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