BIO_f_cipher, BIO_set_cipher, BIO_get_cipher_status, BIO_get_cipher_ctx - cipher
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)
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()
Cipher BIOs do not support BIO_gets()
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.
sets the cipher of BIO b
and IV iv
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()
macro which can be called to determine whether the
decryption operation was successful.
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
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
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()
support is needed then it
can be achieved by preceding the cipher BIO with a buffering BIO.
returns the cipher BIO method.
does not return a value.
returns 1 for a successful decrypt and 0 for
currently always returns 1.