From 60cce0124f2fc3eddca03ed3950da9238247a612 Mon Sep 17 00:00:00 2001 From: Rob Austein Date: Sat, 3 Oct 2015 18:12:20 -0400 Subject: Use initializers for automatic variables of type fp_int because it's a bit more obvious when we've forgotten to do this than when we've forgotten to call fp_init() or memset(). Convert rsa.c to use the one-element-array idiom so we can get stop prefixing every bignum reference with "&". --- rsa.c | 188 ++++++++++++++++++++++++++++++++++-------------------------------- 1 file changed, 98 insertions(+), 90 deletions(-) (limited to 'rsa.c') diff --git a/rsa.c b/rsa.c index 3962a74..2483509 100644 --- a/rsa.c +++ b/rsa.c @@ -53,6 +53,10 @@ * configured to know about the largest bignum one wants it to be able * to support at compile time. This should not be a serious problem. * + * We use a lot of one-element arrays (fp_int[1] instead of plain + * fp_int) to avoid having to prefix every use of an fp_int with "&". + * Perhaps we should encapsulate this idiom in a typedef. + * * Unfortunately, libtfm is bad about const-ification, but we want to * hide that from our users, so our public API uses const as * appropriate and we use inline functions to remove const constraints @@ -110,18 +114,27 @@ void hal_rsa_set_blinding(const int onoff) struct hal_rsa_key { hal_rsa_key_type_t type; /* What kind of key this is */ - fp_int n; /* The modulus */ - fp_int e; /* Public exponent */ - fp_int d; /* Private exponent */ - fp_int p; /* 1st prime factor */ - fp_int q; /* 2nd prime factor */ - fp_int u; /* 1/q mod p */ - fp_int dP; /* d mod (p - 1) */ - fp_int dQ; /* d mod (q - 1) */ + fp_int n[1]; /* The modulus */ + fp_int e[1]; /* Public exponent */ + fp_int d[1]; /* Private exponent */ + fp_int p[1]; /* 1st prime factor */ + fp_int q[1]; /* 2nd prime factor */ + fp_int u[1]; /* 1/q mod p */ + fp_int dP[1]; /* d mod (p - 1) */ + fp_int dQ[1]; /* d mod (q - 1) */ }; const size_t hal_rsa_key_t_size = sizeof(hal_rsa_key_t); +/* + * Initializers. We want to be able to initialize automatic fp_int + * variables a sane value (less error prone), but picky compilers + * whine about the number of curly braces required. So we define a + * macro which isolates that madness in one place. + */ + +#define INIT_FP_INT {{{0}}} + /* * Error handling. */ @@ -178,12 +191,12 @@ static hal_error_t modexp(const fp_int * msg, assert(msg != NULL && exp != NULL && mod != NULL && res != NULL); - fp_int reduced_msg; + fp_int reduced_msg[1] = INIT_FP_INT; if (fp_cmp_mag(unconst_fp_int(msg), unconst_fp_int(mod)) != FP_LT) { - fp_init(&reduced_msg); - fp_mod(unconst_fp_int(msg), unconst_fp_int(mod), &reduced_msg); - msg = &reduced_msg; + fp_init(reduced_msg); + fp_mod(unconst_fp_int(msg), unconst_fp_int(mod), reduced_msg); + msg = reduced_msg; } const size_t exp_len = (fp_unsigned_bin_size(unconst_fp_int(exp)) + 3) & ~3; @@ -258,7 +271,7 @@ static hal_error_t create_blinding_factors(const hal_rsa_key_t * const key, fp_i { assert(key != NULL && bf != NULL && ubf != NULL); - uint8_t rnd[fp_unsigned_bin_size(unconst_fp_int(&key->n))]; + uint8_t rnd[fp_unsigned_bin_size(unconst_fp_int(key->n))]; hal_error_t err = HAL_OK; if ((err = hal_get_random(rnd, sizeof(rnd))) != HAL_OK) @@ -268,10 +281,10 @@ static hal_error_t create_blinding_factors(const hal_rsa_key_t * const key, fp_i fp_read_unsigned_bin(bf, rnd, sizeof(rnd)); fp_copy(bf, ubf); - if ((err = modexp(bf, &key->e, &key->n, bf)) != HAL_OK) + if ((err = modexp(bf, key->e, key->n, bf)) != HAL_OK) goto fail; - FP_CHECK(fp_invmod(ubf, unconst_fp_int(&key->n), ubf)); + FP_CHECK(fp_invmod(ubf, unconst_fp_int(key->n), ubf)); fail: memset(rnd, 0, sizeof(rnd)); @@ -287,62 +300,62 @@ static hal_error_t rsa_crt(const hal_rsa_key_t * const key, fp_int *msg, fp_int assert(key != NULL && msg != NULL && sig != NULL); hal_error_t err = HAL_OK; - fp_int t, m1, m2, bf, ubf; - - fp_init(&t); - fp_init(&m1); - fp_init(&m2); + fp_int t[1] = INIT_FP_INT; + fp_int m1[1] = INIT_FP_INT; + fp_int m2[1] = INIT_FP_INT; + fp_int bf[1] = INIT_FP_INT; + fp_int ubf[1] = INIT_FP_INT; /* * Handle blinding if requested. */ if (blinding) { - if ((err = create_blinding_factors(key, &bf, &ubf)) != HAL_OK) + if ((err = create_blinding_factors(key, bf, ubf)) != HAL_OK) goto fail; - FP_CHECK(fp_mulmod(msg, &bf, unconst_fp_int(&key->n), msg)); + FP_CHECK(fp_mulmod(msg, bf, unconst_fp_int(key->n), msg)); } /* * m1 = msg ** dP mod p * m2 = msg ** dQ mod q */ - if ((err = modexp(msg, &key->dP, &key->p, &m1)) != HAL_OK || - (err = modexp(msg, &key->dQ, &key->q, &m2)) != HAL_OK) + if ((err = modexp(msg, key->dP, key->p, m1)) != HAL_OK || + (err = modexp(msg, key->dQ, key->q, m2)) != HAL_OK) goto fail; /* * t = m1 - m2. */ - fp_sub(&m1, &m2, &t); + fp_sub(m1, m2, t); /* * Add zero (mod p) if needed to make t positive. If doing this * once or twice doesn't help, something is very wrong. */ - if (fp_cmp_d(&t, 0) == FP_LT) - fp_add(&t, unconst_fp_int(&key->p), &t); - if (fp_cmp_d(&t, 0) == FP_LT) - fp_add(&t, unconst_fp_int(&key->p), &t); - if (fp_cmp_d(&t, 0) == FP_LT) + if (fp_cmp_d(t, 0) == FP_LT) + fp_add(t, unconst_fp_int(key->p), t); + if (fp_cmp_d(t, 0) == FP_LT) + fp_add(t, unconst_fp_int(key->p), t); + if (fp_cmp_d(t, 0) == FP_LT) lose(HAL_ERROR_IMPOSSIBLE); /* * sig = (t * u mod p) * q + m2 */ - FP_CHECK(fp_mulmod(&t, unconst_fp_int(&key->u), unconst_fp_int(&key->p), &t)); - fp_mul(&t, unconst_fp_int(&key->q), &t); - fp_add(&t, &m2, sig); + FP_CHECK(fp_mulmod(t, unconst_fp_int(key->u), unconst_fp_int(key->p), t)); + fp_mul(t, unconst_fp_int(key->q), t); + fp_add(t, m2, sig); /* * Unblind if necessary. */ if (blinding) - FP_CHECK(fp_mulmod(sig, &ubf, unconst_fp_int(&key->n), sig)); + FP_CHECK(fp_mulmod(sig, ubf, unconst_fp_int(key->n), sig)); fail: - fp_zero(&t); - fp_zero(&m1); - fp_zero(&m2); + fp_zero(t); + fp_zero(m1); + fp_zero(m2); return err; } @@ -362,19 +375,18 @@ hal_error_t hal_rsa_encrypt(const hal_rsa_key_t * const key, if (key == NULL || input == NULL || output == NULL || input_len > output_len) return HAL_ERROR_BAD_ARGUMENTS; - fp_int i, o; - fp_init(&i); - fp_init(&o); + fp_int i[1] = INIT_FP_INT; + fp_int o[1] = INIT_FP_INT; - fp_read_unsigned_bin(&i, unconst_uint8_t(input), input_len); + fp_read_unsigned_bin(i, unconst_uint8_t(input), input_len); - if ((err = modexp(&i, &key->e, &key->n, &o)) != HAL_OK || - (err = unpack_fp(&o, output, output_len)) != HAL_OK) + if ((err = modexp(i, key->e, key->n, o)) != HAL_OK || + (err = unpack_fp(o, output, output_len)) != HAL_OK) goto fail; fail: - fp_zero(&i); - fp_zero(&o); + fp_zero(i); + fp_zero(o); return err; } @@ -387,28 +399,27 @@ hal_error_t hal_rsa_decrypt(const hal_rsa_key_t * const key, if (key == NULL || input == NULL || output == NULL || input_len > output_len) return HAL_ERROR_BAD_ARGUMENTS; - fp_int i, o; - fp_init(&i); - fp_init(&o); + fp_int i[1] = INIT_FP_INT; + fp_int o[1] = INIT_FP_INT; - fp_read_unsigned_bin(&i, unconst_uint8_t(input), input_len); + fp_read_unsigned_bin(i, unconst_uint8_t(input), input_len); /* * Do CRT if we have all the necessary key components, otherwise * just do brute force ModExp. */ - if (fp_iszero(&key->p) || fp_iszero(&key->q) || fp_iszero(&key->u) || fp_iszero(&key->dP) || fp_iszero(&key->dQ)) - err = modexp(&i, &key->d, &key->n, &o); + if (fp_iszero(key->p) || fp_iszero(key->q) || fp_iszero(key->u) || fp_iszero(key->dP) || fp_iszero(key->dQ)) + err = modexp(i, key->d, key->n, o); else - err = rsa_crt(key, &i, &o); + err = rsa_crt(key, i, o); - if (err != HAL_OK || (err = unpack_fp(&o, output, output_len)) != HAL_OK) + if (err != HAL_OK || (err = unpack_fp(o, output, output_len)) != HAL_OK) goto fail; fail: - fp_zero(&i); - fp_zero(&o); + fp_zero(i); + fp_zero(o); return err; } @@ -454,7 +465,7 @@ static hal_error_t load_key(const hal_rsa_key_type_t type, key->type = type; -#define _(x) do { fp_init(&key->x); if (x == NULL) goto fail; fp_read_unsigned_bin(&key->x, unconst_uint8_t(x), x##_len); } while (0) +#define _(x) do { fp_init(key->x); if (x == NULL) goto fail; fp_read_unsigned_bin(key->x, unconst_uint8_t(x), x##_len); } while (0) switch (type) { case HAL_RSA_PRIVATE: _(d); _(p); _(q); _(u); _(dP); _(dQ); @@ -569,9 +580,7 @@ static hal_error_t find_prime(const unsigned prime_length, { uint8_t buffer[prime_length]; hal_error_t err; - fp_int t; - - fp_init(&t); + fp_int t[1] = INIT_FP_INT; do { if ((err = hal_get_random(buffer, sizeof(buffer))) != HAL_OK) @@ -581,9 +590,9 @@ static hal_error_t find_prime(const unsigned prime_length, fp_read_unsigned_bin(result, buffer, sizeof(buffer)); } while (!fp_isprime(result) || - (fp_sub_d(result, 1, &t), fp_gcd(&t, unconst_fp_int(e), &t), fp_cmp_d(&t, 1) != FP_EQ)); + (fp_sub_d(result, 1, t), fp_gcd(t, unconst_fp_int(e), t), fp_cmp_d(t, 1) != FP_EQ)); - fp_zero(&t); + fp_zero(t); return HAL_OK; } @@ -598,41 +607,42 @@ hal_error_t hal_rsa_key_gen(hal_rsa_key_t **key_, { hal_rsa_key_t *key = keybuf; hal_error_t err = HAL_OK; - fp_int p_1, q_1; + fp_int p_1[1] = INIT_FP_INT; + fp_int q_1[1] = INIT_FP_INT; if (key_ == NULL || keybuf == NULL || keybuf_len < sizeof(hal_rsa_key_t)) return HAL_ERROR_BAD_ARGUMENTS; memset(keybuf, 0, keybuf_len); key->type = HAL_RSA_PRIVATE; - fp_read_unsigned_bin(&key->e, (uint8_t *) public_exponent, public_exponent_len); + fp_read_unsigned_bin(key->e, (uint8_t *) public_exponent, public_exponent_len); if (key_length < bitsToBytes(1024) || key_length > bitsToBytes(8192)) return HAL_ERROR_UNSUPPORTED_KEY; - if (fp_cmp_d(&key->e, 0x010001) != FP_EQ) + if (fp_cmp_d(key->e, 0x010001) != FP_EQ) return HAL_ERROR_UNSUPPORTED_KEY; /* * Find a good pair of prime numbers. */ - if ((err = find_prime(key_length / 2, &key->e, &key->p)) != HAL_OK || - (err = find_prime(key_length / 2, &key->e, &key->q)) != HAL_OK) + if ((err = find_prime(key_length / 2, key->e, key->p)) != HAL_OK || + (err = find_prime(key_length / 2, key->e, key->q)) != HAL_OK) return err; /* * Calculate remaining key components. */ - fp_init(&p_1); fp_sub_d(&key->p, 1, &p_1); - fp_init(&q_1); fp_sub_d(&key->q, 1, &q_1); - fp_mul(&key->p, &key->q, &key->n); /* n = p * q */ - fp_lcm(&p_1, &q_1, &key->d); - FP_CHECK(fp_invmod(&key->e, &key->d, &key->d)); /* d = (1/e) % lcm(p-1, q-1) */ - FP_CHECK(fp_mod(&key->d, &p_1, &key->dP)); /* dP = d % (p-1) */ - FP_CHECK(fp_mod(&key->d, &q_1, &key->dQ)); /* dQ = d % (q-1) */ - FP_CHECK(fp_invmod(&key->q, &key->p, &key->u)); /* u = (1/q) % p */ + fp_init(p_1); fp_sub_d(key->p, 1, p_1); + fp_init(q_1); fp_sub_d(key->q, 1, q_1); + fp_mul(key->p, key->q, key->n); /* n = p * q */ + fp_lcm(p_1, q_1, key->d); + FP_CHECK(fp_invmod(key->e, key->d, key->d)); /* d = (1/e) % lcm(p-1, q-1) */ + FP_CHECK(fp_mod(key->d, p_1, key->dP)); /* dP = d % (p-1) */ + FP_CHECK(fp_mod(key->d, q_1, key->dQ)); /* dQ = d % (q-1) */ + FP_CHECK(fp_invmod(key->q, key->p, key->u)); /* u = (1/q) % p */ *key_ = key; @@ -641,8 +651,8 @@ hal_error_t hal_rsa_key_gen(hal_rsa_key_t **key_, fail: if (err != HAL_OK) memset(keybuf, 0, keybuf_len); - fp_zero(&p_1); - fp_zero(&q_1); + fp_zero(p_1); + fp_zero(q_1); return err; } @@ -654,15 +664,15 @@ hal_error_t hal_rsa_key_gen(hal_rsa_key_t **key_, */ #define RSAPrivateKey_fields \ - _(&version); \ - _(&key->n); \ - _(&key->e); \ - _(&key->d); \ - _(&key->p); \ - _(&key->q); \ - _(&key->dP); \ - _(&key->dQ); \ - _(&key->u); + _(version); \ + _(key->n); \ + _(key->e); \ + _(key->d); \ + _(key->p); \ + _(key->q); \ + _(key->dP); \ + _(key->dQ); \ + _(key->u); hal_error_t hal_rsa_key_to_der(const hal_rsa_key_t * const key, uint8_t *der, size_t *der_len, const size_t der_max) @@ -672,8 +682,7 @@ hal_error_t hal_rsa_key_to_der(const hal_rsa_key_t * const key, if (key == NULL || der_len == NULL || key->type != HAL_RSA_PRIVATE) return HAL_ERROR_BAD_ARGUMENTS; - fp_int version; - fp_zero(&version); + fp_int version[1] = INIT_FP_INT; /* * Calculate data length. @@ -738,14 +747,13 @@ hal_error_t hal_rsa_key_from_der(hal_rsa_key_t **key_, der += hlen; - fp_int version; - fp_init(&version); + fp_int version[1] = INIT_FP_INT; #define _(x) { size_t i; if ((err = hal_asn1_decode_integer(x, der, &i, vlen)) != HAL_OK) return err; der += i; vlen -= i; } RSAPrivateKey_fields; #undef _ - if (fp_cmp_d(&version, 0) != FP_EQ) + if (fp_cmp_d(version, 0) != FP_EQ) return HAL_ERROR_ASN1_PARSE_FAILED; *key_ = key; -- cgit v1.2.3