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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>

	const 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 signaled 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.

COPYRIGHT
       Copyright 2000-2016 The OpenSSL Project Authors.	All Rights Reserved.

       Licensed	under the OpenSSL license (the "License").  You	may not	use
       this file except	in compliance with the License.	 You can obtain	a copy
       in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.

1.1.1d				  2019-09-10		       BIO_F_CIPHER(3)

NAME | SYNOPSIS | DESCRIPTION | NOTES | RETURN VALUES | COPYRIGHT

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