RSA_private_encrypt 3 2003-07-24 0.9.9-dev OpenSSL

NAME

RSA_private_encrypt, RSA_public_decrypt - low level signature operations

LIBRARY

libcrypto, -lcrypto

SYNOPSIS


 #include 


 int RSA_private_encrypt(int flen, unsigned char *from,
    unsigned char *to, RSA *rsa, int padding);


 int RSA_public_decrypt(int flen, unsigned char *from,
    unsigned char *to, RSA *rsa, int padding);

DESCRIPTION

These functions handle RSA signatures at a low level.

_R_S_A___p_r_i_v_a_t_e___e_n_c_r_y_p_t_(_) signs the fflleenn bytes at ffrroomm (usually a message digest with an algorithm identifier) using the private key rrssaa and stores the signature in ttoo. ttoo must point to RRSSAA__ssiizzee((rrssaa)) bytes of memory.

ppaaddddiinngg denotes one of the following modes:

RSA_PKCS1_PADDING PKCS #1 v1.5 padding. This function does not handle the
aallggoorriitthhmmIIddeennttiiffiieerr specified in PKCS #1. When generating or verifying PKCS #1 signatures, _R_S_A___s_i_g_n(3) and _R_S_A___v_e_r_i_f_y(3) should be used.
RSA_NO_PADDING Raw RSA signature. This mode should _o_n_l_y be used to implement
cryptographically sound padding modes in the application code. Signing user data directly with RSA is insecure.

_R_S_A___p_u_b_l_i_c___d_e_c_r_y_p_t_(_) recovers the message digest from the fflleenn bytes long signature at ffrroomm using the signer's public key rrssaa. ttoo must point to a memory section large enough to hold the message digest (which is smaller than RRSSAA__ssiizzee((rrssaa)) -- 1111). ppaaddddiinngg is the padding mode that was used to sign the data.

RETURN VALUES

_R_S_A___p_r_i_v_a_t_e___e_n_c_r_y_p_t_(_) returns the size of the signature (i.e., RSA_size(rsa)). _R_S_A___p_u_b_l_i_c___d_e_c_r_y_p_t_(_) returns the size of the recovered message digest.

On error, -1 is returned; the error codes can be obtained by _E_R_R___g_e_t___e_r_r_o_r(3).

SEE ALSO

_E_R_R___g_e_t___e_r_r_o_r(3), _o_p_e_n_s_s_l___r_s_a(3), _R_S_A___s_i_g_n(3), _R_S_A___v_e_r_i_f_y(3)

HISTORY

The ppaaddddiinngg argument was added in SSLeay 0.8. RSA_NO_PADDING is available since SSLeay 0.9.0.