1 /* 2 * Copyright 2008-2023 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 /* Simple S/MIME signing example */ 11 #include <openssl/pem.h> 12 #include <openssl/cms.h> 13 #include <openssl/err.h> 14 15 int main(int argc, char **argv) 16 { 17 BIO *in = NULL, *out = NULL, *tbio = NULL; 18 X509 *scert = NULL; 19 EVP_PKEY *skey = NULL; 20 CMS_ContentInfo *cms = NULL; 21 int ret = EXIT_FAILURE; 22 23 /* 24 * For simple S/MIME signing use CMS_DETACHED. On OpenSSL 1.0.0 only: for 25 * streaming detached set CMS_DETACHED|CMS_STREAM for streaming 26 * non-detached set CMS_STREAM 27 */ 28 int flags = CMS_DETACHED | CMS_STREAM; 29 30 OpenSSL_add_all_algorithms(); 31 ERR_load_crypto_strings(); 32 33 /* Read in signer certificate and private key */ 34 tbio = BIO_new_file("signer.pem", "r"); 35 36 if (!tbio) 37 goto err; 38 39 scert = PEM_read_bio_X509(tbio, NULL, 0, NULL); 40 41 if (BIO_reset(tbio) < 0) 42 goto err; 43 44 skey = PEM_read_bio_PrivateKey(tbio, NULL, 0, NULL); 45 46 if (!scert || !skey) 47 goto err; 48 49 /* Open content being signed */ 50 51 in = BIO_new_file("sign.txt", "r"); 52 53 if (!in) 54 goto err; 55 56 /* Sign content */ 57 cms = CMS_sign(scert, skey, NULL, in, flags); 58 59 if (!cms) 60 goto err; 61 62 out = BIO_new_file("smout.txt", "w"); 63 if (!out) 64 goto err; 65 66 if (!(flags & CMS_STREAM)) { 67 if (BIO_reset(in) < 0) 68 goto err; 69 } 70 71 /* Write out S/MIME message */ 72 if (!SMIME_write_CMS(out, cms, in, flags)) 73 goto err; 74 75 ret = EXIT_SUCCESS; 76 err: 77 if (ret != EXIT_SUCCESS) { 78 fprintf(stderr, "Error Signing Data\n"); 79 ERR_print_errors_fp(stderr); 80 } 81 82 CMS_ContentInfo_free(cms); 83 X509_free(scert); 84 EVP_PKEY_free(skey); 85 BIO_free(in); 86 BIO_free(out); 87 BIO_free(tbio); 88 return ret; 89 } 90