.\" $OpenBSD: PKCS7_encrypt.3,v 1.11 2020/06/03 13:41:27 schwarze Exp $ .\" full merge up to: OpenSSL e9b77246 Jan 20 19:58:49 2017 +0100 .\" .\" This file was written by Dr. Stephen Henson . .\" Copyright (c) 2002, 2006, 2007, 2008, 2009 The OpenSSL Project. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in .\" the documentation and/or other materials provided with the .\" distribution. .\" .\" 3. All advertising materials mentioning features or use of this .\" software must display the following acknowledgment: .\" "This product includes software developed by the OpenSSL Project .\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" .\" .\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to .\" endorse or promote products derived from this software without .\" prior written permission. For written permission, please contact .\" openssl-core@openssl.org. .\" .\" 5. Products derived from this software may not be called "OpenSSL" .\" nor may "OpenSSL" appear in their names without prior written .\" permission of the OpenSSL Project. .\" .\" 6. Redistributions of any form whatsoever must retain the following .\" acknowledgment: .\" "This product includes software developed by the OpenSSL Project .\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" .\" .\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY .\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR .\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR .\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: June 3 2020 $ .Dt PKCS7_ENCRYPT 3 .Os .Sh NAME .Nm PKCS7_encrypt .Nd create a PKCS#7 envelopedData structure .Sh SYNOPSIS .In openssl/pkcs7.h .Ft PKCS7 * .Fo PKCS7_encrypt .Fa "STACK_OF(X509) *certs" .Fa "BIO *in" .Fa "const EVP_CIPHER *cipher" .Fa "int flags" .Fc .Sh DESCRIPTION .Fn PKCS7_encrypt creates and returns a PKCS#7 envelopedData structure. .Fa certs is a list of recipient certificates. .Fa in is the content to be encrypted. .Fa cipher is the symmetric cipher to use. .Fa flags is an optional set of flags. .Pp 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. .Pp The algorithm passed in the .Fa cipher parameter must support ASN.1 encoding of its parameters. .Pp 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 .Vt BIO and passing it to .Fn PKCS7_encrypt . .Pp The following flags can be passed in the .Fa flags parameter. .Pp If the .Dv PKCS7_TEXT flag is set, MIME headers for type .Sy text/plain are prepended to the data. .Pp Normally the supplied content is translated into MIME canonical format (as required by the S/MIME specifications). If .Dv 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 .Dv PKCS7_BINARY is set, then .Dv PKCS7_TEXT is ignored. .Pp If the .Dv PKCS7_STREAM flag is set, a partial .Vt PKCS7 structure is output suitable for streaming I/O: no data is read from .Fa in . .Pp If the flag .Dv PKCS7_STREAM is set, the returned .Vt PKCS7 structure is .Sy not complete and outputting its contents via a function that does not properly finalize the .Vt PKCS7 structure will give unpredictable results. .Pp Several functions including .Xr PKCS7_final 3 , .Xr SMIME_write_PKCS7 3 , .Xr PEM_write_bio_PKCS7_stream 3 , and .Xr i2d_PKCS7_bio_stream 3 finalize the structure. Alternatively finalization can be performed by obtaining the streaming ASN.1 .Vt BIO directly using .Fn BIO_new_PKCS7 . .Sh RETURN VALUES .Fn PKCS7_encrypt returns either a .Vt PKCS7 structure or .Dv NULL if an error occurred. The error can be obtained from .Xr ERR_get_error 3 . .Sh SEE ALSO .Xr PKCS7_decrypt 3 , .Xr PKCS7_final 3 , .Xr PKCS7_new 3 , .Xr PKCS7_sign 3 .Sh HISTORY .Fn PKCS7_encrypt first appeared in OpenSSL 0.9.5 and has been available since .Ox 2.7 . .Pp The .Dv PKCS7_STREAM flag was first supported in OpenSSL 1.0.0.