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CMS_decrypt(3)
NAME
CMS_decrypt - decrypt content from a CMS envelopedData structure
SYNOPSIS
#include <openssl/cms.h>
int CMS_decrypt(CMS_ContentInfo *cms, EVP_PKEY *pkey, X509 *cert, BIO *dcont, BIO *out, unsigned int flags);
DESCRIPTION
CMS_decrypt() extracts and decrypts the content from a CMS
EnvelopedData structure. pkey is the private key of the recipient, cert is the recipient's certificate, out is a BIO to write the content to and
flags is an optional set of flags.
The dcont parameter is used in the rare case where the encrypted content is detached. It will normally be set to NULL.
NOTES
OpenSSL_add_all_algorithms() (or equivalent) should be called
before using this function or errors about unknown algorithms will occur.
Although the recipients certificate is not needed to decrypt the data it is needed to locate the appropriate (of possible several) recipients in the CMS structure. If cert is set to NULL all possible recipients are tried.
It is possible to determine the correct recipient key by other means (for
example looking them up in a database) and setting them in the CMS
structure in advance using the CMS utility functions such as
CMS_set1_pkey(). In this case both cert and pkey should be set to NULL.
To process KEKRecipientInfo types CMS_set1_key() or
CMS_RecipientInfo_set0_key() and
CMS_ReceipientInfo_decrypt() should be called before
CMS_decrypt() and
cert and pkey set to NULL.
The following flags can be passed in the flags parameter.
If the CMS_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
CMS_decrypt() returns either 1 for success or 0 for failure.
The error can be obtained from ERR_get_error(3)
BUGS
The lack of single pass processing and the need to hold all data in memory
as mentioned in CMS_verify() also applies to
CMS_decrypt().
SEE ALSO
ERR_get_error(3), CMS_encrypt(3)
HISTORY
CMS_decrypt() was added to OpenSSL 0.9.8
