| 1 | /*
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| 2 | * Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.
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| 3 | *
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| 4 | * Licensed under the Apache License 2.0 (the "License"). You may not use
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| 5 | * this file except in compliance with the License. You can obtain a copy
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| 6 | * in the file LICENSE in the source distribution or at
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| 7 | * https://www.openssl.org/source/license.html
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| 8 | */
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| 9 |
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| 10 | /*
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| 11 | * DH low level APIs are deprecated for public use, but still ok for
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| 12 | * internal use.
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| 13 | */
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| 14 | #include "internal/deprecated.h"
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| 15 |
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| 16 | #include <stdio.h>
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| 17 | #include "internal/cryptlib.h"
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| 18 | #include <openssl/bn.h>
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| 19 | #include "dh_local.h"
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| 20 | #include "crypto/dh.h"
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| 21 |
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| 22 | /*-
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| 23 | * Check that p and g are suitable enough
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| 24 | *
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| 25 | * p is odd
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| 26 | * 1 < g < p - 1
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| 27 | */
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| 28 | int DH_check_params_ex(const DH *dh)
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| 29 | {
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| 30 | int errflags = 0;
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| 31 |
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| 32 | if (!DH_check_params(dh, &errflags))
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| 33 | return 0;
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| 34 |
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| 35 | if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
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| 36 | ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_PRIME);
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| 37 | if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
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| 38 | ERR_raise(ERR_LIB_DH, DH_R_NOT_SUITABLE_GENERATOR);
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| 39 | if ((errflags & DH_MODULUS_TOO_SMALL) != 0)
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| 40 | ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
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| 41 | if ((errflags & DH_MODULUS_TOO_LARGE) != 0)
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| 42 | ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
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| 43 |
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| 44 | return errflags == 0;
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| 45 | }
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| 46 |
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| 47 | #ifdef FIPS_MODULE
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| 48 | int DH_check_params(const DH *dh, int *ret)
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| 49 | {
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| 50 | int nid;
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| 51 |
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| 52 | *ret = 0;
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| 53 | /*
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| 54 | * SP800-56A R3 Section 5.5.2 Assurances of Domain Parameter Validity
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| 55 | * (1a) The domain parameters correspond to any approved safe prime group.
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| 56 | */
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| 57 | nid = DH_get_nid((DH *)dh);
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| 58 | if (nid != NID_undef)
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| 59 | return 1;
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| 60 | /*
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| 61 | * OR
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| 62 | * (2b) FFC domain params conform to FIPS-186-4 explicit domain param
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| 63 | * validity tests.
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| 64 | */
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| 65 | return ossl_ffc_params_FIPS186_4_validate(dh->libctx, &dh->params,
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| 66 | FFC_PARAM_TYPE_DH, ret, NULL);
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| 67 | }
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| 68 | #else
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| 69 | int DH_check_params(const DH *dh, int *ret)
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| 70 | {
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| 71 | int ok = 0;
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| 72 | BIGNUM *tmp = NULL;
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| 73 | BN_CTX *ctx = NULL;
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| 74 |
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| 75 | *ret = 0;
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| 76 | ctx = BN_CTX_new();
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| 77 | if (ctx == NULL)
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| 78 | goto err;
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| 79 | BN_CTX_start(ctx);
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| 80 | tmp = BN_CTX_get(ctx);
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| 81 | if (tmp == NULL)
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| 82 | goto err;
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| 83 |
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| 84 | if (!BN_is_odd(dh->params.p))
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| 85 | *ret |= DH_CHECK_P_NOT_PRIME;
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| 86 | if (BN_is_negative(dh->params.g)
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| 87 | || BN_is_zero(dh->params.g)
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| 88 | || BN_is_one(dh->params.g))
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| 89 | *ret |= DH_NOT_SUITABLE_GENERATOR;
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| 90 | if (BN_copy(tmp, dh->params.p) == NULL || !BN_sub_word(tmp, 1))
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| 91 | goto err;
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| 92 | if (BN_cmp(dh->params.g, tmp) >= 0)
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| 93 | *ret |= DH_NOT_SUITABLE_GENERATOR;
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| 94 | if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS)
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| 95 | *ret |= DH_MODULUS_TOO_SMALL;
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| 96 | if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS)
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| 97 | *ret |= DH_MODULUS_TOO_LARGE;
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| 98 |
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| 99 | ok = 1;
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| 100 | err:
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| 101 | BN_CTX_end(ctx);
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| 102 | BN_CTX_free(ctx);
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| 103 | return ok;
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| 104 | }
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| 105 | #endif /* FIPS_MODULE */
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| 106 |
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| 107 | /*-
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| 108 | * Check that p is a safe prime and
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| 109 | * g is a suitable generator.
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| 110 | */
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| 111 | int DH_check_ex(const DH *dh)
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| 112 | {
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| 113 | int errflags = 0;
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| 114 |
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| 115 | if (!DH_check(dh, &errflags))
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| 116 | return 0;
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| 117 |
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| 118 | if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
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| 119 | ERR_raise(ERR_LIB_DH, DH_R_NOT_SUITABLE_GENERATOR);
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| 120 | if ((errflags & DH_CHECK_Q_NOT_PRIME) != 0)
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| 121 | ERR_raise(ERR_LIB_DH, DH_R_CHECK_Q_NOT_PRIME);
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| 122 | if ((errflags & DH_CHECK_INVALID_Q_VALUE) != 0)
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| 123 | ERR_raise(ERR_LIB_DH, DH_R_CHECK_INVALID_Q_VALUE);
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| 124 | if ((errflags & DH_CHECK_INVALID_J_VALUE) != 0)
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| 125 | ERR_raise(ERR_LIB_DH, DH_R_CHECK_INVALID_J_VALUE);
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| 126 | if ((errflags & DH_UNABLE_TO_CHECK_GENERATOR) != 0)
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| 127 | ERR_raise(ERR_LIB_DH, DH_R_UNABLE_TO_CHECK_GENERATOR);
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| 128 | if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
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| 129 | ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_PRIME);
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| 130 | if ((errflags & DH_CHECK_P_NOT_SAFE_PRIME) != 0)
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| 131 | ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_SAFE_PRIME);
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| 132 | if ((errflags & DH_MODULUS_TOO_SMALL) != 0)
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| 133 | ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
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| 134 | if ((errflags & DH_MODULUS_TOO_LARGE) != 0)
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| 135 | ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
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| 136 |
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| 137 | return errflags == 0;
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| 138 | }
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| 139 |
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| 140 | /* Note: according to documentation - this only checks the params */
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| 141 | int DH_check(const DH *dh, int *ret)
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| 142 | {
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| 143 | #ifdef FIPS_MODULE
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| 144 | return DH_check_params(dh, ret);
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| 145 | #else
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| 146 | int ok = 0, r;
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| 147 | BN_CTX *ctx = NULL;
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| 148 | BIGNUM *t1 = NULL, *t2 = NULL;
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| 149 | int nid = DH_get_nid((DH *)dh);
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| 150 |
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| 151 | *ret = 0;
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| 152 | if (nid != NID_undef)
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| 153 | return 1;
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| 154 |
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| 155 | if (!DH_check_params(dh, ret))
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| 156 | return 0;
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| 157 |
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| 158 | ctx = BN_CTX_new();
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| 159 | if (ctx == NULL)
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| 160 | goto err;
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| 161 | BN_CTX_start(ctx);
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| 162 | t1 = BN_CTX_get(ctx);
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| 163 | t2 = BN_CTX_get(ctx);
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| 164 | if (t2 == NULL)
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| 165 | goto err;
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| 166 |
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| 167 | if (dh->params.q != NULL) {
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| 168 | if (BN_cmp(dh->params.g, BN_value_one()) <= 0)
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| 169 | *ret |= DH_NOT_SUITABLE_GENERATOR;
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| 170 | else if (BN_cmp(dh->params.g, dh->params.p) >= 0)
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| 171 | *ret |= DH_NOT_SUITABLE_GENERATOR;
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| 172 | else {
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| 173 | /* Check g^q == 1 mod p */
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| 174 | if (!BN_mod_exp(t1, dh->params.g, dh->params.q, dh->params.p, ctx))
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| 175 | goto err;
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| 176 | if (!BN_is_one(t1))
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| 177 | *ret |= DH_NOT_SUITABLE_GENERATOR;
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| 178 | }
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| 179 | r = BN_check_prime(dh->params.q, ctx, NULL);
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| 180 | if (r < 0)
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| 181 | goto err;
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| 182 | if (!r)
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| 183 | *ret |= DH_CHECK_Q_NOT_PRIME;
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| 184 | /* Check p == 1 mod q i.e. q divides p - 1 */
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| 185 | if (!BN_div(t1, t2, dh->params.p, dh->params.q, ctx))
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| 186 | goto err;
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| 187 | if (!BN_is_one(t2))
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| 188 | *ret |= DH_CHECK_INVALID_Q_VALUE;
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| 189 | if (dh->params.j != NULL
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| 190 | && BN_cmp(dh->params.j, t1))
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| 191 | *ret |= DH_CHECK_INVALID_J_VALUE;
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| 192 | }
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| 193 |
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| 194 | r = BN_check_prime(dh->params.p, ctx, NULL);
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| 195 | if (r < 0)
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| 196 | goto err;
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| 197 | if (!r)
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| 198 | *ret |= DH_CHECK_P_NOT_PRIME;
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| 199 | else if (dh->params.q == NULL) {
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| 200 | if (!BN_rshift1(t1, dh->params.p))
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| 201 | goto err;
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| 202 | r = BN_check_prime(t1, ctx, NULL);
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| 203 | if (r < 0)
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| 204 | goto err;
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| 205 | if (!r)
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| 206 | *ret |= DH_CHECK_P_NOT_SAFE_PRIME;
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| 207 | }
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| 208 | ok = 1;
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| 209 | err:
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| 210 | BN_CTX_end(ctx);
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| 211 | BN_CTX_free(ctx);
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| 212 | return ok;
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| 213 | #endif /* FIPS_MODULE */
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| 214 | }
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| 215 |
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| 216 | int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key)
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| 217 | {
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| 218 | int errflags = 0;
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| 219 |
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| 220 | if (!DH_check_pub_key(dh, pub_key, &errflags))
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| 221 | return 0;
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| 222 |
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| 223 | if ((errflags & DH_CHECK_PUBKEY_TOO_SMALL) != 0)
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| 224 | ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_TOO_SMALL);
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| 225 | if ((errflags & DH_CHECK_PUBKEY_TOO_LARGE) != 0)
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| 226 | ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_TOO_LARGE);
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| 227 | if ((errflags & DH_CHECK_PUBKEY_INVALID) != 0)
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| 228 | ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_INVALID);
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| 229 |
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| 230 | return errflags == 0;
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| 231 | }
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| 232 |
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| 233 | /*
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| 234 | * See SP800-56Ar3 Section 5.6.2.3.1 : FFC Full public key validation.
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| 235 | */
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| 236 | int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
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| 237 | {
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| 238 | return ossl_ffc_validate_public_key(&dh->params, pub_key, ret);
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| 239 | }
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| 240 |
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| 241 | /*
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| 242 | * See SP800-56Ar3 Section 5.6.2.3.1 : FFC Partial public key validation.
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| 243 | * To only be used with ephemeral FFC public keys generated using the approved
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| 244 | * safe-prime groups.
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| 245 | */
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| 246 | int ossl_dh_check_pub_key_partial(const DH *dh, const BIGNUM *pub_key, int *ret)
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| 247 | {
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| 248 | return ossl_ffc_validate_public_key_partial(&dh->params, pub_key, ret);
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| 249 | }
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| 250 |
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| 251 | int ossl_dh_check_priv_key(const DH *dh, const BIGNUM *priv_key, int *ret)
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| 252 | {
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| 253 | int ok = 0;
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| 254 | BIGNUM *two_powN = NULL, *upper;
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| 255 |
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| 256 | *ret = 0;
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| 257 | two_powN = BN_new();
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| 258 | if (two_powN == NULL)
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| 259 | return 0;
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| 260 | if (dh->params.q == NULL)
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| 261 | goto err;
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| 262 | upper = dh->params.q;
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| 263 |
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| 264 | /* Is it from an approved Safe prime group ?*/
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| 265 | if (DH_get_nid((DH *)dh) != NID_undef && dh->length != 0) {
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| 266 | if (!BN_lshift(two_powN, BN_value_one(), dh->length))
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| 267 | goto err;
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| 268 | if (BN_cmp(two_powN, dh->params.q) < 0)
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| 269 | upper = two_powN;
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| 270 | }
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| 271 | if (!ossl_ffc_validate_private_key(upper, priv_key, ret))
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| 272 | goto err;
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| 273 |
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| 274 | ok = 1;
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| 275 | err:
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| 276 | BN_free(two_powN);
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| 277 | return ok;
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| 278 | }
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| 279 |
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| 280 | /*
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| 281 | * FFC pairwise check from SP800-56A R3.
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| 282 | * Section 5.6.2.1.4 Owner Assurance of Pair-wise Consistency
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| 283 | */
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| 284 | int ossl_dh_check_pairwise(const DH *dh)
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| 285 | {
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| 286 | int ret = 0;
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| 287 | BN_CTX *ctx = NULL;
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| 288 | BIGNUM *pub_key = NULL;
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| 289 |
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| 290 | if (dh->params.p == NULL
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| 291 | || dh->params.g == NULL
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| 292 | || dh->priv_key == NULL
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| 293 | || dh->pub_key == NULL)
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| 294 | return 0;
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| 295 |
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| 296 | ctx = BN_CTX_new_ex(dh->libctx);
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| 297 | if (ctx == NULL)
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| 298 | goto err;
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| 299 | pub_key = BN_new();
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| 300 | if (pub_key == NULL)
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| 301 | goto err;
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| 302 |
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| 303 | /* recalculate the public key = (g ^ priv) mod p */
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| 304 | if (!ossl_dh_generate_public_key(ctx, dh, dh->priv_key, pub_key))
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| 305 | goto err;
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| 306 | /* check it matches the existing pubic_key */
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| 307 | ret = BN_cmp(pub_key, dh->pub_key) == 0;
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| 308 | err:
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| 309 | BN_free(pub_key);
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| 310 | BN_CTX_free(ctx);
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| 311 | return ret;
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| 312 | }
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