1 /* 2 * Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the Apache License 2.0 (the "License"). You may not use 5 * this file except in compliance with the License. You can obtain a copy 6 * in the file LICENSE in the source distribution or at 7 * https://www.openssl.org/source/license.html 8 */ 9 10 /* 11 * Finite Field cryptography (FFC) is used for DSA and DH. 12 * This file contains methods for validation of FFC parameters. 13 * It calls the same functions as the generation as the code is very similar. 14 */ 15 16 #include <openssl/err.h> 17 #include <openssl/bn.h> 18 #include <openssl/dsaerr.h> 19 #include <openssl/dherr.h> 20 #include "internal/ffc.h" 21 22 /* FIPS186-4 A.2.2 Unverifiable partial validation of Generator g */ ossl_ffc_params_validate_unverifiable_g(BN_CTX * ctx,BN_MONT_CTX * mont,const BIGNUM * p,const BIGNUM * q,const BIGNUM * g,BIGNUM * tmp,int * ret)23 int ossl_ffc_params_validate_unverifiable_g(BN_CTX *ctx, BN_MONT_CTX *mont, 24 const BIGNUM *p, const BIGNUM *q, 25 const BIGNUM *g, BIGNUM *tmp, 26 int *ret) 27 { 28 /* 29 * A.2.2 Step (1) AND 30 * A.2.4 Step (2) 31 * Verify that 2 <= g <= (p - 1) 32 */ 33 if (BN_cmp(g, BN_value_one()) <= 0 || BN_cmp(g, p) >= 0) { 34 *ret |= FFC_ERROR_NOT_SUITABLE_GENERATOR; 35 return 0; 36 } 37 38 /* 39 * A.2.2 Step (2) AND 40 * A.2.4 Step (3) 41 * Check g^q mod p = 1 42 */ 43 if (!BN_mod_exp_mont(tmp, g, q, p, ctx, mont)) 44 return 0; 45 if (BN_cmp(tmp, BN_value_one()) != 0) { 46 *ret |= FFC_ERROR_NOT_SUITABLE_GENERATOR; 47 return 0; 48 } 49 return 1; 50 } 51 ossl_ffc_params_FIPS186_4_validate(OSSL_LIB_CTX * libctx,const FFC_PARAMS * params,int type,int * res,BN_GENCB * cb)52 int ossl_ffc_params_FIPS186_4_validate(OSSL_LIB_CTX *libctx, 53 const FFC_PARAMS *params, int type, 54 int *res, BN_GENCB *cb) 55 { 56 size_t L, N; 57 58 if (params == NULL || params->p == NULL || params->q == NULL) 59 return FFC_PARAM_RET_STATUS_FAILED; 60 61 /* A.1.1.3 Step (1..2) : L = len(p), N = len(q) */ 62 L = BN_num_bits(params->p); 63 N = BN_num_bits(params->q); 64 return ossl_ffc_params_FIPS186_4_gen_verify(libctx, (FFC_PARAMS *)params, 65 FFC_PARAM_MODE_VERIFY, type, 66 L, N, res, cb); 67 } 68 69 /* This may be used in FIPS mode to validate deprecated FIPS-186-2 Params */ ossl_ffc_params_FIPS186_2_validate(OSSL_LIB_CTX * libctx,const FFC_PARAMS * params,int type,int * res,BN_GENCB * cb)70 int ossl_ffc_params_FIPS186_2_validate(OSSL_LIB_CTX *libctx, 71 const FFC_PARAMS *params, int type, 72 int *res, BN_GENCB *cb) 73 { 74 size_t L, N; 75 76 if (params == NULL || params->p == NULL || params->q == NULL) { 77 *res = FFC_CHECK_INVALID_PQ; 78 return FFC_PARAM_RET_STATUS_FAILED; 79 } 80 81 /* A.1.1.3 Step (1..2) : L = len(p), N = len(q) */ 82 L = BN_num_bits(params->p); 83 N = BN_num_bits(params->q); 84 return ossl_ffc_params_FIPS186_2_gen_verify(libctx, (FFC_PARAMS *)params, 85 FFC_PARAM_MODE_VERIFY, type, 86 L, N, res, cb); 87 } 88 89 /* 90 * This does a simple check of L and N and partial g. 91 * It makes no attempt to do a full validation of p, q or g since these require 92 * extra parameters such as the digest and seed, which may not be available for 93 * this test. 94 */ ossl_ffc_params_simple_validate(OSSL_LIB_CTX * libctx,const FFC_PARAMS * params,int paramstype,int * res)95 int ossl_ffc_params_simple_validate(OSSL_LIB_CTX *libctx, const FFC_PARAMS *params, 96 int paramstype, int *res) 97 { 98 int ret; 99 int tmpres = 0; 100 FFC_PARAMS tmpparams = {0}; 101 102 if (params == NULL) 103 return 0; 104 105 if (res == NULL) 106 res = &tmpres; 107 108 if (!ossl_ffc_params_copy(&tmpparams, params)) 109 return 0; 110 111 tmpparams.flags = FFC_PARAM_FLAG_VALIDATE_G; 112 tmpparams.gindex = FFC_UNVERIFIABLE_GINDEX; 113 114 #ifndef FIPS_MODULE 115 if (params->flags & FFC_PARAM_FLAG_VALIDATE_LEGACY) 116 ret = ossl_ffc_params_FIPS186_2_validate(libctx, &tmpparams, paramstype, 117 res, NULL); 118 else 119 #endif 120 ret = ossl_ffc_params_FIPS186_4_validate(libctx, &tmpparams, paramstype, 121 res, NULL); 122 #ifndef OPENSSL_NO_DH 123 if (ret == FFC_PARAM_RET_STATUS_FAILED 124 && (*res & FFC_ERROR_NOT_SUITABLE_GENERATOR) != 0) { 125 ERR_raise(ERR_LIB_DH, DH_R_NOT_SUITABLE_GENERATOR); 126 } 127 #endif 128 129 ossl_ffc_params_cleanup(&tmpparams); 130 131 return ret != FFC_PARAM_RET_STATUS_FAILED; 132 } 133 134 /* 135 * If possible (or always in FIPS_MODULE) do full FIPS 186-4 validation. 136 * Otherwise do simple check but in addition also check the primality of the 137 * p and q. 138 */ ossl_ffc_params_full_validate(OSSL_LIB_CTX * libctx,const FFC_PARAMS * params,int paramstype,int * res)139 int ossl_ffc_params_full_validate(OSSL_LIB_CTX *libctx, const FFC_PARAMS *params, 140 int paramstype, int *res) 141 { 142 int tmpres = 0; 143 144 if (params == NULL) 145 return 0; 146 147 if (res == NULL) 148 res = &tmpres; 149 150 #ifdef FIPS_MODULE 151 return ossl_ffc_params_FIPS186_4_validate(libctx, params, paramstype, 152 res, NULL); 153 #else 154 if (params->seed != NULL) { 155 if (params->flags & FFC_PARAM_FLAG_VALIDATE_LEGACY) 156 return ossl_ffc_params_FIPS186_2_validate(libctx, params, paramstype, 157 res, NULL); 158 else 159 return ossl_ffc_params_FIPS186_4_validate(libctx, params, paramstype, 160 res, NULL); 161 } else { 162 int ret = 0; 163 164 ret = ossl_ffc_params_simple_validate(libctx, params, paramstype, res); 165 if (ret) { 166 BN_CTX *ctx; 167 168 if ((ctx = BN_CTX_new_ex(libctx)) == NULL) 169 return 0; 170 if (BN_check_prime(params->q, ctx, NULL) != 1) { 171 # ifndef OPENSSL_NO_DSA 172 ERR_raise(ERR_LIB_DSA, DSA_R_Q_NOT_PRIME); 173 # endif 174 ret = 0; 175 } 176 if (ret && BN_check_prime(params->p, ctx, NULL) != 1) { 177 # ifndef OPENSSL_NO_DSA 178 ERR_raise(ERR_LIB_DSA, DSA_R_P_NOT_PRIME); 179 # endif 180 ret = 0; 181 } 182 BN_CTX_free(ctx); 183 } 184 return ret; 185 } 186 #endif 187 } 188