diff options
| -rw-r--r-- | src/libstrongswan/crypto/rsa/rsa_private_key.c | 63 |
1 files changed, 41 insertions, 22 deletions
diff --git a/src/libstrongswan/crypto/rsa/rsa_private_key.c b/src/libstrongswan/crypto/rsa/rsa_private_key.c index 5bea17234..3b9494f4b 100644 --- a/src/libstrongswan/crypto/rsa/rsa_private_key.c +++ b/src/libstrongswan/crypto/rsa/rsa_private_key.c @@ -186,6 +186,26 @@ static const asn1Object_t privkey_objects[] = { static private_rsa_private_key_t *rsa_private_key_create_empty(void); /** + * Auxiliary function overwriting private key material with + * pseudo-random bytes before releasing it + */ +static mpz_clear_randomized(mpz_t z) +{ + size_t len = mpz_size(z) * GMP_LIMB_BITS / BITS_PER_BYTE; + u_int8_t *random_bytes = alloca(len); + + randomizer_t *randomizer = randomizer_create(); + + randomizer->get_pseudo_random_bytes(randomizer, len, random_bytes); + + /* overwrite mpz_t with pseudo-random bytes before clearing it */ + mpz_import(z, len, 1, 1, 1, 0, random_bytes); + mpz_clear(z); + + randomizer->destroy(randomizer); +} + +/** * Implementation of private_rsa_private_key_t.compute_prime. */ static status_t compute_prime(private_rsa_private_key_t *this, size_t prime_size, mpz_t *prime) @@ -216,7 +236,8 @@ static status_t compute_prime(private_rsa_private_key_t *this, size_t prime_size /* get next prime */ mpz_nextprime (*prime, *prime); - free(random_bytes.ptr); + /* free the random_bytes after overwriting them with a pseudo-random sequence */ + chunk_free_randomized(&random_bytes); } /* check if it isnt too large */ while (((mpz_sizeinbase(*prime, 2) + 7) / 8) > prime_size); @@ -251,8 +272,8 @@ static chunk_t rsadp(private_rsa_private_key_t *this, chunk_t data) decrypted.len = this->k; decrypted.ptr = mpz_export(NULL, NULL, 1, decrypted.len, 1, 0, t1); - mpz_clear(t1); - mpz_clear(t2); + mpz_clear_randomized(t1); + mpz_clear_randomized(t2); return decrypted; } @@ -510,9 +531,9 @@ static status_t check(private_rsa_private_key_t *this) status = FAILED; } - mpz_clear(t); - mpz_clear(u); - mpz_clear(q1); + mpz_clear_randomized(t); + mpz_clear_randomized(u); + mpz_clear_randomized(q1); return status; } @@ -542,15 +563,15 @@ static rsa_private_key_t* _clone(private_rsa_private_key_t *this) */ static void destroy(private_rsa_private_key_t *this) { - mpz_clear(this->n); - mpz_clear(this->e); - mpz_clear(this->p); - mpz_clear(this->q); - mpz_clear(this->d); - mpz_clear(this->exp1); - mpz_clear(this->exp2); - mpz_clear(this->coeff); - free(this->keyid.ptr); + mpz_clear_randomized(this->n); + mpz_clear_randomized(this->e); + mpz_clear_randomized(this->p); + mpz_clear_randomized(this->q); + mpz_clear_randomized(this->d); + mpz_clear_randomized(this->exp1); + mpz_clear_randomized(this->exp2); + mpz_clear_randomized(this->coeff); + chunk_free_randomized(&this->keyid); free(this); } @@ -615,9 +636,7 @@ rsa_private_key_t *rsa_private_key_create(size_t key_size) /* Swapping Primes so p is larger then q */ if (mpz_cmp(p, q) < 0) { - mpz_set(t, p); - mpz_set(p, q); - mpz_set(q, t); + mpz_swap(p, q); } mpz_mul(n, p, q); /* n = p*q */ @@ -647,9 +666,9 @@ rsa_private_key_t *rsa_private_key_create(size_t key_size) mpz_add(coeff, coeff, p); } - mpz_clear(q1); - mpz_clear(m); - mpz_clear(t); + mpz_clear_randomized(q1); + mpz_clear_randomized(m); + mpz_clear_randomized(t); /* apply values */ *(this->p) = *p; @@ -771,6 +790,6 @@ rsa_private_key_t *rsa_private_key_create_from_file(char *filename, chunk_t *pas return NULL; key = rsa_private_key_create_from_chunk(chunk); - free(chunk.ptr); + chunk_free_randomized(&chunk); return key; } |