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#include <stdlib.h>
#include <assert.h>
#include <stddef.h>
#include <errno.h>
#include <string.h>
#include "foundation_prim.h"
#include "foundation_system.h"
#include "foundation_bits.h"
#if defined(FOUNDATION_SYSTEM_LINUX)
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#endif
#include <stdio.h>
#if defined(FOUNDATION_SYSTEM_LINUX) && defined(SYS_getrandom)
int foundation_sysrandom_linux(void *buf, size_t length)
{
unsigned int flags = 1; /* RANDOM=0x2, NONBLOCK=0x1 */
size_t i = 0;
/* special case to detect availability */
if (length == 0) {
int r = syscall(SYS_getrandom, buf, 0, flags);
return (r == -1) ? -1 : 0;
}
while (i < length) {
int r = syscall(SYS_getrandom, buf + i, length - i, flags);
if (r <= 0) {
if (errno != -EAGAIN)
return -errno;
}
if (r > 0)
i += r;
}
return 0;
}
#else
int foundation_sysrandom_linux(void *buf, size_t length) { return -ENODEV; }
#endif
#define CHACHA_KEY_SIZE 32
#define CHACHA_NONCE_SIZE 16
#define CHACHA_OUTPUT_SIZE 64
#define CHACHA_KEY_SIZE32 8
#define CHACHA_NONCE_SIZE32 4
#define CHACHA_OUTPUT_SIZE32 16
#define QR(a,b,c,d) \
a += b; d = rol32(d ^ a,16); \
c += d; b = rol32(b ^ c,12); \
a += b; d = rol32(d ^ a, 8); \
c += d; b = rol32(b ^ c, 7);
static void chacha_core(int rounds,
uint8_t out8[CHACHA_OUTPUT_SIZE],
const uint8_t key8[CHACHA_KEY_SIZE],
const uint8_t nonce8[CHACHA_NONCE_SIZE])
{
uint32_t x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
int i;
static const uint8_t sigma8[16] = "expand 32-byte k";
uint32_t *out = (uint32_t *) out8;
uint32_t *key = (uint32_t *) key8;
uint32_t *nonce = (uint32_t *) nonce8;
uint32_t *sigma = (uint32_t *) sigma8;
x0 = sigma[0]; x1 = sigma[1]; x2 = sigma[2]; x3 = sigma[3];
x4 = key[0] ; x5 = key[1] ; x6 = key[2] ; x7 = key[3] ;
x8 = key[4] ; x9 = key[5] ; x10 = key[6] ; x11 = key[7] ;
x12 = nonce[0]; x13 = nonce[1]; x14 = nonce[2]; x15 = nonce[3];
for (i = rounds; i > 0; i -= 2) {
QR(x0, x4, x8, x12);
QR(x1, x5, x9, x13);
QR(x2, x6, x10, x14);
QR(x3, x7, x11, x15);
QR(x0, x5, x10, x15);
QR(x1, x6, x11, x12);
QR(x2, x7, x8, x13);
QR(x3, x4, x9, x14);
}
x0 += sigma[0]; x1 += sigma[1]; x2 += sigma[2]; x3 += sigma[3];
x4 += key[0] ; x5 += key[1] ; x6 += key[2] ; x7 += key[3] ;
x8 += key[4] ; x9 += key[5] ; x10 += key[6] ; x11 += key[7] ;
x12 += nonce[0]; x13 += nonce[1]; x14 += nonce[2]; x15 += nonce[3];
out[0] = cpu_to_le32(x0);
out[1] = cpu_to_le32(x1);
out[2] = cpu_to_le32(x2);
out[3] = cpu_to_le32(x3);
out[4] = cpu_to_le32(x4);
out[5] = cpu_to_le32(x5);
out[6] = cpu_to_le32(x6);
out[7] = cpu_to_le32(x7);
out[8] = cpu_to_le32(x8);
out[9] = cpu_to_le32(x9);
out[10] = cpu_to_le32(x10);
out[11] = cpu_to_le32(x11);
out[12] = cpu_to_le32(x12);
out[13] = cpu_to_le32(x13);
out[14] = cpu_to_le32(x14);
out[15] = cpu_to_le32(x15);
}
int foundation_rngV1_generate(uint8_t newkey[CHACHA_KEY_SIZE], uint8_t *dst, uint8_t key[CHACHA_KEY_SIZE], FsCountOf bytes)
{
const int rounds = 20;
uint8_t nonce[CHACHA_NONCE_SIZE] = { 0 };
uint8_t buf[CHACHA_OUTPUT_SIZE]; /* for partial buffer */
if (!bytes)
return 0;
for (; bytes >= CHACHA_OUTPUT_SIZE; bytes -= CHACHA_OUTPUT_SIZE, dst += CHACHA_OUTPUT_SIZE) {
chacha_core(rounds, dst, key, nonce);
if (++nonce[0] == 0)
nonce[1]++;
}
assert(bytes < CHACHA_OUTPUT_SIZE);
chacha_core(rounds, buf, key, nonce);
int remaining = CHACHA_OUTPUT_SIZE - bytes;
if (remaining >= CHACHA_KEY_SIZE) {
memcpy(dst, buf, bytes);
memcpy(newkey, buf + bytes, CHACHA_KEY_SIZE);
} else {
memcpy(dst, buf, bytes);
if (++nonce[0] == 0)
nonce[1]++;
chacha_core(rounds, buf, key, nonce);
memcpy(newkey, buf, CHACHA_KEY_SIZE);
}
memset(buf, 0, CHACHA_OUTPUT_SIZE);
return 0;
}
int foundation_rngV1_generate_word32(uint8_t newkey[CHACHA_KEY_SIZE], uint32_t *dst_w, uint8_t key[CHACHA_KEY_SIZE])
{
return foundation_rngV1_generate(newkey, (uint8_t*)dst_w, key, sizeof(uint32_t));
}
int foundation_rngV1_generate_word64(uint8_t newkey[CHACHA_KEY_SIZE], uint64_t *dst_w, uint8_t key[CHACHA_KEY_SIZE])
{
return foundation_rngV1_generate(newkey, (uint8_t*)dst_w, key, sizeof(uint64_t));
}
int foundation_rngV1_generate_f32(uint8_t newkey[CHACHA_KEY_SIZE], float *dst_w, uint8_t key[CHACHA_KEY_SIZE])
{
uint32_t const UPPER_MASK = 0x3F800000UL;
uint32_t const LOWER_MASK = 0x007FFFFFUL;
uint32_t tmp32;
int r = foundation_rngV1_generate_word32(newkey, &tmp32, key);
tmp32 = UPPER_MASK | (tmp32 & LOWER_MASK);
*dst_w = (float)tmp32 - 1.0;
return r;
}
int foundation_rngV1_generate_f64(uint8_t newkey[CHACHA_KEY_SIZE], double *dst_w, uint8_t key[CHACHA_KEY_SIZE])
{
uint64_t const UPPER_MASK = 0x3FF0000000000000ULL;
uint64_t const LOWER_MASK = 0x000FFFFFFFFFFFFFULL;
uint64_t tmp64;
int r = foundation_rngV1_generate_word64(newkey, &tmp64, key);
tmp64 = UPPER_MASK | (tmp64 & LOWER_MASK);
*dst_w = (double)tmp64 - 1.0;
return r;
}
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