1/*-
2 * Copyright 2022 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 * Example showing how to validate DSA parameters.
12 *
13 * Proper FIPS 186-4 DSA (FFC) parameter validation requires that all
14 * the parameters used during parameter generation are supplied
15 * when doing the validation. Unfortunately saving DSA parameters as
16 * a PEM or DER file does not write out all required fields. Because
17 * of this the default provider normally only does a partial
18 * validation. The FIPS provider will however try to do a full
19 * validation. To force the default provider to use full
20 * validation the 'seed' that is output during generation must be
21 * added to the key. See doc/man7/EVP_PKEY-FFC for more information.
22 */
23
24#include <openssl/evp.h>
25#include <openssl/core_names.h>
26#include <openssl/pem.h>
27#include "dsa.inc"
28
29/* The following values were output from the EVP_PKEY_DSA_paramgen demo */
30static const char dsapem[] =
31    "-----BEGIN DSA PARAMETERS-----\n"
32    "MIICLAKCAQEA1pobSR1FJ3+Tvi0J6Tk1PSV2owZey1Nuo847hGw/59VCS6RPQEqr\n"
33    "vp5fhbvBjupBeVGA/AMH6rI4i4h6jlhurrqH1CqUHVcDhJzxV668bMLiP3mIxg5o\n"
34    "9Yq8x6BnSOtH5Je0tpeE0/fEvvLjCwBUbwnwWxzjANcvDUEt9XYeRrtB2v52fr56\n"
35    "hVYz3wMMNog4CEDOLTvx7/84eVPuUeWDRQFH1EaHMdulP34KBcatEEpEZapkepng\n"
36    "nohm9sFSPQhq2utpkH7pNXdG0EILBtRDCvUpF5720a48LYofdggh2VEZfgElAGFk\n"
37    "dW/CkvyBDmGIzil5aTz4MMsdudaVYgzt6wIhAPsSGC42Qa+X0AFGvonb5nmfUVm/\n"
38    "8aC+tHk7Nb2AYLHXAoIBADx5C0H1+QHsmGKvuOaY+WKUt7aWUrEivD1zBMJAQ6bL\n"
39    "Wv9lbCq1CFHvVzojeOVpn872NqDEpkx4HTpvqhxWL5CkbN/HaGItsQzkD59AQg3v\n"
40    "4YsLlkesq9Jq6x/aWetJXWO36fszFv1gpD3NY3wliBvMYHx62jfc5suh9D3ZZvu7\n"
41    "PLGH4X4kcfzK/R2b0oVbEBjVTe5GMRYZRqnvfSW2f2fA7BzI1OL83UxDDe58cL2M\n"
42    "GcAoUYXOBAfZ37qLMm2juf+o5gCrT4CXfRPu6kbapt7V/YIc1nsNgeAOKKoFBHBQ\n"
43    "gc5u5G6G/j79FVoSDq9DYwTJcHPsU+eHj1uWHso1AjQ=\n"
44    "-----END DSA PARAMETERS-----\n";
45
46static const char hexseed[] =
47    "cba30ccd905aa7675a0b81769704bf3c"
48    "ccf2ca1892b2eaf6b9e2b38d9bf6affc"
49    "42ada55986d8a1772b442770954d0b65";
50const int gindex = 42;
51const int pcounter = 363;
52static const char digest[] = "SHA384";
53
54/*
55 * Create a new dsa param key that is the combination of an existing param key
56 * plus extra parameters.
57 */
58EVP_PKEY_CTX *create_merged_key(EVP_PKEY *dsaparams, const OSSL_PARAM *newparams,
59                                OSSL_LIB_CTX *libctx, const char *propq)
60{
61    EVP_PKEY_CTX *out = NULL;
62    EVP_PKEY_CTX *ctx = NULL;
63    EVP_PKEY *pkey = NULL;
64    OSSL_PARAM *mergedparams = NULL;
65    OSSL_PARAM *loadedparams = NULL;
66
67    /* Specify EVP_PKEY_KEY_PUBLIC here if you have a public key */
68    if (EVP_PKEY_todata(dsaparams, EVP_PKEY_KEY_PARAMETERS, &loadedparams) <= 0) {
69        fprintf(stderr, "EVP_PKEY_todata() failed\n");
70        goto cleanup;
71    }
72    mergedparams = OSSL_PARAM_merge(loadedparams, newparams);
73    if (mergedparams == NULL) {
74        fprintf(stderr, "OSSL_PARAM_merge() failed\n");
75        goto cleanup;
76    }
77
78    ctx = EVP_PKEY_CTX_new_from_name(libctx, "DSA", propq);
79    if (ctx == NULL) {
80        fprintf(stderr, "EVP_PKEY_CTX_new_from_name() failed\n");
81        goto cleanup;
82    }
83    if (EVP_PKEY_fromdata_init(ctx) <= 0
84            || EVP_PKEY_fromdata(ctx, &pkey,
85                                 EVP_PKEY_KEY_PARAMETERS, mergedparams) <= 0) {
86        fprintf(stderr, "EVP_PKEY_fromdata() failed\n");
87        goto cleanup;
88    }
89    out = EVP_PKEY_CTX_new_from_pkey(libctx, pkey, propq);
90    if (out == NULL) {
91        fprintf(stderr, "EVP_PKEY_CTX_new_from_pkey() failed\n");
92        goto cleanup;
93    }
94
95cleanup:
96    EVP_PKEY_free(pkey);
97    OSSL_PARAM_free(loadedparams);
98    OSSL_PARAM_free(mergedparams);
99    EVP_PKEY_CTX_free(ctx);
100    return out;
101}
102
103int main(int argc, char **argv)
104{
105    int rv = EXIT_FAILURE;
106    OSSL_LIB_CTX *libctx = NULL;
107    const char *propq = NULL;
108    EVP_PKEY *dsaparamskey = NULL;
109    EVP_PKEY_CTX *ctx = NULL;
110    EVP_PKEY_CTX *ctx1 = NULL;
111    EVP_PKEY_CTX *ctx2 = NULL;
112    BIO *in = NULL;
113    OSSL_PARAM params[6];
114    unsigned char seed[64];
115    size_t seedlen;
116
117    if (!OPENSSL_hexstr2buf_ex(seed, sizeof(seed), &seedlen, hexseed, '\0'))
118        goto cleanup;
119    /*
120     * This example loads the PEM data from a memory buffer
121     * Use BIO_new_fp() to load a PEM file instead
122     */
123    in = BIO_new_mem_buf(dsapem, strlen(dsapem));
124    if (in == NULL) {
125        fprintf(stderr, "BIO_new_mem_buf() failed\n");
126        goto cleanup;
127    }
128
129    /* Load DSA params from pem data */
130    dsaparamskey = PEM_read_bio_Parameters_ex(in, NULL, libctx, propq);
131    if (dsaparamskey == NULL) {
132        fprintf(stderr, "Failed to load dsa params\n");
133        goto cleanup;
134    }
135
136    ctx = EVP_PKEY_CTX_new_from_pkey(libctx, dsaparamskey, propq);
137    if (ctx == NULL) {
138        fprintf(stderr, "EVP_PKEY_CTX_new_from_pkey() failed\n");
139        goto cleanup;
140    }
141    /*
142     * When using the default provider this only does a partial check to
143     * make sure that the values of p, q and g are ok.
144     * This will fail however if the FIPS provider is used since it does
145     * a proper FIPS 186-4 key validation which requires extra parameters
146     */
147    if (EVP_PKEY_param_check(ctx) <= 0) {
148        fprintf(stderr, "Simple EVP_PKEY_param_check() failed \n");
149        goto cleanup;
150    }
151
152    /*
153     * Setup parameters that we want to add.
154     * For illustration purposes it deliberately omits a required parameter.
155     */
156    params[0] = OSSL_PARAM_construct_utf8_string(OSSL_PKEY_PARAM_FFC_TYPE,
157                                                "fips186_4", 0);
158    /* Force it to do a proper validation by setting the seed */
159    params[1] = OSSL_PARAM_construct_octet_string(OSSL_PKEY_PARAM_FFC_SEED,
160                                                  (void *)seed, seedlen);
161    params[2] = OSSL_PARAM_construct_int(OSSL_PKEY_PARAM_FFC_GINDEX, (int *)&gindex);
162    params[3] = OSSL_PARAM_construct_int(OSSL_PKEY_PARAM_FFC_PCOUNTER, (int *)&pcounter);
163    params[4] = OSSL_PARAM_construct_end();
164
165    /* generate a new key that is the combination of the existing key and the new params */
166    ctx1 = create_merged_key(dsaparamskey, params, libctx, propq);
167    if (ctx1 == NULL)
168        goto cleanup;
169    /* This will fail since not all the parameters used for key generation are added */
170    if (EVP_PKEY_param_check(ctx1) > 0) {
171        fprintf(stderr, "EVP_PKEY_param_check() should fail\n");
172        goto cleanup;
173    }
174
175    /*
176     * Add the missing parameters onto the end of the existing list of params
177     * If the default was used for the generation then this parameter is not
178     * needed
179     */
180    params[4] = OSSL_PARAM_construct_utf8_string(OSSL_PKEY_PARAM_FFC_DIGEST,
181                                                 (char *)digest, 0);
182    params[5] = OSSL_PARAM_construct_end();
183    ctx2 = create_merged_key(dsaparamskey, params, libctx, propq);
184    if (ctx2 == NULL)
185        goto cleanup;
186    if (EVP_PKEY_param_check(ctx2) <= 0) {
187        fprintf(stderr, "EVP_PKEY_param_check() failed\n");
188        goto cleanup;
189    }
190
191    if (!dsa_print_key(EVP_PKEY_CTX_get0_pkey(ctx2), 0, libctx, propq))
192        goto cleanup;
193
194    rv = EXIT_SUCCESS;
195cleanup:
196    EVP_PKEY_free(dsaparamskey);
197    EVP_PKEY_CTX_free(ctx2);
198    EVP_PKEY_CTX_free(ctx1);
199    EVP_PKEY_CTX_free(ctx);
200    BIO_free(in);
201    return rv;
202}
203