1=pod 2 3=head1 NAME 4 5PKCS7_encrypt_ex, PKCS7_encrypt 6- create a PKCS#7 envelopedData structure 7 8=head1 SYNOPSIS 9 10 #include <openssl/pkcs7.h> 11 12 PKCS7 *PKCS7_encrypt_ex(STACK_OF(X509) *certs, BIO *in, 13 const EVP_CIPHER *cipher, int flags, 14 OSSL_LIB_CTX *libctx, const char *propq); 15 PKCS7 *PKCS7_encrypt(STACK_OF(X509) *certs, BIO *in, const EVP_CIPHER *cipher, 16 int flags); 17 18=head1 DESCRIPTION 19 20PKCS7_encrypt_ex() creates and returns a PKCS#7 envelopedData structure. 21I<certs> is a list of recipient certificates. I<in> is the content to be 22encrypted. I<cipher> is the symmetric cipher to use. I<flags> is an optional set 23of flags. The library context I<libctx> and the property query I<propq> are used 24when retrieving algorithms from providers. 25 26Only RSA keys are supported in PKCS#7 and envelopedData so the recipient 27certificates supplied to this function must all contain RSA public keys, though 28they do not have to be signed using the RSA algorithm. 29 30EVP_des_ede3_cbc() (triple DES) is the algorithm of choice for S/MIME use 31because most clients will support it. 32 33Some old "export grade" clients may only support weak encryption using 40 or 64 34bit RC2. These can be used by passing EVP_rc2_40_cbc() and EVP_rc2_64_cbc() 35respectively. 36 37The algorithm passed in the B<cipher> parameter must support ASN1 encoding of 38its parameters. 39 40Many browsers implement a "sign and encrypt" option which is simply an S/MIME 41envelopedData containing an S/MIME signed message. This can be readily produced 42by storing the S/MIME signed message in a memory BIO and passing it to 43PKCS7_encrypt(). 44 45The following flags can be passed in the B<flags> parameter. 46 47If the B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are 48prepended to the data. 49 50Normally the supplied content is translated into MIME canonical format (as 51required by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation 52occurs. This option should be used if the supplied data is in binary format 53otherwise the translation will corrupt it. If B<PKCS7_BINARY> is set then 54B<PKCS7_TEXT> is ignored. 55 56If the B<PKCS7_STREAM> flag is set a partial B<PKCS7> structure is output 57suitable for streaming I/O: no data is read from the BIO B<in>. 58 59If the flag B<PKCS7_STREAM> is set the returned B<PKCS7> structure is B<not> 60complete and outputting its contents via a function that does not 61properly finalize the B<PKCS7> structure will give unpredictable 62results. 63 64Several functions including SMIME_write_PKCS7(), i2d_PKCS7_bio_stream(), 65PEM_write_bio_PKCS7_stream() finalize the structure. Alternatively finalization 66can be performed by obtaining the streaming ASN1 B<BIO> directly using 67BIO_new_PKCS7(). 68 69PKCS7_encrypt() is similar to PKCS7_encrypt_ex() but uses default 70values of NULL for the library context I<libctx> and the property query I<propq>. 71 72=head1 RETURN VALUES 73 74PKCS7_encrypt_ex() and PKCS7_encrypt() return either a PKCS7 structure 75or NULL if an error occurred. The error can be obtained from ERR_get_error(3). 76 77=head1 SEE ALSO 78 79L<ERR_get_error(3)>, L<PKCS7_decrypt(3)> 80 81=head1 HISTORY 82 83The function PKCS7_encrypt_ex() was added in OpenSSL 3.0. 84 85The B<PKCS7_STREAM> flag was added in OpenSSL 1.0.0. 86 87=head1 COPYRIGHT 88 89Copyright 2002-2020 The OpenSSL Project Authors. All Rights Reserved. 90 91Licensed under the Apache License 2.0 (the "License"). You may not use 92this file except in compliance with the License. You can obtain a copy 93in the file LICENSE in the source distribution or at 94L<https://www.openssl.org/source/license.html>. 95 96=cut 97