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Add a function to compute an XOF in one shot.

Browse Source 
Motivation:
  1. It's convenient.
  2. It's all that openssl supports.

Part of 28837.
This commit is contained in:
Nick Mathewson 2018-12-13 16:59:04 -05:00
parent c393171403
commit 9b0dd1ae04
3 changed files with 31 additions and 0 deletions
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24
src/lib/crypt_ops/crypto_digest.c
View File

@ -955,3 +955,27 @@ crypto_xof_free_(crypto_xof_t *xof)
memwipe(xof, 0, sizeof(crypto_xof_t));
tor_free(xof);
}
/** Compute the XOF (SHAKE256) of a <b>input_len</b> bytes at <b>input</b>,
* putting <b>output_len</b> bytes at <b>output</b>. */
void
crypto_xof(uint8_t *output, size_t output_len,
const uint8_t *input, size_t input_len)
{
#ifdef OPENSSL_HAS_SHA3
EVP_MD_CTX *ctx = EVP_MD_CTX_new();
tor_assert(ctx);
int r = EVP_DigestInit(ctx, EVP_shake256());
tor_assert(r == 1);
r = EVP_DigestUpdate(ctx, input, input_len);
tor_assert(r == 1);
r = EVP_DigestFinalXOF(ctx, output, output_len);
tor_assert(r == 1);
EVP_MD_CTX_free(ctx);
#else
crypto_xof_t *xof = crypto_xof_new();
crypto_xof_add_bytes(xof, input, input_len);
crypto_xof_squeeze_bytes(xof, output, output_len);
crypto_xof_free(xof);
#endif
}

2
src/lib/crypt_ops/crypto_digest.h
View File

@ -124,6 +124,8 @@ void crypto_xof_squeeze_bytes(crypto_xof_t *xof, uint8_t *out, size_t len);
void crypto_xof_free_(crypto_xof_t *xof);
#define crypto_xof_free(xof) \
FREE_AND_NULL(crypto_xof_t, crypto_xof_free_, (xof))
void crypto_xof(uint8_t *output, size_t output_len,
const uint8_t *input, size_t input_len);
#ifdef TOR_UNIT_TESTS
digest_algorithm_t crypto_digest_get_algorithm(crypto_digest_t *digest);

5
src/test/test_crypto.c
View File

@ -1173,6 +1173,11 @@ test_crypto_sha3_xof(void *arg)
crypto_xof_free(xof);
memset(out, 0, sizeof(out));
/* Test one-function absorb/squeeze. */
crypto_xof(out, sizeof(out), msg, sizeof(msg));
test_memeq_hex(out, squeezed_hex);
memset(out, 0, sizeof(out));
/* Test incremental absorb/squeeze. */
xof = crypto_xof_new();
tt_assert(xof);