| /* |
| * Copyright 1995-2021 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 |
| */ |
| |
| /* |
| * NB: These functions have been upgraded - the previous prototypes are in |
| * dh_depr.c as wrappers to these ones. - Geoff |
| */ |
| |
| /* |
| * DH low level APIs are deprecated for public use, but still ok for |
| * internal use. |
| * |
| * NOTE: When generating keys for key-agreement schemes - FIPS 140-2 IG 9.9 |
| * states that no additional pairwise tests are required (apart from the tests |
| * specified in SP800-56A) when generating keys. Hence DH pairwise tests are |
| * omitted here. |
| */ |
| #include "internal/deprecated.h" |
| |
| #include <stdio.h> |
| #include "internal/cryptlib.h" |
| #include <openssl/bn.h> |
| #include <openssl/sha.h> |
| #include "crypto/dh.h" |
| #include "dh_local.h" |
| |
| #ifndef FIPS_MODULE |
| static int dh_builtin_genparams(DH *ret, int prime_len, int generator, |
| BN_GENCB *cb); |
| #endif /* FIPS_MODULE */ |
| |
| int ossl_dh_generate_ffc_parameters(DH *dh, int type, int pbits, int qbits, |
| BN_GENCB *cb) |
| { |
| int ret, res; |
| |
| #ifndef FIPS_MODULE |
| if (type == DH_PARAMGEN_TYPE_FIPS_186_2) |
| ret = ossl_ffc_params_FIPS186_2_generate(dh->libctx, &dh->params, |
| FFC_PARAM_TYPE_DH, |
| pbits, qbits, &res, cb); |
| else |
| #endif |
| ret = ossl_ffc_params_FIPS186_4_generate(dh->libctx, &dh->params, |
| FFC_PARAM_TYPE_DH, |
| pbits, qbits, &res, cb); |
| if (ret > 0) |
| dh->dirty_cnt++; |
| return ret; |
| } |
| |
| int ossl_dh_get_named_group_uid_from_size(int pbits) |
| { |
| /* |
| * Just choose an approved safe prime group. |
| * The alternative to this is to generate FIPS186-4 domain parameters i.e. |
| * return dh_generate_ffc_parameters(ret, prime_len, 0, NULL, cb); |
| * As the FIPS186-4 generated params are for backwards compatibility, |
| * the safe prime group should be used as the default. |
| */ |
| int nid; |
| |
| switch (pbits) { |
| case 2048: |
| nid = NID_ffdhe2048; |
| break; |
| case 3072: |
| nid = NID_ffdhe3072; |
| break; |
| case 4096: |
| nid = NID_ffdhe4096; |
| break; |
| case 6144: |
| nid = NID_ffdhe6144; |
| break; |
| case 8192: |
| nid = NID_ffdhe8192; |
| break; |
| /* unsupported prime_len */ |
| default: |
| return NID_undef; |
| } |
| return nid; |
| } |
| |
| #ifdef FIPS_MODULE |
| |
| static int dh_gen_named_group(OSSL_LIB_CTX *libctx, DH *ret, int prime_len) |
| { |
| DH *dh; |
| int ok = 0; |
| int nid = ossl_dh_get_named_group_uid_from_size(prime_len); |
| |
| if (nid == NID_undef) |
| return 0; |
| |
| dh = ossl_dh_new_by_nid_ex(libctx, nid); |
| if (dh != NULL |
| && ossl_ffc_params_copy(&ret->params, &dh->params)) { |
| ok = 1; |
| ret->dirty_cnt++; |
| } |
| DH_free(dh); |
| return ok; |
| } |
| #endif /* FIPS_MODULE */ |
| |
| int DH_generate_parameters_ex(DH *ret, int prime_len, int generator, |
| BN_GENCB *cb) |
| { |
| #ifdef FIPS_MODULE |
| if (generator != 2) |
| return 0; |
| return dh_gen_named_group(ret->libctx, ret, prime_len); |
| #else |
| if (ret->meth->generate_params) |
| return ret->meth->generate_params(ret, prime_len, generator, cb); |
| return dh_builtin_genparams(ret, prime_len, generator, cb); |
| #endif /* FIPS_MODULE */ |
| } |
| |
| #ifndef FIPS_MODULE |
| /*- |
| * We generate DH parameters as follows |
| * find a prime p which is prime_len bits long, |
| * where q=(p-1)/2 is also prime. |
| * In the following we assume that g is not 0, 1 or p-1, since it |
| * would generate only trivial subgroups. |
| * For this case, g is a generator of the order-q subgroup if |
| * g^q mod p == 1. |
| * Or in terms of the Legendre symbol: (g/p) == 1. |
| * |
| * Having said all that, |
| * there is another special case method for the generators 2, 3 and 5. |
| * Using the quadratic reciprocity law it is possible to solve |
| * (g/p) == 1 for the special values 2, 3, 5: |
| * (2/p) == 1 if p mod 8 == 1 or 7. |
| * (3/p) == 1 if p mod 12 == 1 or 11. |
| * (5/p) == 1 if p mod 5 == 1 or 4. |
| * See for instance: https://en.wikipedia.org/wiki/Legendre_symbol |
| * |
| * Since all safe primes > 7 must satisfy p mod 12 == 11 |
| * and all safe primes > 11 must satisfy p mod 5 != 1 |
| * we can further improve the condition for g = 2, 3 and 5: |
| * for 2, p mod 24 == 23 |
| * for 3, p mod 12 == 11 |
| * for 5, p mod 60 == 59 |
| */ |
| static int dh_builtin_genparams(DH *ret, int prime_len, int generator, |
| BN_GENCB *cb) |
| { |
| BIGNUM *t1, *t2; |
| int g, ok = -1; |
| BN_CTX *ctx = NULL; |
| |
| if (prime_len > OPENSSL_DH_MAX_MODULUS_BITS) { |
| ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE); |
| return 0; |
| } |
| |
| if (prime_len < DH_MIN_MODULUS_BITS) { |
| ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL); |
| return 0; |
| } |
| |
| ctx = BN_CTX_new(); |
| if (ctx == NULL) |
| goto err; |
| BN_CTX_start(ctx); |
| t1 = BN_CTX_get(ctx); |
| t2 = BN_CTX_get(ctx); |
| if (t2 == NULL) |
| goto err; |
| |
| /* Make sure 'ret' has the necessary elements */ |
| if (ret->params.p == NULL && ((ret->params.p = BN_new()) == NULL)) |
| goto err; |
| if (ret->params.g == NULL && ((ret->params.g = BN_new()) == NULL)) |
| goto err; |
| |
| if (generator <= 1) { |
| ERR_raise(ERR_LIB_DH, DH_R_BAD_GENERATOR); |
| goto err; |
| } |
| if (generator == DH_GENERATOR_2) { |
| if (!BN_set_word(t1, 24)) |
| goto err; |
| if (!BN_set_word(t2, 23)) |
| goto err; |
| g = 2; |
| } else if (generator == DH_GENERATOR_5) { |
| if (!BN_set_word(t1, 60)) |
| goto err; |
| if (!BN_set_word(t2, 59)) |
| goto err; |
| g = 5; |
| } else { |
| /* |
| * in the general case, don't worry if 'generator' is a generator or |
| * not: since we are using safe primes, it will generate either an |
| * order-q or an order-2q group, which both is OK |
| */ |
| if (!BN_set_word(t1, 12)) |
| goto err; |
| if (!BN_set_word(t2, 11)) |
| goto err; |
| g = generator; |
| } |
| |
| if (!BN_generate_prime_ex(ret->params.p, prime_len, 1, t1, t2, cb)) |
| goto err; |
| if (!BN_GENCB_call(cb, 3, 0)) |
| goto err; |
| if (!BN_set_word(ret->params.g, g)) |
| goto err; |
| ret->dirty_cnt++; |
| ok = 1; |
| err: |
| if (ok == -1) { |
| ERR_raise(ERR_LIB_DH, ERR_R_BN_LIB); |
| ok = 0; |
| } |
| |
| BN_CTX_end(ctx); |
| BN_CTX_free(ctx); |
| return ok; |
| } |
| #endif /* FIPS_MODULE */ |
