X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=libtomcrypt%2Fsrc%2Fpk%2Fdsa%2Fdsa_generate_pqg.c;fp=libtomcrypt%2Fsrc%2Fpk%2Fdsa%2Fdsa_generate_pqg.c;h=8c5f55829c133d00e4fa8e0b2bb9254b19b4bd45;hb=66bc25938679f1d6a1d1200f329093d82a5e99b4;hp=0000000000000000000000000000000000000000;hpb=a52ee0733f420ca20224049260d6fc5cf7d8f621;p=zpackage diff --git a/libtomcrypt/src/pk/dsa/dsa_generate_pqg.c b/libtomcrypt/src/pk/dsa/dsa_generate_pqg.c new file mode 100644 index 0000000..8c5f558 --- /dev/null +++ b/libtomcrypt/src/pk/dsa/dsa_generate_pqg.c @@ -0,0 +1,244 @@ +/* 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 = 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: $Format:%ai$ */