BIOfcipher(3) OpenSSL BIOfcipher(3)

NAME
       BIOfcipher, BIOsetcipher, BIOgetcipherstatus, BIOgetcipherctx
       - cipher BIO filter

SYNOPSIS
        #include 
        #include 

        BIOMETHOD *   BIOfcipher(void);
        void BIOsetcipher(BIO *b,const EVPCIPHER *cipher,
                       unsigned char *key, unsigned char *iv, int enc);
        int BIOgetcipherstatus(BIO *b)
        int BIOgetcipherctx(BIO *b, EVPCIPHERCTX **pctx)

DESCRIPTION
       BIOfcipher() returns the cipher BIO method. This is a filter BIO that
       encrypts any data written through it, and decrypts any data read from
       it. It is a BIO wrapper for the cipher routines EVPCipherInit(),
       EVPCipherUpdate() and EVPCipherFinal().

       Cipher BIOs do not support BIOgets() or BIOputs().

       BIOflush() on an encryption BIO that is being written through is used
       to signal that no more data is to be encrypted: this is used to flush
       and possibly pad the final block through the BIO.

       BIOsetcipher() sets the cipher of BIO bb to cciipphheerr using key kkeeyy and
       IV iivv. eenncc should be set to 1 for encryption and zero for decryption.

       When reading from an encryption BIO the final block is automatically
       decrypted and checked when EOF is detected. BIOgetcipherstatus() is
       a BIOctrl() macro which can be called to determine whether the
       decryption operation was successful.

       BIOgetcipherctx() is a BIOctrl() macro which retrieves the internal
       BIO cipher context. The retrieved context can be used in conjunction
       with the standard cipher routines to set it up. This is useful when
       BIOsetcipher() is not flexible enough for the applications needs.

NNOOTTEESS
       When encrypting BIOflush() mmuusstt be called to flush the final block
       through the BIO. If it is not then the final block will fail a
       subsequent decrypt.

       When decrypting an error on the final block is signalled by a zero
       return value from the read operation. A successful decrypt followed by
       EOF will also return zero for the final read. BIOgetcipherstatus()
       should be called to determine if the decrypt was successful.

       As always, if BIOgets() or BIOputs() support is needed then it can be
       achieved by preceding the cipher BIO with a buffering BIO.

RETURN VALUES
       BIOfcipher() returns the cipher BIO method.

       BIOsetcipher() does not return a value.

       BIOgetcipherstatus() returns 1 for a successful decrypt and 0 for
       failure.

       BIOgetcipherctx() currently always returns 1.

EEXXAAMMPPLLEESS
       TBA

SEE ALSO
       TBA



0.9.7l                            2003-02-27                   BIOfcipher(3)