Mercurial > dropbear
view libtomcrypt/src/pk/dsa/dsa_generate_pqg.c @ 1833:870f6e386a0b
Partial strings from strtoul should return error
author | Matt Johnston <matt@codeconstruct.com.au> |
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date | Tue, 12 Oct 2021 23:31:09 +0800 |
parents | e9dba7abd939 |
children |
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis * * LibTomCrypt is a library that provides various cryptographic * algorithms in a highly modular and flexible manner. * * The library is free for all purposes without any express * guarantee it works. */ #include "tomcrypt.h" /** @file dsa_generate_pqg.c DSA implementation - generate DSA parameters p, q & g */ #ifdef LTC_MDSA /** Create DSA parameters (INTERNAL ONLY, not part of public API) @param prng An active PRNG state @param wprng The index of the PRNG desired @param group_size Size of the multiplicative group (octets) @param modulus_size Size of the modulus (octets) @param p [out] bignum where generated 'p' is stored (must be initialized by caller) @param q [out] bignum where generated 'q' is stored (must be initialized by caller) @param g [out] bignum where generated 'g' is stored (must be initialized by caller) @return CRYPT_OK if successful, upon error this function will free all allocated memory */ static int _dsa_make_params(prng_state *prng, int wprng, int group_size, int modulus_size, void *p, void *q, void *g) { unsigned long L, N, n, outbytes, seedbytes, counter, j, i; int err, res, mr_tests_q, mr_tests_p, found_p, found_q, hash; unsigned char *wbuf, *sbuf, digest[MAXBLOCKSIZE]; void *t2L1, *t2N1, *t2q, *t2seedlen, *U, *W, *X, *c, *h, *e, *seedinc; /* check size */ if (group_size >= LTC_MDSA_MAX_GROUP || group_size < 1 || group_size >= modulus_size) { return CRYPT_INVALID_ARG; } /* FIPS-186-4 A.1.1.2 Generation of the Probable Primes p and q Using an Approved Hash Function * * L = The desired length of the prime p (in bits e.g. L = 1024) * N = The desired length of the prime q (in bits e.g. N = 160) * seedlen = The desired bit length of the domain parameter seed; seedlen shallbe equal to or greater than N * outlen = The bit length of Hash function * * 1. Check that the (L, N) * 2. If (seedlen <N), then return INVALID. * 3. n = ceil(L / outlen) - 1 * 4. b = L- 1 - (n * outlen) * 5. domain_parameter_seed = an arbitrary sequence of seedlen bits * 6. U = Hash (domain_parameter_seed) mod 2^(N-1) * 7. q = 2^(N-1) + U + 1 - (U mod 2) * 8. Test whether or not q is prime as specified in Appendix C.3 * 9. If qis not a prime, then go to step 5. * 10. offset = 1 * 11. For counter = 0 to (4L- 1) do { * For j=0 to n do { * Vj = Hash ((domain_parameter_seed+ offset + j) mod 2^seedlen * } * W = V0 + (V1 *2^outlen) + ... + (Vn-1 * 2^((n-1) * outlen)) + ((Vn mod 2^b) * 2^(n * outlen)) * X = W + 2^(L-1) Comment: 0 <= W < 2^(L-1); hence 2^(L-1) <= X < 2^L * c = X mod 2*q * p = X - (c - 1) Comment: p ~ 1 (mod 2*q) * If (p >= 2^(L-1)) { * Test whether or not p is prime as specified in Appendix C.3. * If p is determined to be prime, then return VALID and the values of p, qand (optionally) the values of domain_parameter_seed and counter * } * offset = offset + n + 1 Comment: Increment offset * } */ seedbytes = group_size; L = (unsigned long)modulus_size * 8; N = (unsigned long)group_size * 8; /* XXX-TODO no Lucas test */ #ifdef LTC_MPI_HAS_LUCAS_TEST /* M-R tests (when followed by one Lucas test) according FIPS-186-4 - Appendix C.3 - table C.1 */ mr_tests_p = (L <= 2048) ? 3 : 2; if (N <= 160) { mr_tests_q = 19; } else if (N <= 224) { mr_tests_q = 24; } else { mr_tests_q = 27; } #else /* M-R tests (without Lucas test) according FIPS-186-4 - Appendix C.3 - table C.1 */ if (L <= 1024) { mr_tests_p = 40; } else if (L <= 2048) { mr_tests_p = 56; } else { mr_tests_p = 64; } if (N <= 160) { mr_tests_q = 40; } else if (N <= 224) { mr_tests_q = 56; } else { mr_tests_q = 64; } #endif if (N <= 256) { hash = register_hash(&sha256_desc); } else if (N <= 384) { hash = register_hash(&sha384_desc); } else if (N <= 512) { hash = register_hash(&sha512_desc); } else { return CRYPT_INVALID_ARG; /* group_size too big */ } if ((err = hash_is_valid(hash)) != CRYPT_OK) { return err; } outbytes = hash_descriptor[hash].hashsize; n = ((L + outbytes*8 - 1) / (outbytes*8)) - 1; if ((wbuf = XMALLOC((n+1)*outbytes)) == NULL) { err = CRYPT_MEM; goto cleanup3; } if ((sbuf = XMALLOC(seedbytes)) == NULL) { err = CRYPT_MEM; goto cleanup2; } err = mp_init_multi(&t2L1, &t2N1, &t2q, &t2seedlen, &U, &W, &X, &c, &h, &e, &seedinc, NULL); if (err != CRYPT_OK) { goto cleanup1; } if ((err = mp_2expt(t2L1, L-1)) != CRYPT_OK) { goto cleanup; } /* t2L1 = 2^(L-1) */ if ((err = mp_2expt(t2N1, N-1)) != CRYPT_OK) { goto cleanup; } /* t2N1 = 2^(N-1) */ if ((err = mp_2expt(t2seedlen, seedbytes*8)) != CRYPT_OK) { goto cleanup; } /* t2seedlen = 2^seedlen */ for(found_p=0; !found_p;) { /* q */ for(found_q=0; !found_q;) { if (prng_descriptor[wprng].read(sbuf, seedbytes, prng) != seedbytes) { err = CRYPT_ERROR_READPRNG; goto cleanup; } i = outbytes; if ((err = hash_memory(hash, sbuf, seedbytes, digest, &i)) != CRYPT_OK) { goto cleanup; } if ((err = mp_read_unsigned_bin(U, digest, outbytes)) != CRYPT_OK) { goto cleanup; } if ((err = mp_mod(U, t2N1, U)) != CRYPT_OK) { goto cleanup; } if ((err = mp_add(t2N1, U, q)) != CRYPT_OK) { goto cleanup; } if (!mp_isodd(q)) mp_add_d(q, 1, q); if ((err = mp_prime_is_prime(q, mr_tests_q, &res)) != CRYPT_OK) { goto cleanup; } if (res == LTC_MP_YES) found_q = 1; } /* p */ if ((err = mp_read_unsigned_bin(seedinc, sbuf, seedbytes)) != CRYPT_OK) { goto cleanup; } if ((err = mp_add(q, q, t2q)) != CRYPT_OK) { goto cleanup; } for(counter=0; counter < 4*L && !found_p; counter++) { for(j=0; j<=n; j++) { if ((err = mp_add_d(seedinc, 1, seedinc)) != CRYPT_OK) { goto cleanup; } if ((err = mp_mod(seedinc, t2seedlen, seedinc)) != CRYPT_OK) { goto cleanup; } /* seedinc = (seedinc+1) % 2^seed_bitlen */ if ((i = mp_unsigned_bin_size(seedinc)) > seedbytes) { err = CRYPT_INVALID_ARG; goto cleanup; } zeromem(sbuf, seedbytes); if ((err = mp_to_unsigned_bin(seedinc, sbuf + seedbytes-i)) != CRYPT_OK) { goto cleanup; } i = outbytes; err = hash_memory(hash, sbuf, seedbytes, wbuf+(n-j)*outbytes, &i); if (err != CRYPT_OK) { goto cleanup; } } if ((err = mp_read_unsigned_bin(W, wbuf, (n+1)*outbytes)) != CRYPT_OK) { goto cleanup; } if ((err = mp_mod(W, t2L1, W)) != CRYPT_OK) { goto cleanup; } if ((err = mp_add(W, t2L1, X)) != CRYPT_OK) { goto cleanup; } if ((err = mp_mod(X, t2q, c)) != CRYPT_OK) { goto cleanup; } if ((err = mp_sub_d(c, 1, p)) != CRYPT_OK) { goto cleanup; } if ((err = mp_sub(X, p, p)) != CRYPT_OK) { goto cleanup; } if (mp_cmp(p, t2L1) != LTC_MP_LT) { /* p >= 2^(L-1) */ if ((err = mp_prime_is_prime(p, mr_tests_p, &res)) != CRYPT_OK) { goto cleanup; } if (res == LTC_MP_YES) { found_p = 1; } } } } /* FIPS-186-4 A.2.1 Unverifiable Generation of the Generator g * 1. e = (p - 1)/q * 2. h = any integer satisfying: 1 < h < (p - 1) * h could be obtained from a random number generator or from a counter that changes after each use * 3. g = h^e mod p * 4. if (g == 1), then go to step 2. * */ if ((err = mp_sub_d(p, 1, e)) != CRYPT_OK) { goto cleanup; } if ((err = mp_div(e, q, e, c)) != CRYPT_OK) { goto cleanup; } /* e = (p - 1)/q */ i = mp_count_bits(p); do { do { if ((err = rand_bn_bits(h, i, prng, wprng)) != CRYPT_OK) { goto cleanup; } } while (mp_cmp(h, p) != LTC_MP_LT || mp_cmp_d(h, 2) != LTC_MP_GT); if ((err = mp_sub_d(h, 1, h)) != CRYPT_OK) { goto cleanup; } /* h is randon and 1 < h < (p-1) */ if ((err = mp_exptmod(h, e, p, g)) != CRYPT_OK) { goto cleanup; } } while (mp_cmp_d(g, 1) == LTC_MP_EQ); err = CRYPT_OK; cleanup: mp_clear_multi(t2L1, t2N1, t2q, t2seedlen, U, W, X, c, h, e, seedinc, NULL); cleanup1: XFREE(sbuf); cleanup2: XFREE(wbuf); cleanup3: return err; } /** Generate DSA parameters p, q & g @param prng An active PRNG state @param wprng The index of the PRNG desired @param group_size Size of the multiplicative group (octets) @param modulus_size Size of the modulus (octets) @param key [out] Where to store the created key @return CRYPT_OK if successful. */ int dsa_generate_pqg(prng_state *prng, int wprng, int group_size, int modulus_size, dsa_key *key) { int err; LTC_ARGCHK(key != NULL); LTC_ARGCHK(ltc_mp.name != NULL); /* init mp_ints */ if ((err = mp_init_multi(&key->p, &key->g, &key->q, &key->x, &key->y, NULL)) != CRYPT_OK) { return err; } /* generate params */ err = _dsa_make_params(prng, wprng, group_size, modulus_size, key->p, key->q, key->g); if (err != CRYPT_OK) { goto cleanup; } key->qord = group_size; return CRYPT_OK; cleanup: dsa_free(key); return err; } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */