BIO_f_cipher(3)             OpenSSL             BIO_f_cipher(3)





NAME
       BIO_f_cipher, BIO_set_cipher, BIO_get_cipher_status,
       BIO_get_cipher_ctx - cipher BIO filter

SYNOPSIS
        #include <openssl/bio.h>
        #include <openssl/evp.h>

        BIO_METHOD *   BIO_f_cipher(void);
        void BIO_set_cipher(BIO *b,const EVP_CIPHER *cipher,
                       unsigned char *key, unsigned char *iv, int enc);
        int BIO_get_cipher_status(BIO *b)
        int BIO_get_cipher_ctx(BIO *b, EVP_CIPHER_CTX **pctx)

DESCRIPTION
       BIO_f_cipher() 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 EVP_CipherInit(), EVP_CipherUp-
       date() and EVP_CipherFinal().

       Cipher BIOs do not support BIO_gets() or BIO_puts().

       BIO_flush() 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.

       BIO_set_cipher() sets the cipher of BIO b to cipher
       using key key and IV iv. enc 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. BIO_get_cipher_status() is a BIO_ctrl() macro
       which can be called to determine whether the decryption
       operation was successful.

       BIO_get_cipher_ctx() is a BIO_ctrl() 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
       BIO_set_cipher() is not flexible enough for the applica-
       tions needs.

NOTES
       When encrypting BIO_flush() must 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 suc-
       cessful decrypt followed by EOF will also return zero
       for the final read. BIO_get_cipher_status() should be
       called to determine if the decrypt was successful.

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

RETURN VALUES
       BIO_f_cipher() returns the cipher BIO method.

       BIO_set_cipher() does not return a value.

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

       BIO_get_cipher_ctx() currently always returns 1.

EXAMPLES
       TBA

SEE ALSO
       TBA



0.9.7c                     2003-02-27           BIO_f_cipher(3)
