| =pod |
| |
| =head1 NAME |
| |
| PKCS7_encrypt - create a PKCS#7 envelopedData structure |
| |
| =head1 SYNOPSIS |
| |
| #include <openssl/pkcs7.h> |
| |
| PKCS7 *PKCS7_encrypt(STACK_OF(X509) *certs, BIO *in, const EVP_CIPHER *cipher, int flags); |
| |
| =head1 DESCRIPTION |
| |
| PKCS7_encrypt() creates and returns a PKCS#7 envelopedData structure. B<certs> |
| is a list of recipient certificates. B<in> is the content to be encrypted. |
| B<cipher> is the symmetric cipher to use. B<flags> is an optional set of flags. |
| |
| =head1 NOTES |
| |
| Only RSA keys are supported in PKCS#7 and envelopedData so the recipient |
| certificates supplied to this function must all contain RSA public keys, though |
| they do not have to be signed using the RSA algorithm. |
| |
| EVP_des_ede3_cbc() (triple DES) is the algorithm of choice for S/MIME use |
| because most clients will support it. |
| |
| Some old "export grade" clients may only support weak encryption using 40 or 64 |
| bit RC2. These can be used by passing EVP_rc2_40_cbc() and EVP_rc2_64_cbc() |
| respectively. |
| |
| The algorithm passed in the B<cipher> parameter must support ASN1 encoding of |
| its parameters. |
| |
| Many browsers implement a "sign and encrypt" option which is simply an S/MIME |
| envelopedData containing an S/MIME signed message. This can be readily produced |
| by storing the S/MIME signed message in a memory BIO and passing it to |
| PKCS7_encrypt(). |
| |
| The following flags can be passed in the B<flags> parameter. |
| |
| If the B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are |
| prepended to the data. |
| |
| Normally the supplied content is translated into MIME canonical format (as |
| required by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation |
| occurs. This option should be used if the supplied data is in binary format |
| otherwise the translation will corrupt it. If B<PKCS7_BINARY> is set then |
| B<PKCS7_TEXT> is ignored. |
| |
| If the B<PKCS7_STREAM> flag is set a partial B<PKCS7> structure is output |
| suitable for streaming I/O: no data is read from the BIO B<in>. |
| |
| =head1 NOTES |
| |
| If the flag B<PKCS7_STREAM> is set the returned B<PKCS7> structure is B<not> |
| complete and outputting its contents via a function that does not |
| properly finalize the B<PKCS7> structure will give unpredictable |
| results. |
| |
| Several functions including SMIME_write_PKCS7(), i2d_PKCS7_bio_stream(), |
| PEM_write_bio_PKCS7_stream() finalize the structure. Alternatively finalization |
| can be performed by obtaining the streaming ASN1 B<BIO> directly using |
| BIO_new_PKCS7(). |
| |
| =head1 RETURN VALUES |
| |
| PKCS7_encrypt() returns either a PKCS7 structure or NULL if an error occurred. |
| The error can be obtained from ERR_get_error(3). |
| |
| =head1 SEE ALSO |
| |
| L<ERR_get_error(3)>, L<PKCS7_decrypt(3)> |
| |
| =head1 HISTORY |
| |
| The B<PKCS7_STREAM> flag was added in OpenSSL 1.0.0. |
| |
| =head1 COPYRIGHT |
| |
| Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved. |
| |
| Licensed under the OpenSSL license (the "License"). You may not use |
| this file except in compliance with the License. You can obtain a copy |
| in the file LICENSE in the source distribution or at |
| L<https://www.openssl.org/source/license.html>. |
| |
| =cut |
