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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_CipherUpdate() 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 applications 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 successful 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



0.9.8                                            2009-04-03                                  BIO_f_cipher(3)