demos/signature/rsa_pss_hash.c

   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 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <openssl/core_names.h>
  13 #include <openssl/evp.h>
  14 #include <openssl/rsa.h>
  15 #include <openssl/params.h>
  16 #include <openssl/err.h>
  17 #include <openssl/bio.h>
  18 #include "rsa_pss.h"
  19
  20 /* The data to be signed. This will be hashed. */
  21 static const char test_message[] =
  22     "This is an example message to be signed.";
  23
  24 /* A property query used for selecting algorithm implementations. */
  25 static const char *propq = NULL;
  26
  27 /*
  28  * This function demonstrates RSA signing of an arbitrary-length message.
  29  * Hashing is performed automatically. In this example, SHA-256 is used. If you
  30  * have already hashed your message and simply want to sign the hash directly,
  31  * see rsa_pss_direct.c.
  32  */
  33 static int sign(OSSL_LIB_CTX *libctx, unsigned char **sig, size_t *sig_len)
  34 {
  35     int rv = 0;
  36     EVP_PKEY *pkey = NULL;
  37     EVP_MD_CTX *mctx = NULL;
  38     OSSL_PARAM params[2], *p = params;
  39     const unsigned char *ppriv_key = NULL;
  40
  41     *sig = NULL;
  42
  43     /* Load DER-encoded RSA private key. */
  44     ppriv_key = rsa_priv_key;
  45     pkey = d2i_PrivateKey_ex(EVP_PKEY_RSA, NULL, &ppriv_key,
  46                              sizeof(rsa_priv_key), libctx, propq);
  47     if (pkey == NULL) {
  48         fprintf(stderr, "Failed to load private key\n");
  49         goto end;
  50     }
  51
  52     /* Create MD context used for signing. */
  53     mctx = EVP_MD_CTX_new();
  54     if (mctx == NULL) {
  55         fprintf(stderr, "Failed to create MD context\n");
  56         goto end;
  57     }
  58
  59     /* Initialize MD context for signing. */
  60     *p++ = OSSL_PARAM_construct_utf8_string(OSSL_SIGNATURE_PARAM_PAD_MODE,
  61                                             OSSL_PKEY_RSA_PAD_MODE_PSS, 0);
  62     *p = OSSL_PARAM_construct_end();
  63
  64     if (EVP_DigestSignInit_ex(mctx, NULL, "SHA256", libctx, propq,
  65                               pkey, params) == 0) {
  66         fprintf(stderr, "Failed to initialize signing context\n");
  67         goto end;
  68     }
  69
  70     /*
  71      * Feed data to be signed into the algorithm. This may
  72      * be called multiple times.
  73      */
  74     if (EVP_DigestSignUpdate(mctx, test_message, sizeof(test_message)) == 0) {
  75         fprintf(stderr, "Failed to hash message into signing context\n");
  76         goto end;
  77     }
  78
  79     /* Determine signature length. */
  80     if (EVP_DigestSignFinal(mctx, NULL, sig_len) == 0) {
  81         fprintf(stderr, "Failed to get signature length\n");
  82         goto end;
  83     }
  84
  85     /* Allocate memory for signature. */
  86     *sig = OPENSSL_malloc(*sig_len);
  87     if (*sig == NULL) {
  88         fprintf(stderr, "Failed to allocate memory for signature\n");
  89         goto end;
  90     }
  91
  92     /* Generate signature. */
  93     if (EVP_DigestSignFinal(mctx, *sig, sig_len) == 0) {
  94         fprintf(stderr, "Failed to sign\n");
  95         goto end;
  96     }
  97
  98     rv = 1;
  99 end:
 100     EVP_MD_CTX_free(mctx);
 101     EVP_PKEY_free(pkey);
 102
 103     if (rv == 0)
 104         OPENSSL_free(*sig);
 105
 106     return rv;
 107 }
 108
 109 /*
 110  * This function demonstrates verification of an RSA signature over an
 111  * arbitrary-length message using the PSS signature scheme. Hashing is performed
 112  * automatically.
 113  */
 114 static int verify(OSSL_LIB_CTX *libctx, const unsigned char *sig, size_t sig_len)
 115 {
 116     int rv = 0;
 117     EVP_PKEY *pkey = NULL;
 118     EVP_MD_CTX *mctx = NULL;
 119     OSSL_PARAM params[2], *p = params;
 120     const unsigned char *ppub_key = NULL;
 121
 122     /* Load DER-encoded RSA public key. */
 123     ppub_key = rsa_pub_key;
 124     pkey = d2i_PublicKey(EVP_PKEY_RSA, NULL, &ppub_key, sizeof(rsa_pub_key));
 125     if (pkey == NULL) {
 126         fprintf(stderr, "Failed to load public key\n");
 127         goto end;
 128     }
 129
 130     /* Create MD context used for verification. */
 131     mctx = EVP_MD_CTX_new();
 132     if (mctx == NULL) {
 133         fprintf(stderr, "Failed to create MD context\n");
 134         goto end;
 135     }
 136
 137     /* Initialize MD context for verification. */
 138     *p++ = OSSL_PARAM_construct_utf8_string(OSSL_SIGNATURE_PARAM_PAD_MODE,
 139                                             OSSL_PKEY_RSA_PAD_MODE_PSS, 0);
 140     *p = OSSL_PARAM_construct_end();
 141
 142     if (EVP_DigestVerifyInit_ex(mctx, NULL, "SHA256", libctx, propq,
 143                                 pkey, params) == 0) {
 144         fprintf(stderr, "Failed to initialize signing context\n");
 145         goto end;
 146     }
 147
 148     /*
 149      * Feed data to be signed into the algorithm. This may
 150      * be called multiple times.
 151      */
 152     if (EVP_DigestVerifyUpdate(mctx, test_message, sizeof(test_message)) == 0) {
 153         fprintf(stderr, "Failed to hash message into signing context\n");
 154         goto end;
 155     }
 156
 157     /* Verify signature. */
 158     if (EVP_DigestVerifyFinal(mctx, sig, sig_len) == 0) {
 159         fprintf(stderr, "Failed to verify signature; "
 160                 "signature may be invalid\n");
 161         goto end;
 162     }
 163
 164     rv = 1;
 165 end:
 166     EVP_MD_CTX_free(mctx);
 167     EVP_PKEY_free(pkey);
 168     return rv;
 169 }
 170
 171 int main(int argc, char **argv)
 172 {
 173     int rv = 1;
 174     OSSL_LIB_CTX *libctx = NULL;
 175     unsigned char *sig = NULL;
 176     size_t sig_len = 0;
 177
 178     if (sign(libctx, &sig, &sig_len) == 0)
 179         goto end;
 180
 181     if (verify(libctx, sig, sig_len) == 0)
 182         goto end;
 183
 184     rv = 0;
 185 end:
 186     OPENSSL_free(sig);
 187     OSSL_LIB_CTX_free(libctx);
 188     return rv;
 189 }