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randombytes_salsa20 example: rekey after 16 blocks or after calling _buf()

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This commit is contained in:
Frank Denis 2014-07-31 21:58:14 -07:00
parent e907196101
commit 9ac321368a
1 changed files with 22 additions and 6 deletions
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28
src/libsodium/randombytes/salsa20/randombytes_salsa20_random.c
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@ -18,6 +18,7 @@
#include "crypto_core_salsa20.h"
#include "crypto_auth_hmacsha512256.h"
#include "crypto_generichash.h"
#include "crypto_stream_salsa20.h"
#include "randombytes.h"
#include "randombytes_salsa20_random.h"
@ -41,7 +42,7 @@ BOOLEAN NTAPI RtlGenRandom(PVOID RandomBuffer, ULONG RandomBufferLength);
typedef struct Salsa20Random_ {
unsigned char key[crypto_stream_salsa20_KEYBYTES];
unsigned char rnd32[SALSA20_RANDOM_BLOCK_SIZE];
unsigned char rnd32[16U * SALSA20_RANDOM_BLOCK_SIZE];
uint64_t nonce;
size_t rnd32_outleft;
#ifndef _MSC_VER
@ -214,14 +215,26 @@ randombytes_salsa20_random_stir_if_needed(void)
#endif
}
static void
randombytes_salsa20_random_rekey(const unsigned char * const mix)
{
unsigned char *key = stream.key;
size_t i;
for (i = (size_t) 0U; i < sizeof stream.key; i++) {
key[i] ^= mix[i];
}
}
static uint32_t
randombytes_salsa20_random_getword(void)
{
uint32_t val;
int ret;
COMPILER_ASSERT(sizeof stream.rnd32 >= sizeof val);
COMPILER_ASSERT(sizeof stream.rnd32 % sizeof val == (size_t) 0U);
COMPILER_ASSERT(sizeof stream.rnd32 >= (sizeof stream.key) + (sizeof val));
COMPILER_ASSERT(((sizeof stream.rnd32) - (sizeof stream.key))
% sizeof val == (size_t) 0U);
if (stream.rnd32_outleft <= (size_t) 0U) {
randombytes_salsa20_random_stir_if_needed();
COMPILER_ASSERT(sizeof stream.nonce == crypto_stream_salsa20_NONCEBYTES);
@ -230,11 +243,13 @@ randombytes_salsa20_random_getword(void)
(unsigned char *) &stream.nonce,
stream.key);
assert(ret == 0);
stream.rnd32_outleft = (sizeof stream.rnd32) - (sizeof stream.key);
randombytes_salsa20_random_rekey(&stream.rnd32[stream.rnd32_outleft]);
stream.nonce++;
stream.rnd32_outleft = sizeof stream.rnd32;
}
stream.rnd32_outleft -= sizeof val;
memcpy(&val, &stream.rnd32[stream.rnd32_outleft], sizeof val);
memset(&stream.rnd32[stream.rnd32_outleft], 0, sizeof val);
return val;
}
@ -278,10 +293,11 @@ randombytes_salsa20_random_buf(void * const buf, const size_t size)
assert(size <= ULONG_LONG_MAX);
#endif
ret = crypto_stream_salsa20((unsigned char *) buf, (unsigned long long) size,
(unsigned char *) &stream.nonce,
stream.key);
(unsigned char *) &stream.nonce, stream.key);
assert(ret == 0);
stream.nonce++;
crypto_stream_salsa20_xor(stream.key, stream.key, sizeof stream.key,
(unsigned char *) &stream.nonce, stream.key);
}
/*