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)
DESCRIPTIONBIO_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 VALUESBIO_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
16/Sep/2000 0.9.6j BIO_f_cipher(3)
