1*2175Sjp161948=pod 2*2175Sjp161948 3*2175Sjp161948=head1 NAME 4*2175Sjp161948 5*2175Sjp161948BIO_f_cipher, BIO_set_cipher, BIO_get_cipher_status, BIO_get_cipher_ctx - cipher BIO filter 6*2175Sjp161948 7*2175Sjp161948=head1 SYNOPSIS 8*2175Sjp161948 9*2175Sjp161948 #include <openssl/bio.h> 10*2175Sjp161948 #include <openssl/evp.h> 11*2175Sjp161948 12*2175Sjp161948 BIO_METHOD * BIO_f_cipher(void); 13*2175Sjp161948 void BIO_set_cipher(BIO *b,const EVP_CIPHER *cipher, 14*2175Sjp161948 unsigned char *key, unsigned char *iv, int enc); 15*2175Sjp161948 int BIO_get_cipher_status(BIO *b) 16*2175Sjp161948 int BIO_get_cipher_ctx(BIO *b, EVP_CIPHER_CTX **pctx) 17*2175Sjp161948 18*2175Sjp161948=head1 DESCRIPTION 19*2175Sjp161948 20*2175Sjp161948BIO_f_cipher() returns the cipher BIO method. This is a filter 21*2175Sjp161948BIO that encrypts any data written through it, and decrypts any data 22*2175Sjp161948read from it. It is a BIO wrapper for the cipher routines 23*2175Sjp161948EVP_CipherInit(), EVP_CipherUpdate() and EVP_CipherFinal(). 24*2175Sjp161948 25*2175Sjp161948Cipher BIOs do not support BIO_gets() or BIO_puts(). 26*2175Sjp161948 27*2175Sjp161948BIO_flush() on an encryption BIO that is being written through is 28*2175Sjp161948used to signal that no more data is to be encrypted: this is used 29*2175Sjp161948to flush and possibly pad the final block through the BIO. 30*2175Sjp161948 31*2175Sjp161948BIO_set_cipher() sets the cipher of BIO B<b> to B<cipher> using key B<key> 32*2175Sjp161948and IV B<iv>. B<enc> should be set to 1 for encryption and zero for 33*2175Sjp161948decryption. 34*2175Sjp161948 35*2175Sjp161948When reading from an encryption BIO the final block is automatically 36*2175Sjp161948decrypted and checked when EOF is detected. BIO_get_cipher_status() 37*2175Sjp161948is a BIO_ctrl() macro which can be called to determine whether the 38*2175Sjp161948decryption operation was successful. 39*2175Sjp161948 40*2175Sjp161948BIO_get_cipher_ctx() is a BIO_ctrl() macro which retrieves the internal 41*2175Sjp161948BIO cipher context. The retrieved context can be used in conjunction 42*2175Sjp161948with the standard cipher routines to set it up. This is useful when 43*2175Sjp161948BIO_set_cipher() is not flexible enough for the applications needs. 44*2175Sjp161948 45*2175Sjp161948=head1 NOTES 46*2175Sjp161948 47*2175Sjp161948When encrypting BIO_flush() B<must> be called to flush the final block 48*2175Sjp161948through the BIO. If it is not then the final block will fail a subsequent 49*2175Sjp161948decrypt. 50*2175Sjp161948 51*2175Sjp161948When decrypting an error on the final block is signalled by a zero 52*2175Sjp161948return value from the read operation. A successful decrypt followed 53*2175Sjp161948by EOF will also return zero for the final read. BIO_get_cipher_status() 54*2175Sjp161948should be called to determine if the decrypt was successful. 55*2175Sjp161948 56*2175Sjp161948As always, if BIO_gets() or BIO_puts() support is needed then it can 57*2175Sjp161948be achieved by preceding the cipher BIO with a buffering BIO. 58*2175Sjp161948 59*2175Sjp161948=head1 RETURN VALUES 60*2175Sjp161948 61*2175Sjp161948BIO_f_cipher() returns the cipher BIO method. 62*2175Sjp161948 63*2175Sjp161948BIO_set_cipher() does not return a value. 64*2175Sjp161948 65*2175Sjp161948BIO_get_cipher_status() returns 1 for a successful decrypt and 0 66*2175Sjp161948for failure. 67*2175Sjp161948 68*2175Sjp161948BIO_get_cipher_ctx() currently always returns 1. 69*2175Sjp161948 70*2175Sjp161948=head1 EXAMPLES 71*2175Sjp161948 72*2175Sjp161948TBA 73*2175Sjp161948 74*2175Sjp161948=head1 SEE ALSO 75*2175Sjp161948 76*2175Sjp161948TBA 77