BIO_f_cipher 3 2003-07-24 0.9.9-dev OpenSSL

NAME

BIO_f_cipher, BIO_set_cipher, BIO_get_cipher_status, BIO_get_cipher_ctx - cipher BIO filter

LIBRARY

libcrypto, -lcrypto

SYNOPSIS


 #include 
 #include 






 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)

DESCRIPTION

_B_I_O___f___c_i_p_h_e_r_(_) 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 _E_V_P___C_i_p_h_e_r_I_n_i_t_(_), _E_V_P___C_i_p_h_e_r_U_p_d_a_t_e_(_) and _E_V_P___C_i_p_h_e_r_F_i_n_a_l_(_).

Cipher BIOs do not support _B_I_O___g_e_t_s_(_) or _B_I_O___p_u_t_s_(_).

_B_I_O___f_l_u_s_h_(_) 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.

_B_I_O___s_e_t___c_i_p_h_e_r_(_) sets the cipher of BIO bb to cciipphheerr using key kkeeyy and IV iivv. eenncc 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. _B_I_O___g_e_t___c_i_p_h_e_r___s_t_a_t_u_s_(_) is a _B_I_O___c_t_r_l_(_) macro which can be called to determine whether the decryption operation was successful.

_B_I_O___g_e_t___c_i_p_h_e_r___c_t_x_(_) is a _B_I_O___c_t_r_l_(_) 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 _B_I_O___s_e_t___c_i_p_h_e_r_(_) is not flexible enough for the applications needs.

NOTES

When encrypting _B_I_O___f_l_u_s_h_(_) mmuusstt 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. _B_I_O___g_e_t___c_i_p_h_e_r___s_t_a_t_u_s_(_) should be called to determine if the decrypt was successful.

As always, if _B_I_O___g_e_t_s_(_) or _B_I_O___p_u_t_s_(_) support is needed then it can be achieved by preceding the cipher BIO with a buffering BIO.

RETURN VALUES

_B_I_O___f___c_i_p_h_e_r_(_) returns the cipher BIO method.

_B_I_O___s_e_t___c_i_p_h_e_r_(_) does not return a value.

_B_I_O___g_e_t___c_i_p_h_e_r___s_t_a_t_u_s_(_) returns 1 for a successful decrypt and 0 for failure.

_B_I_O___g_e_t___c_i_p_h_e_r___c_t_x_(_) currently always returns 1.

EXAMPLES

TBA

SEE ALSO

TBA