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      1 /*
      2  * Copyright 2007-2023 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 encrypt example */
     11 #include <openssl/pem.h>
     12 #include <openssl/pkcs7.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 *rcert = NULL;
     19     STACK_OF(X509) *recips = NULL;
     20     PKCS7 *p7 = NULL;
     21     int ret = EXIT_FAILURE;
     22 
     23     /*
     24      * for streaming set PKCS7_STREAM
     25      */
     26     int flags = PKCS7_STREAM;
     27 
     28     OpenSSL_add_all_algorithms();
     29     ERR_load_crypto_strings();
     30 
     31     /* Read in recipient certificate */
     32     tbio = BIO_new_file("signer.pem", "r");
     33 
     34     if (!tbio)
     35         goto err;
     36 
     37     rcert = PEM_read_bio_X509(tbio, NULL, 0, NULL);
     38 
     39     if (!rcert)
     40         goto err;
     41 
     42     /* Create recipient STACK and add recipient cert to it */
     43     recips = sk_X509_new_null();
     44 
     45     if (!recips || !sk_X509_push(recips, rcert))
     46         goto err;
     47 
     48     /*
     49      * OSSL_STACK_OF_X509_free() will free up recipient STACK and its contents
     50      * so set rcert to NULL so it isn't freed up twice.
     51      */
     52     rcert = NULL;
     53 
     54     /* Open content being encrypted */
     55 
     56     in = BIO_new_file("encr.txt", "r");
     57 
     58     if (!in)
     59         goto err;
     60 
     61     /* encrypt content */
     62     p7 = PKCS7_encrypt(recips, in, EVP_des_ede3_cbc(), flags);
     63 
     64     if (!p7)
     65         goto err;
     66 
     67     out = BIO_new_file("smencr.txt", "w");
     68     if (!out)
     69         goto err;
     70 
     71     /* Write out S/MIME message */
     72     if (!SMIME_write_PKCS7(out, p7, in, flags))
     73         goto err;
     74 
     75     printf("Success\n");
     76 
     77     ret = EXIT_SUCCESS;
     78 err:
     79     if (ret != EXIT_SUCCESS) {
     80         fprintf(stderr, "Error Encrypting Data\n");
     81         ERR_print_errors_fp(stderr);
     82     }
     83     PKCS7_free(p7);
     84     X509_free(rcert);
     85     OSSL_STACK_OF_X509_free(recips);
     86     BIO_free(in);
     87     BIO_free(out);
     88     BIO_free(tbio);
     89     return ret;
     90 }
     91