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chacha20

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Alexander Nutz
2025-09-05 00:17:32 +02:00
parent 337f069d5d
commit d296b11940
2 changed files with 237 additions and 0 deletions
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174
chacha20.h Normal file
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/* define SLOWGRAPH_IMPL */
#ifndef SLOWCRYPT_CHACHA20_H
#define SLOWCRYPT_CHACHA20_H
#include <stdint.h>
#ifndef SLOWCRYPT_CHACHA20_FUNC
#define SLOWCRYPT_CHACHA20_FUNC /**/
#endif
typedef struct {
uint32_t state[16];
} slowcrypt_chacha20;
/*
* initialize state, run 20 iterations, serialize, xor data inplace
*
* does NOT zeroize states! zeroize manually when done.
*/
SLOWCRYPT_CHACHA20_FUNC void
slowcrypt_chacha20_block(slowcrypt_chacha20 state[2], char const key[32],
uint32_t block_ctr, char const nonce[12],
char data[64]);
/* call this to zero out memory */
SLOWCRYPT_CHACHA20_FUNC void
slowcrypt_chacha20_deinit(slowcrypt_chacha20 *state);
SLOWCRYPT_CHACHA20_FUNC void slowcrypt_chacha20_init(slowcrypt_chacha20 *state,
char const key[32],
uint32_t block_ctr,
char const nonce[12]);
SLOWCRYPT_CHACHA20_FUNC void
slowcrypt_chacha20_serialize(char buf[64], slowcrypt_chacha20 const *state);
SLOWCRYPT_CHACHA20_FUNC void
slowcrypt_chacha20_serialize_xor(char buf[64], slowcrypt_chacha20 const *state);
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 void slowcrypt_chacha20_write_ul32(char *buf,
uint32_t val);
#define SLOWCRYPT_CHACHA20_LAST32(n, bits) (((uint32_t)(n)) >> (32 - (bits)))
#define SLOWCRYPT_CHACHA20_ROL32(n, by) \
((((uint32_t)(n)) << (by)) | SLOWCRYPT_CHACHA20_LAST32((n), (by)))
#define SLOWCRYPT_CHACHA20_QROUND(state, a, b, c, d) \
do { \
state[a] += state[b]; \
state[d] ^= state[a]; \
state[d] = SLOWCRYPT_CHACHA20_ROL32(state[d], 16); \
\
state[c] += state[d]; \
state[b] ^= state[c]; \
state[b] = SLOWCRYPT_CHACHA20_ROL32(state[b], 12); \
\
state[a] += state[b]; \
state[d] ^= state[a]; \
state[d] = SLOWCRYPT_CHACHA20_ROL32(state[d], 8); \
\
state[c] += state[d]; \
state[b] ^= state[c]; \
state[b] = SLOWCRYPT_CHACHA20_ROL32(state[b], 7); \
} while (0)
#ifdef SLOWCRYPT_CHACHA20_IMPL
SLOWCRYPT_CHACHA20_FUNC void
slowcrypt_chacha20_deinit(slowcrypt_chacha20 *state) {
int i;
for (i = 0; i < 16; i++)
*(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;
return o;
}
SLOWCRYPT_CHACHA20_FUNC void slowcrypt_chacha20_write_ul32(char *buf,
uint32_t 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);
((uint8_t *)buf)[3] = (uint8_t)((val >> 24) & 0xFF);
}
SLOWCRYPT_CHACHA20_FUNC void slowcrypt_chacha20_init(slowcrypt_chacha20 *state,
char const key[32],
uint32_t block_ctr,
char const nonce[12]) {
int i;
state->state[0] = 0x61707865;
state->state[1] = 0x3320646e;
state->state[2] = 0x79622d32;
state->state[3] = 0x6b206574;
for (i = 0; i < 8; i++)
state->state[4 + i] = slowcrypt_chacha20_read_ul32(&key[i * 4]);
state->state[12] = block_ctr;
for (i = 0; i < 3; i++)
state->state[13 + i] = slowcrypt_chacha20_read_ul32(&nonce[i * 4]);
}
SLOWCRYPT_CHACHA20_FUNC void
slowcrypt_chacha20_serialize(char buf[64], slowcrypt_chacha20 const *state) {
int i;
for (i = 0; i < 16; i++)
slowcrypt_chacha20_write_ul32(&buf[i * 4], state->state[i]);
}
SLOWCRYPT_CHACHA20_FUNC void
slowcrypt_chacha20_serialize_xor(char buf[64],
slowcrypt_chacha20 const *state) {
char swp[4];
int i, j;
for (i = 0; i < 16; i++) {
slowcrypt_chacha20_write_ul32(swp, state->state[i]);
for (j = 0; j < 4; j++)
buf[i * 4 + j] ^= swp[j];
}
}
SLOWCRYPT_CHACHA20_FUNC void slowcrypt_chacha20_run(slowcrypt_chacha20 *state,
slowcrypt_chacha20 *swap,
int num_rounds) {
int i;
for (i = 0; i < 16; i++)
swap->state[i] = state->state[i];
for (i = 0; i < num_rounds; i++) {
if (i % 2 == 0) {
/* column round */
SLOWCRYPT_CHACHA20_QROUND(state->state, 0, 4, 8, 12);
SLOWCRYPT_CHACHA20_QROUND(state->state, 1, 5, 9, 13);
SLOWCRYPT_CHACHA20_QROUND(state->state, 2, 6, 10, 14);
SLOWCRYPT_CHACHA20_QROUND(state->state, 3, 7, 11, 15);
} else {
/* diagonal round */
SLOWCRYPT_CHACHA20_QROUND(state->state, 0, 5, 10, 15);
SLOWCRYPT_CHACHA20_QROUND(state->state, 1, 6, 11, 12);
SLOWCRYPT_CHACHA20_QROUND(state->state, 2, 7, 8, 13);
SLOWCRYPT_CHACHA20_QROUND(state->state, 3, 4, 9, 14);
}
}
for (i = 0; i < 16; i++)
state->state[i] += swap->state[i];
}
SLOWCRYPT_CHACHA20_FUNC void
slowcrypt_chacha20_block(slowcrypt_chacha20 state[2], char const key[32],
uint32_t block_ctr, char const nonce[12],
char data[64]) {
slowcrypt_chacha20_init(state, key, block_ctr, nonce);
slowcrypt_chacha20_run(state, &state[1], 20);
slowcrypt_chacha20_serialize_xor(data, state);
}
#endif
#endif

63
chacha20/nostd0.c Normal file
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#define SLOWCRYPT_CHACHA20_IMPL
#include "../chacha20.h"
static char key[] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a,
0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15,
0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
};
static char nonce[] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x4a, 0x00, 0x00, 0x00, 0x00,
};
static char text[] =
"Ladies and Gentlemen of the class of '99: If I could offer you only one "
"tip for the future, sunscreen would be it.";
static char expected[] = {
0x6E, 0x2E, 0x35, 0x9A, 0x25, 0x68, 0xF9, 0x80, 0x41, 0xBA, 0x07, 0x28,
0xDD, 0x0D, 0x69, 0x81, 0xE9, 0x7E, 0x7A, 0xEC, 0x1D, 0x43, 0x60, 0xC2,
0x0A, 0x27, 0xAF, 0xCC, 0xFD, 0x9F, 0xAE, 0x0B, 0xF9, 0x1B, 0x65, 0xC5,
0x52, 0x47, 0x33, 0xAB, 0x8F, 0x59, 0x3D, 0xAB, 0xCD, 0x62, 0xB3, 0x57,
0x16, 0x39, 0xD6, 0x24, 0xE6, 0x51, 0x52, 0xAB, 0x8F, 0x53, 0x0C, 0x35,
0x9F, 0x08, 0x61, 0xD8, 0x07, 0xCA, 0x0D, 0xBF, 0x50, 0x0D, 0x6A, 0x61,
0x56, 0xA3, 0x8E, 0x08, 0x8A, 0x22, 0xB6, 0x5E, 0x52, 0xBC, 0x51, 0x4D,
0x16, 0xCC, 0xF8, 0x06, 0x81, 0x8C, 0xE9, 0x1A, 0xB7, 0x79, 0x37, 0x36,
0x5A, 0xF9, 0x0B, 0xBF, 0x74, 0xA3, 0x5B, 0xE6, 0xB4, 0x0B, 0x8E, 0xED,
0xF2, 0x78, 0x5E, 0x42, 0x87, 0x4D,
};
int main(int argc, char **argv) {
slowcrypt_chacha20 state[2];
char buf[64];
int i, j, blksz;
uint32_t ctr = 1;
(void)argc;
(void)argv;
for (i = 0; i < (int)(sizeof(text) - 1); i += 64) {
blksz = (sizeof(text) - 1) - i;
if (blksz > 64)
blksz = 64;
for (j = 0; j < blksz; j++) {
buf[j] = text[i + j];
}
slowcrypt_chacha20_block(state, key, ctr, nonce, buf);
ctr++;
for (j = 0; j < blksz; j++)
if (buf[j] != expected[i + j])
return 1;
}
slowcrypt_chacha20_deinit(&state[0]);
slowcrypt_chacha20_deinit(&state[1]);
for (i = 0; i < 64; i++)
buf[i] = 0;
return 0;
}