0] = 0x61707865;
@@ -162,7 +246,7 @@ SLOWCRYPT_CHACHA20_FUNC void slowcrypt_chacha20_run(slowcrypt_chacha20 *state,
SLOWCRYPT_CHACHA20_FUNC void
slowcrypt_chacha20_block(slowcrypt_chacha20 state[2], char const key[32],
uint32_t block_ctr, char const nonce[12],
SLOWCRYPT_CHACHA20_UINT32 block_ctr, char const nonce[12],
char data[64]) {
slowcrypt_chacha20_init(state, key, block_ctr, nonce);
slowcrypt_chacha20_run(state, &state[1], 20);