| =pod |
| |
| =head1 NAME |
| |
| BIO_f_cipher, BIO_set_cipher, BIO_get_cipher_status, BIO_get_cipher_ctx - cipher BIO filter |
| |
| =head1 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) |
| |
| =head1 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<b> to B<cipher> using key B<key> |
| and IV B<iv>. B<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. |
| |
| =head1 NOTES |
| |
| When encrypting BIO_flush() B<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. |
| |
| =head1 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. |
| |
| =head1 EXAMPLES |
| |
| TBA |
| |
| =head1 SEE ALSO |
| |
| TBA |
