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Add hash_to_ristretto255

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Identifier should be ristretto255_XMD:SHA-512_R255MAP_RO_
This commit is contained in:
Frank Denis 2020-08-23 18:28:58 +02:00
parent ee962b33ae
commit 33b935921c
2 changed files with 81 additions and 0 deletions
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67
src/libsodium/crypto_core/ed25519/core_ristretto255.c
View File

@ -3,6 +3,7 @@
#include "crypto_core_ed25519.h"
#include "crypto_core_ristretto255.h"
#include "crypto_hash_sha512.h"
#include "private/common.h"
#include "private/ed25519_ref10.h"
#include "randombytes.h"
@ -67,6 +68,72 @@ crypto_core_ristretto255_from_hash(unsigned char *p, const unsigned char *r)
return 0;
}
#define HASH_BYTES crypto_hash_sha512_BYTES
#define HASH_BLOCKBYTES 128U
#define HASH_L crypto_core_ristretto255_HASHBYTES
static int
_string_to_element(unsigned char *p,
const char *ctx, const unsigned char *msg, size_t msg_len)
{
crypto_hash_sha512_state st;
const unsigned char empty_block[128] = { 0 };
unsigned char u0[HASH_BYTES];
unsigned char t[3] = { 0U, HASH_L, 0U};
unsigned char ctx_len_u8;
size_t ctx_len = ctx != NULL ? strlen(ctx) : 0U;
COMPILER_ASSERT(HASH_L <= 0xff);
if (ctx_len > (size_t) 0xff) {
crypto_hash_sha512_init(&st);
crypto_hash_sha512_update(&st,
(const unsigned char *) "H2C-OVERSIZE-DST-",
sizeof "H2C-OVERSIZE-DST-" - 1U);
crypto_hash_sha512_update(&st, (const unsigned char *) ctx, ctx_len);
crypto_hash_sha512_final(&st, u0);
ctx = (const char *) u0;
ctx_len = HASH_BYTES;
COMPILER_ASSERT(HASH_BYTES <= (size_t) 0xff);
}
ctx_len_u8 = (unsigned char) ctx_len;
crypto_hash_sha512_init(&st);
crypto_hash_sha512_update(&st, empty_block, sizeof empty_block);
crypto_hash_sha512_update(&st, msg, msg_len);
crypto_hash_sha512_update(&st, t, 3U);
crypto_hash_sha512_update(&st, (const unsigned char *) ctx, ctx_len);
crypto_hash_sha512_update(&st, &ctx_len_u8, 1U);
crypto_hash_sha512_final(&st, u0);
t[2]++;
crypto_hash_sha512_init(&st);
crypto_hash_sha512_update(&st, u0, HASH_BYTES);
crypto_hash_sha512_update(&st, &t[2], 1U);
crypto_hash_sha512_update(&st, (const unsigned char *) ctx, ctx_len);
crypto_hash_sha512_update(&st, &ctx_len_u8, 1U);
crypto_hash_sha512_final(&st, u0);
COMPILER_ASSERT(crypto_core_ristretto255_HASHBYTES == HASH_L);
ristretto255_from_hash(p, u0);
return 0;
}
int
crypto_core_risretto255_from_string(unsigned char p[crypto_core_ristretto255_BYTES],
const char *ctx, const unsigned char *msg,
size_t msg_len)
{
return _string_to_element(p, ctx, msg, msg_len);
}
int
crypto_core_ristretto255_from_string_ro(unsigned char p[crypto_core_ristretto255_BYTES],
const char *ctx, const unsigned char *msg,
size_t msg_len)
{
return crypto_core_risretto255_from_string(p, ctx, msg, msg_len);
}
void
crypto_core_ristretto255_random(unsigned char *p)
{

14
src/libsodium/include/sodium/crypto_core_ristretto255.h
View File

@ -43,6 +43,20 @@ int crypto_core_ristretto255_from_hash(unsigned char *p,
const unsigned char *r)
__attribute__ ((nonnull));
SODIUM_EXPORT
int crypto_core_ristretto255_from_string(unsigned char p[crypto_core_ristretto255_BYTES],
const char *ctx,
const unsigned char *msg,
size_t msg_len)
__attribute__ ((nonnull(1)));
SODIUM_EXPORT
int crypto_core_ristretto255_from_string_ro(unsigned char p[crypto_core_ristretto255_BYTES],
const char *ctx,
const unsigned char *msg,
size_t msg_len)
__attribute__ ((nonnull(1)));
SODIUM_EXPORT
void crypto_core_ristretto255_random(unsigned char *p)
__attribute__ ((nonnull));