/*
* Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/*
* For the prime check..
* FIPS 186-4 Section C.3 Table C.1
* Returns the minimum number of Miller Rabin iterations for a L,N pair
* (where L = len(p), N = len(q))
* L N Min
* 1024 160 40
* 2048 224 56
* 2048 256 56
* 3072 256 64
*
* BN_check_prime() uses:
* 64 iterations for L <= 2048 OR
* 128 iterations for L > 2048
* So this satisfies the requirement.
*/
#include <string.h> /* memset */
#include <openssl/sha.h> /* SHA_DIGEST_LENGTH */
#include <openssl/rand.h>
#include <openssl/err.h>
#include <openssl/dherr.h>
#include <openssl/dsaerr.h>
#include "crypto/bn.h"
#include "internal/ffc.h"
/*
* Verify that the passed in L, N pair for DH or DSA is valid.
* Returns 0 if invalid, otherwise it returns the security strength.
*/
#ifdef FIPS_MODULE
static int ffc_validate_LN(size_t L, size_t N, int type, int verify)
{
if (type == FFC_PARAM_TYPE_DH) {
/* Valid DH L,N parameters from SP800-56Ar3 5.5.1 Table 1 */
if (L == 2048 && (N == 224 || N == 256))
return 112;
# ifndef OPENSSL_NO_DH
ERR_raise(ERR_LIB_DH, DH_R_BAD_FFC_PARAMETERS);
# endif
} else if (type == FFC_PARAM_TYPE_DSA) {
/* Valid DSA L,N parameters from FIPS 186-4 Section 4.2 */
/* In fips mode 1024/160 can only be used for verification */
if (verify && L == 1024 && N == 160)
return 80;
if (L == 2048 && (N == 224 || N == 256))
return 112;
if (L == 3072 && N == 256)
return 128;
# ifndef OPENSSL_NO_DSA
ERR_raise(ERR_LIB_DSA, DSA_R_BAD_FFC_PARAMETERS);
# endif
}
return 0;
}
#else
static int ffc_validate_LN(size_t L, size_t N, int type, int verify)
{
if (type == FFC_PARAM_TYPE_DH) {
/* Allow legacy 1024/160 in non fips mode */
if (L == 1024 && N == 160)
return 80;
/* Valid DH L,N parameters from SP800-56Ar3 5.5.1 Table 1 */
if (L == 2048 && (N == 224 || N == 256))
return 112;
# ifndef OPENSSL_NO_DH
ERR_raise(ERR_LIB_DH, DH_R_BAD_FFC_PARAMETERS);
# endif
} else if (type == FFC_PARAM_TYPE_DSA) {
if (L >= 3072 && N >= 256)
return 128;
if (L >= 2048 && N >= 224)
return 112;
if (L >= 1024 && N >= 160)
return 80;
# ifndef OPENSSL_NO_DSA
ERR_raise(ERR_LIB_DSA, DSA_R_BAD_FFC_PARAMETERS);
# endif
}
return 0;
}
#endif /* FIPS_MODULE */
/* FIPS186-4 A.2.1 Unverifiable Generation of Generator g */
static int generate_unverifiable_g(BN_CTX *ctx, BN_MONT_CTX *mont, BIGNUM *g,
BIGNUM *hbn, const BIGNUM *p,
const BIGNUM *e,const BIGNUM *pm1,
int *hret)
{
int h = 2;
/* Step (2): choose h (where 1 < h)*/
if (!BN_set_word(hbn, h))
return 0;
for (;;) {
/* Step (3): g = h^e % p */
if (!BN_mod_exp_mont(g, hbn, e, p, ctx, mont))
return 0;
/* Step (4): Finish if g > 1 */
if (BN_cmp(g, BN_value_one()) > 0)
break;
/* Step (2) Choose any h in the range 1 < h < (p-1) */
if (!BN_add_word(hbn, 1) || BN_cmp(hbn, pm1) >= 0)
return 0;
++h;
}
*hret = h;
return 1;
}
/*
* FIPS186-4 A.2 Generation of canonical generator g.
*
* It requires the following values as input:
* 'evpmd' digest, 'p' prime, 'e' cofactor, gindex and seed.
* tmp is a passed in temporary BIGNUM.
* mont is used in a BN_mod_exp_mont() with a modulus of p.
* Returns a value in g.
*/
static int generate_canonical_g(BN_CTX *ctx, BN_MONT_CTX *mont,
const EVP_MD *evpmd, BIGNUM *g, BIGNUM *tmp,
const BIGNUM *p, const BIGNUM *e,
int gindex, unsigned char *seed, size_t seedlen)
{
int ret = 0;
int counter = 1;
unsigned char md[EVP_MAX_MD_SIZE];
EVP_MD_CTX *mctx = NULL;
int mdsize;
mdsize = EVP_MD_size(evpmd);
if (mdsize <= 0)
return 0;
mctx = EVP_MD_CTX_new();
if (mctx == NULL)
return 0;
/*
* A.2.3 Step (4) & (5)
* A.2.4 Step (6) & (7)
* counter = 0; counter += 1
*/
for (counter = 1; counter <= 0xFFFF; ++counter) {
/*
* A.2.3 Step (7) & (8) & (9)
* A.2.4 Step (9) & (10) & (11)
* W = Hash(seed || "ggen" || index || counter)
* g = W^e % p
*/
static const unsigned char ggen[4] = { 0x67, 0x67, 0x65, 0x6e };
md[0] = (unsigned char)(gindex & 0xff);
md[1] = (unsigned char)((counter >> 8) & 0xff);
md[2] = (unsigned char)(counter & 0xff);
if (!EVP_DigestInit_ex(mctx, evpmd, NULL)
|| !EVP_DigestUpdate(mctx, seed, seedlen)
|| !EVP_DigestUpdate(mctx, ggen, sizeof(ggen))
|| !EVP_DigestUpdate(mctx, md, 3)
|| !EVP_DigestFinal_ex(mctx, md, NULL)
|| (BN_bin2bn(md, mdsize, tmp) == NULL)
|| !BN_mod_exp_mont(g, tmp, e, p, ctx, mont))
break; /* exit on failure */
/*
* A.2.3 Step (10)
* A.2.4 Step (12)
* Found a value for g if (g >= 2)
*/
if (BN_cmp(g, BN_value_one()) > 0) {
ret = 1;
break; /* found g */
}
}
EVP_MD_CTX_free(mctx);
return ret;
}
/* Generation of p is the same for FIPS 186-4 & FIPS 186-2 */
static int generate_p(BN_CTX *ctx, const EVP_MD *evpmd, int max_counter, int n,
unsigned char *buf, size_t buf_len, const BIGNUM *q,
BIGNUM *p, int L, BN_GENCB *cb, int *counter,
int *res)
{
int ret = -1;
int i, j, k, r;
unsigned char md[EVP_MAX_MD_SIZE];
int mdsize;
BIGNUM *W, *X, *tmp, *c, *test;
BN_CTX_start(ctx);
W = BN_CTX_get(ctx);
X = BN_CTX_get(ctx);
c = BN_CTX_get(ctx);
test = BN_CTX_get(ctx);
tmp = BN_CTX_get(ctx);
if (tmp == NULL)
goto err;
if (!BN_lshift(test, BN_value_one(), L - 1))
goto err;
mdsize = EVP_MD_size(evpmd);
if (mdsize <= 0)
goto err;
/* A.1.1.2 Step (10) AND
* A.1.1.2 Step (12)
* offset = 1 (this is handled below)
*/
/*
* A.1.1.2 Step (11) AND
* A.1.1.3 Step (13)
*/
for (i = 0; i <= max_counter; i++) {
if ((i != 0) && !BN_GENCB_call(cb, 0, i))
goto err;
BN_zero(W);
/* seed_tmp buffer contains "seed + offset - 1" */
for (j = 0; j <= n; j++) {
/* obtain "seed + offset + j" by incrementing by 1: */
for (k = (int)buf_len - 1; k >= 0; k--) {
buf[k]++;
if (buf[k] != 0)
break;
}
/*
* A.1.1.2 Step (11.1) AND
* A.1.1.3 Step (13.1)
* tmp = V(j) = Hash((seed + offset + j) % 2^seedlen)
*/
if (!EVP_Digest(buf, buf_len, md, NULL, evpmd, NULL)
|| (BN_bin2bn(md, mdsize, tmp) == NULL)
/*
* A.1.1.2 Step (11.2)
* A.1.1.3 Step (13.2)
* W += V(j) * 2^(outlen * j)
*/
|| !BN_lshift(tmp, tmp, (mdsize << 3) * j)
|| !BN_add(W, W, tmp))
goto err;
}
/*
* A.1.1.2 Step (11.3) AND
* A.1.1.3 Step (13.3)
* X = W + 2^(L-1) where W < 2^(L-1)
*/
if (!BN_mask_bits(W, L - 1)
|| !BN_copy(X, W)
|| !BN_add(X, X, test)
/*
* A.1.1.2 Step (11.4) AND
* A.1.1.3 Step (13.4)
* c = X mod 2q
*/
|| !BN_lshift1(tmp, q)
|| !BN_mod(c, X, tmp, ctx)
/*
* A.1.1.2 Step (11.5) AND
* A.1.1.3 Step (13.5)
* p = X - (c - 1)
*/
|| !BN_sub(tmp, c, BN_value_one())
|| !BN_sub(p, X, tmp))
goto err;
/*
* A.1.1.2 Step (11.6) AND
* A.1.1.3 Step (13.6)
* if (p < 2 ^ (L-1)) continue
* This makes sure the top bit is set.
*/
if (BN_cmp(p, test) >= 0) {
/*
* A.1.1.2 Step (11.7) AND
* A.1.1.3 Step (13.7)
* Test if p is prime
* (This also makes sure the bottom bit is set)
*/
r = BN_check_prime(p, ctx, cb);
/* A.1.1.2 Step (11.8) : Return if p is prime */
if (r > 0) {
*counter = i;
ret = 1; /* return success */
goto err;
}
if (r != 0)
goto err;
}
/* Step (11.9) : offset = offset + n + 1 is done auto-magically */
}
/* No prime P found */
ret = 0;
*res |= FFC_CHECK_P_NOT_PRIME;
err:
BN_CTX_end(ctx);
return ret;
}
static int generate_q_fips186_4(BN_CTX *ctx, BIGNUM *q, const EVP_MD *evpmd,
int qsize, unsigned char *seed, size_t seedlen,
int generate_seed, int *retm, int *res,
BN_GENCB *cb)
{
int ret = 0, r;
int m = *retm;
unsigned char md[EVP_MAX_MD_SIZE];
int mdsize = EVP_MD_size(evpmd);
unsigned char *pmd;
OSSL_LIB_CTX *libctx = ossl_bn_get_libctx(ctx);
/* find q */
for (;;) {
if(!BN_GENCB_call(cb, 0, m++))
goto err;
/* A.1.1.2 Step (5) : generate seed with size seed_len */
if (generate_seed
&& RAND_bytes_ex(libctx, seed, (int)seedlen) < 0)
goto err;
/*
* A.1.1.2 Step (6) AND
* A.1.1.3 Step (7)
* U = Hash(seed) % (2^(N-1))
*/
if (!EVP_Digest(seed, seedlen, md, NULL, evpmd, NULL))
goto err;
/* Take least significant bits of md */
if (mdsize > qsize)
pmd = md + mdsize - qsize;
else
pmd = md;
if (mdsize < qsize)
memset(md + mdsize, 0, qsize - mdsize);
/*
* A.1.1.2 Step (7) AND
* A.1.1.3 Step (8)
* q = U + 2^(N-1) + (1 - U %2) (This sets top and bottom bits)
*/
pmd[0] |= 0x80;
pmd[qsize-1] |= 0x01;
if (!BN_bin2bn(pmd, qsize, q))
goto err;
/*
* A.1.1.2 Step (8) AND
* A.1.1.3 Step (9)
* Test if q is prime
*/
r = BN_check_prime(q, ctx, cb);
if (r > 0) {
ret = 1;
goto err;
}
/*
* A.1.1.3 Step (9) : If the provided seed didn't produce a prime q
* return an error.
*/
if (!generate_seed) {
*res |= FFC_CHECK_Q_NOT_PRIME;
goto err;
}
if (r != 0)
goto err;
/* A.1.1.2 Step (9) : if q is not prime, try another q */
}
err:
*retm = m;
return ret;
}
static int generate_q_fips186_2(BN_CTX *ctx, BIGNUM *q, const EVP_MD *evpmd,
unsigned char *buf, unsigned char *seed,
size_t qsize, int generate_seed, int *retm,
int *res, BN_GENCB *cb)
{
unsigned char buf2[EVP_MAX_MD_SIZE];
unsigned char md[EVP_MAX_MD_SIZE];
int i, r, ret = 0, m = *retm;
OSSL_LIB_CTX *libctx = ossl_bn_get_libctx(ctx);
/* find q */
for (;;) {
/* step 1 */
if (!BN_GENCB_call(cb, 0, m++))
goto err;
if (generate_seed && RAND_bytes_ex(libctx, seed, (int)qsize) <= 0)
goto err;
memcpy(buf, seed, qsize);
memcpy(buf2, seed, qsize);
/* precompute "SEED + 1" for step 7: */
for (i = (int)qsize - 1; i >= 0; i--) {
buf[i]++;
if (buf[i] != 0)
break;
}
/* step 2 */
if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL))
goto err;
if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL))
goto err;
for (i = 0; i < (int)qsize; i++)
md[i] ^= buf2[i];
/* step 3 */
md[0] |= 0x80;
md[qsize - 1] |= 0x01;
if (!BN_bin2bn(md, (int)qsize, q))
goto err;
/* step 4 */
r = BN_check_prime(q, ctx, cb);
if (r > 0) {
/* Found a prime */
ret = 1;
goto err;
}
if (r != 0)
goto err; /* Exit if error */
/* Try another iteration if it wasnt prime - was in old code.. */
generate_seed = 1;
}
err:
*retm = m;
return ret;
}
static const char *default_mdname(size_t N)
{
if (N == 160)
return "SHA1";
else if (N == 224)
return "SHA-224";
else if (N == 256)
return "SHA-256";
return NULL;
}
/*
* FIPS 186-4 FFC parameter generation (as defined in Appendix A).
* The same code is used for validation (when validate_flags != 0)
*
* The primes p & q are generated/validated using:
* A.1.1.2 Generation of probable primes p & q using approved hash.
* A.1.1.3 Validation of generated probable primes
*
* Generator 'g' has 2 types in FIPS 186-4:
* (1) A.2.1 unverifiable generation of generator g.
* A.2.2 Assurance of the validity of unverifiable generator g.
* (2) A.2.3 Verifiable Canonical Generation of the generator g.
* A.2.4 Validation for Canonical Generation of the generator g.
*
* Notes:
* (1) is only a partial validation of g, The validation of (2) requires
* the seed and index used during generation as input.
*
* params: used to pass in values for generation and validation.
* params->md: is the digest to use, If this value is NULL, then the digest is
* chosen using the value of N.
* params->flags:
* For validation one of:
* -FFC_PARAM_FLAG_VALIDATE_PQ
* -FFC_PARAM_FLAG_VALIDATE_G
* -FFC_PARAM_FLAG_VALIDATE_ALL
* For generation of p & q:
* - This is skipped if p & q are passed in.
* - If the seed is passed in then generation of p & q uses this seed (and if
* this fails an error will occur).
* - Otherwise the seed is generated, and values of p & q are generated and
* the value of seed and counter are optionally returned.
* For the generation of g (after the generation of p, q):
* - If the seed has been generated or passed in and a valid gindex is passed
* in then canonical generation of g is used otherwise unverifiable
* generation of g is chosen.
* For validation of p & q:
* - p, q, and the seed and counter used for generation must be passed in.
* For validation of g:
* - For a partial validation : p, q and g are required.
* - For a canonical validation : the gindex and seed used for generation are
* also required.
* mode: The mode - either FFC_PARAM_MODE_GENERATE or FFC_PARAM_MODE_VERIFY.
* type: The key type - FFC_PARAM_TYPE_DSA or FFC_PARAM_TYPE_DH.
* L: is the size of the prime p in bits (e.g 2048)
* N: is the size of the prime q in bits (e.g 256)
* res: A returned failure reason (One of FFC_CHECK_XXXX),
* or 0 for general failures.
* cb: A callback (can be NULL) that is called during different phases
*
* Returns:
* - FFC_PARAM_RET_STATUS_FAILED: if there was an error, or validation failed.
* - FFC_PARAM_RET_STATUS_SUCCESS if the generation or validation succeeded.
* - FFC_PARAM_RET_STATUS_UNVERIFIABLE_G if the validation of G succeeded,
* but G is unverifiable.
*/
int ossl_ffc_params_FIPS186_4_gen_verify(OSSL_LIB_CTX *libctx,
FFC_PARAMS *params, int mode, int type,
size_t L, size_t N, int *res,
BN_GENCB *cb)
{
int ok = FFC_PARAM_RET_STATUS_FAILED;
unsigned char *seed = NULL, *seed_tmp = NULL;
int mdsize, counter = 0, pcounter = 0, r = 0;
size_t seedlen = 0;
BIGNUM *tmp, *pm1, *e, *test;
BIGNUM *g = NULL, *q = NULL, *p = NULL;
BN_MONT_CTX *mont = NULL;
int n = 0, m = 0, qsize;
int canonical_g = 0, hret = 0;
BN_CTX *ctx = NULL;
EVP_MD_CTX *mctx = NULL;
EVP_MD *md = NULL;
int verify = (mode == FFC_PARAM_MODE_VERIFY);
unsigned int flags = verify ? params->flags : 0;
const char *def_name;
*res = 0;
if (params->mdname != NULL) {
md = EVP_MD_fetch(libctx, params->mdname, params->mdprops);
} else {
if (N == 0)
N = (L >= 2048 ? SHA256_DIGEST_LENGTH : SHA_DIGEST_LENGTH) * 8;
def_name = default_mdname(N);
if (def_name == NULL) {
*res = FFC_CHECK_INVALID_Q_VALUE;
goto err;
}
md = EVP_MD_fetch(libctx, def_name, params->mdprops);
}
if (md == NULL)
goto err;
mdsize = EVP_MD_size(md);
if (mdsize <= 0)
goto err;
if (N == 0)
N = mdsize * 8;
qsize = N >> 3;
/*
* A.1.1.2 Step (1) AND
* A.1.1.3 Step (3)
* Check that the L,N pair is an acceptable pair.
*/
if (L <= N || !ffc_validate_LN(L, N, type, verify)) {
*res = FFC_CHECK_BAD_LN_PAIR;
goto err;
}
mctx = EVP_MD_CTX_new();
if (mctx == NULL)
goto err;
if ((ctx = BN_CTX_new_ex(libctx)) == NULL)
goto err;
BN_CTX_start(ctx);
g = BN_CTX_get(ctx);
pm1 = BN_CTX_get(ctx);
e = BN_CTX_get(ctx);
test = BN_CTX_get(ctx);
tmp = BN_CTX_get(ctx);
if (tmp == NULL)
goto err;
seedlen = params->seedlen;
if (seedlen == 0)
seedlen = (size_t)mdsize;
/* If the seed was passed in - use this value as the seed */
if (params->seed != NULL)
seed = params->seed;
if (!verify) {
/* For generation: p & q must both be NULL or NON-NULL */
if ((params->p == NULL) != (params->q == NULL)) {
*res = FFC_CHECK_INVALID_PQ;
goto err;
}
} else {
/* Validation of p,q requires seed and counter to be valid */
if ((flags & FFC_PARAM_FLAG_VALIDATE_PQ) != 0) {
if (seed == NULL || params->pcounter < 0) {
*res = FFC_CHECK_MISSING_SEED_OR_COUNTER;
goto err;
}
}
if ((flags & FFC_PARAM_FLAG_VALIDATE_G) != 0) {
/* validation of g also requires g to be set */
if (params->g == NULL) {
*res = FFC_CHECK_INVALID_G;
goto err;
}
}
}
/*
* If p & q are passed in and
* validate_flags = 0 then skip the generation of PQ.
* validate_flags = VALIDATE_G then also skip the validation of PQ.
*/
if (params->p != NULL && ((flags & FFC_PARAM_FLAG_VALIDATE_PQ) == 0)) {
/* p and q already exists so only generate g */
p = params->p;
q = params->q;
goto g_only;
/* otherwise fall thru to validate p & q */
}
/* p & q will be used for generation and validation */
p = BN_CTX_get(ctx);
q = BN_CTX_get(ctx);
if (q == NULL)
goto err;
/*
* A.1.1.2 Step (2) AND
* A.1.1.3 Step (6)
* Return invalid if seedlen < N
*/
if ((seedlen * 8) < N) {
*res = FFC_CHECK_INVALID_SEED_SIZE;
goto err;
}
seed_tmp = OPENSSL_malloc(seedlen);
if (seed_tmp == NULL)
goto err;
if (seed == NULL) {
/* Validation requires the seed to be supplied */
if (verify) {
*res = FFC_CHECK_MISSING_SEED_OR_COUNTER;
goto err;
}
/* if the seed is not supplied then alloc a seed buffer */
seed = OPENSSL_malloc(seedlen);
if (seed == NULL)
goto err;
}
/* A.1.1.2 Step (11): max loop count = 4L - 1 */
counter = 4 * L - 1;
/* Validation requires the counter to be supplied */
if (verify) {
/* A.1.1.3 Step (4) : if (counter > (4L -1)) return INVALID */
if (params->pcounter > counter) {
*res = FFC_CHECK_INVALID_COUNTER;
goto err;
}
counter = params->pcounter;
}
/*
* A.1.1.2 Step (3) AND
* A.1.1.3 Step (10)
* n = floor(L / hash_outlen) - 1
*/
n = (L - 1 ) / (mdsize << 3);
/* Calculate 2^(L-1): Used in step A.1.1.2 Step (11.3) */
if (!BN_lshift(test, BN_value_one(), L - 1))
goto err;
for (;;) {
if (!generate_q_fips186_4(ctx, q, md, qsize, seed, seedlen,
seed != params->seed, &m, res, cb))
goto err;
/* A.1.1.3 Step (9): Verify that q matches the expected value */
if (verify && (BN_cmp(q, params->q) != 0)) {
*res = FFC_CHECK_Q_MISMATCH;
goto err;
}
if(!BN_GENCB_call(cb, 2, 0))
goto err;
if(!BN_GENCB_call(cb, 3, 0))
goto err;
memcpy(seed_tmp, seed, seedlen);
r = generate_p(ctx, md, counter, n, seed_tmp, seedlen, q, p, L,
cb, &pcounter, res);
if (r > 0)
break; /* found p */
if (r < 0)
goto err;
/*
* A.1.1.3 Step (14):
* If we get here we failed to get a p for the given seed. If the
* seed is not random then it needs to fail (as it will always fail).
*/
if (seed == params->seed) {
*res = FFC_CHECK_P_NOT_PRIME;
goto err;
}
}
if(!BN_GENCB_call(cb, 2, 1))
goto err;
/*
* Gets here if we found p.
* A.1.1.3 Step (14): return error if i != counter OR computed_p != known_p.
*/
if (verify && (pcounter != counter || (BN_cmp(p, params->p) != 0)))
goto err;
/* If validating p & q only then skip the g validation test */
if ((flags & FFC_PARAM_FLAG_VALIDATE_ALL) == FFC_PARAM_FLAG_VALIDATE_PQ)
goto pass;
g_only:
if ((mont = BN_MONT_CTX_new()) == NULL)
goto err;
if (!BN_MONT_CTX_set(mont, p, ctx))
goto err;
if (((flags & FFC_PARAM_FLAG_VALIDATE_G) != 0)
&& !ossl_ffc_params_validate_unverifiable_g(ctx, mont, p, q, params->g,
tmp, res))
goto err;
/*
* A.2.1 Step (1) AND
* A.2.3 Step (3) AND
* A.2.4 Step (5)
* e = (p - 1) / q (i.e- Cofactor 'e' is given by p = q * e + 1)
*/
if (!(BN_sub(pm1, p, BN_value_one()) && BN_div(e, NULL, pm1, q, ctx)))
goto err;
/* Canonical g requires a seed and index to be set */
if ((seed != NULL) && (params->gindex != FFC_UNVERIFIABLE_GINDEX)) {
canonical_g = 1;
if (!generate_canonical_g(ctx, mont, md, g, tmp, p, e,
params->gindex, seed, seedlen)) {
*res = FFC_CHECK_INVALID_G;
goto err;
}
/* A.2.4 Step (13): Return valid if computed_g == g */
if (verify && BN_cmp(g, params->g) != 0) {
*res = FFC_CHECK_G_MISMATCH;
goto err;
}
} else if (!verify) {
if (!generate_unverifiable_g(ctx, mont, g, tmp, p, e, pm1, &hret))
goto err;
}
if (!BN_GENCB_call(cb, 3, 1))
goto err;
if (!verify) {
if (p != params->p) {
BN_free(params->p);
params->p = BN_dup(p);
}
if (q != params->q) {
BN_free(params->q);
params->q = BN_dup(q);
}
if (g != params->g) {
BN_free(params->g);
params->g = BN_dup(g);
}
if (params->p == NULL || params->q == NULL || params->g == NULL)
goto err;
if (!ossl_ffc_params_set_validate_params(params, seed, seedlen,
pcounter))
goto err;
params->h = hret;
}
pass:
if ((flags & FFC_PARAM_FLAG_VALIDATE_G) != 0 && (canonical_g == 0))
/* Return for the case where g is partially valid */
ok = FFC_PARAM_RET_STATUS_UNVERIFIABLE_G;
else
ok = FFC_PARAM_RET_STATUS_SUCCESS;
err:
if (seed != params->seed)
OPENSSL_free(seed);
OPENSSL_free(seed_tmp);
if (ctx != NULL)
BN_CTX_end(ctx);
BN_CTX_free(ctx);
BN_MONT_CTX_free(mont);
EVP_MD_CTX_free(mctx);
EVP_MD_free(md);
return ok;
}
/* Note this function is only used for verification in fips mode */
int ossl_ffc_params_FIPS186_2_gen_verify(OSSL_LIB_CTX *libctx,
FFC_PARAMS *params, int mode, int type,
size_t L, size_t N, int *res,
BN_GENCB *cb)
{
int ok = FFC_PARAM_RET_STATUS_FAILED;
unsigned char seed[SHA256_DIGEST_LENGTH];
unsigned char buf[SHA256_DIGEST_LENGTH];
BIGNUM *r0, *test, *tmp, *g = NULL, *q = NULL, *p = NULL;
BN_MONT_CTX *mont = NULL;
EVP_MD *md = NULL;
size_t qsize;
int n = 0, m = 0;
int counter = 0, pcounter = 0, use_random_seed;
int rv;
BN_CTX *ctx = NULL;
int hret = -1;
unsigned char *seed_in = params->seed;
size_t seed_len = params->seedlen;
int verify = (mode == FFC_PARAM_MODE_VERIFY);
unsigned int flags = verify ? params->flags : 0;
const char *def_name;
*res = 0;
if (params->mdname != NULL) {
md = EVP_MD_fetch(libctx, params->mdname, params->mdprops);
} else {
if (N == 0)
N = (L >= 2048 ? SHA256_DIGEST_LENGTH : SHA_DIGEST_LENGTH) * 8;
def_name = default_mdname(N);
if (def_name == NULL) {
*res = FFC_CHECK_INVALID_Q_VALUE;
goto err;
}
md = EVP_MD_fetch(libctx, def_name, params->mdprops);
}
if (md == NULL)
goto err;
if (N == 0)
N = EVP_MD_size(md) * 8;
qsize = N >> 3;
/*
* The original spec allowed L = 512 + 64*j (j = 0.. 8)
* https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-131Ar2.pdf
* says that 512 can be used for legacy verification.
*/
if (L < 512) {
*res = FFC_CHECK_BAD_LN_PAIR;
goto err;
}
if (qsize != SHA_DIGEST_LENGTH
&& qsize != SHA224_DIGEST_LENGTH
&& qsize != SHA256_DIGEST_LENGTH) {
/* invalid q size */
*res = FFC_CHECK_INVALID_Q_VALUE;
goto err;
}
L = (L + 63) / 64 * 64;
if (seed_in != NULL) {
if (seed_len < qsize) {
*res = FFC_CHECK_INVALID_SEED_SIZE;
goto err;
}
/* Only consume as much seed as is expected. */
if (seed_len > qsize)
seed_len = qsize;
memcpy(seed, seed_in, seed_len);
}
ctx = BN_CTX_new_ex(libctx);
if (ctx == NULL)
goto err;
BN_CTX_start(ctx);
r0 = BN_CTX_get(ctx);
g = BN_CTX_get(ctx);
q = BN_CTX_get(ctx);
p = BN_CTX_get(ctx);
tmp = BN_CTX_get(ctx);
test = BN_CTX_get(ctx);
if (test == NULL)
goto err;
if (!BN_lshift(test, BN_value_one(), L - 1))
goto err;
if (!verify) {
/* For generation: p & q must both be NULL or NON-NULL */
if ((params->p != NULL) != (params->q != NULL)) {
*res = FFC_CHECK_INVALID_PQ;
goto err;
}
} else {
if ((flags & FFC_PARAM_FLAG_VALIDATE_PQ) != 0) {
/* Validation of p,q requires seed and counter to be valid */
if (seed_in == NULL || params->pcounter < 0) {
*res = FFC_CHECK_MISSING_SEED_OR_COUNTER;
goto err;
}
}
if ((flags & FFC_PARAM_FLAG_VALIDATE_G) != 0) {
/* validation of g also requires g to be set */
if (params->g == NULL) {
*res = FFC_CHECK_INVALID_G;
goto err;
}
}
}
if (params->p != NULL && ((flags & FFC_PARAM_FLAG_VALIDATE_PQ) == 0)) {
/* p and q already exists so only generate g */
p = params->p;
q = params->q;
goto g_only;
/* otherwise fall thru to validate p and q */
}
use_random_seed = (seed_in == NULL);
for (;;) {
if (!generate_q_fips186_2(ctx, q, md, buf, seed, qsize,
use_random_seed, &m, res, cb))
goto err;
if (!BN_GENCB_call(cb, 2, 0))
goto err;
if (!BN_GENCB_call(cb, 3, 0))
goto err;
/* step 6 */
n = (L - 1) / 160;
counter = 4 * L - 1; /* Was 4096 */
/* Validation requires the counter to be supplied */
if (verify) {
if (params->pcounter > counter) {
*res = FFC_CHECK_INVALID_COUNTER;
goto err;
}
counter = params->pcounter;
}
rv = generate_p(ctx, md, counter, n, buf, qsize, q, p, L, cb,
&pcounter, res);
if (rv > 0)
break; /* found it */
if (rv == -1)
goto err;
/* This is what the old code did - probably not a good idea! */
use_random_seed = 1;
}
if (!BN_GENCB_call(cb, 2, 1))
goto err;
if (verify) {
if (pcounter != counter) {
*res = FFC_CHECK_COUNTER_MISMATCH;
goto err;
}
if (BN_cmp(p, params->p) != 0) {
*res = FFC_CHECK_P_MISMATCH;
goto err;
}
}
/* If validating p & q only then skip the g validation test */
if ((flags & FFC_PARAM_FLAG_VALIDATE_ALL) == FFC_PARAM_FLAG_VALIDATE_PQ)
goto pass;
g_only:
if ((mont = BN_MONT_CTX_new()) == NULL)
goto err;
if (!BN_MONT_CTX_set(mont, p, ctx))
goto err;
if (!verify) {
/* We now need to generate g */
/* set test = p - 1 */
if (!BN_sub(test, p, BN_value_one()))
goto err;
/* Set r0 = (p - 1) / q */
if (!BN_div(r0, NULL, test, q, ctx))
goto err;
if (!generate_unverifiable_g(ctx, mont, g, tmp, p, r0, test, &hret))
goto err;
} else if (((flags & FFC_PARAM_FLAG_VALIDATE_G) != 0)
&& !ossl_ffc_params_validate_unverifiable_g(ctx, mont, p, q,
params->g, tmp,
res)) {
goto err;
}
if (!BN_GENCB_call(cb, 3, 1))
goto err;
if (!verify) {
if (p != params->p) {
BN_free(params->p);
params->p = BN_dup(p);
}
if (q != params->q) {
BN_free(params->q);
params->q = BN_dup(q);
}
if (g != params->g) {
BN_free(params->g);
params->g = BN_dup(g);
}
if (params->p == NULL || params->q == NULL || params->g == NULL)
goto err;
if (!ossl_ffc_params_set_validate_params(params, seed, qsize, pcounter))
goto err;
params->h = hret;
}
pass:
if ((flags & FFC_PARAM_FLAG_VALIDATE_G) != 0)
ok = FFC_PARAM_RET_STATUS_UNVERIFIABLE_G;
else
ok = FFC_PARAM_RET_STATUS_SUCCESS;
err:
if (ctx != NULL)
BN_CTX_end(ctx);
BN_CTX_free(ctx);
BN_MONT_CTX_free(mont);
EVP_MD_free(md);
return ok;
}
int ossl_ffc_params_FIPS186_4_generate(OSSL_LIB_CTX *libctx, FFC_PARAMS *params,
int type, size_t L, size_t N,
int *res, BN_GENCB *cb)
{
return ossl_ffc_params_FIPS186_4_gen_verify(libctx, params,
FFC_PARAM_MODE_GENERATE,
type, L, N, res, cb);
}
/* This should no longer be used in FIPS mode */
int ossl_ffc_params_FIPS186_2_generate(OSSL_LIB_CTX *libctx, FFC_PARAMS *params,
int type, size_t L, size_t N,
int *res, BN_GENCB *cb)
{
return ossl_ffc_params_FIPS186_2_gen_verify(libctx, params,
FFC_PARAM_MODE_GENERATE,
type, L, N, res, cb);
}