BIO_f_cipher, BIO_set_cipher, BIO_get_cipher_status, BIO_get_cipher_ctx - cipher
BIO filter
#include <openssl/bio.h>
#include <openssl/evp.h>
const BIO_METHOD *BIO_f_cipher(void);
int BIO_set_cipher(BIO *b, const EVP_CIPHER *cipher,
const unsigned char *key, const unsigned char *iv, int enc);
int BIO_get_cipher_status(BIO *b);
int BIO_get_cipher_ctx(BIO *b, EVP_CIPHER_CTX **pctx);
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.
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.
BIO_f_cipher() returns the cipher BIO method.
BIO_set_cipher() returns 1 for success and 0 for failure.
BIO_get_cipher_status() returns 1 for a successful decrypt and <=0 for
failure.
BIO_get_cipher_ctx() returns 1 for success and <=0 for failure.
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Licensed under the Apache License 2.0 (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
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https://www.openssl.org/source/license.html>.