PKCS7_decrypt - decrypt content from a PKCS#7 envelopedData structure
Synopsis int PKCS7_decrypt(PKCS7 *p7, EVP_PKEY *pkey,
X509 *cert, BIO *data, int flags);
DESCRIPTIONPKCS7_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. NOTESOpenSSL_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 PKCS#7 structure.
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 VALUESPKCS7_decrypt() returns either 1 for success or 0 for failure.
The error can be obtained from ERR_get_error(3) RestrictionsPKCS7_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.
The lack of single pass processing and need to hold all data
in memory as mentioned in PKCS7_sign() also applies to PKCS7_verify().
SEE ALSOERR_get_error(3) , PKCS7_encrypt(3) HISTORYPKCS7_decrypt() was added to OpenSSL 0.9.5
HP Open Source Security for OpenVMS Volume 2:... 
CRYPTO Application Programming Interface (API)... 
