PKCS7_DECRYPT(3)

NAME
PKCS7_decrypt - decrypt content from a PKCS#7 envelopedData structure

SYNOPSIS
 #include <openssl/pkcs7.h>

 int PKCS7_decrypt(PKCS7 *p7, EVP_PKEY *pkey, X509 *cert, BIO *data, int flags);

DESCRIPTION
PKCS7_decrypt() extracts and decrypts the content from a PKCS#7 envelopedData structure. pkey is the private key of the recipient, cert is the recipients certificate, data is a BIO to write the content to and flags is an optional set of flags.

NOTES
Although the recipients certificate is not needed to decrypt the data it is needed to locate the appropriate (of possible several) recipients in the PKCS#7 structure.

When RSA PKCS#1 v1.5 Key Transport is in use, the invoked EVP_PKEY_decrypt() will use implicit rejection mechanism. It always returns the result of RSA decryption of the symmetric key to avoid Marvin attack. This result is deterministic and can happen to match the symmetric cipher used for the content encryption. In case when the certificate is not provided, the last RecipientInfo producing the key looking valid will be used. It may cause getting garbage content on decryption.

The following flags can be passed in the flags parameter.

If the PKCS7_TEXT flag is set MIME headers for type text/plain are deleted from the content. If the content is not of type text/plain then an error is returned.

RETURN VALUES
PKCS7_decrypt() returns either 1 for success or 0 for failure. The error can be obtained from ERR_get_error(3)

BUGS
PKCS7_decrypt() must be passed the correct recipient key and certificate. It would be better if it could look up the correct key and certificate from a database.

SEE ALSO
ERR_get_error(3), PKCS7_encrypt(3), EVP_PKEY_decrypt(3)

COPYRIGHT
Copyright 2002-2026 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (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 <https://www.openssl.org/source/license.html>.