CMS_decrypt - decrypt content from a CMS envelopedData structure
int CMS_decrypt(CMS_ContentInfo *cms, EVP_PKEY *pkey, X509 *cert, BIO *dcont, BIO *out, unsigned int flags);
extracts and decrypts the content from a CMS EnvelopedData
is the private key of the recipient, cert
recipient's certificate, out
is a BIO to write the content to and
is an optional set of flags.
parameter is used in the rare case where the encrypted content
is detached. It will normally be set to NULL.
(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()
this case both cert
should be set to NULL.
To process KEKRecipientInfo types CMS_set1_key()
should be called before CMS_decrypt()
set to NULL.
The following flags can be passed in the flags
If the CMS_TEXT
flag is set MIME headers for type text/plain
deleted from the content. If the content is not of type text/plain
an error is returned.
returns either 1 for success or 0 for failure. The error
can be obtained from ERR_get_error(3)
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()
was added to OpenSSL 0.9.8