/usr/man/cat.3/RSA_public_encrypt.3.Z

NAME

       RSA_public_encrypt, RSA_private_decrypt - RSA public key cryptography

SYNOPSIS

        #include <openssl/rsa.h>

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

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

DESCRIPTION

       RSA_public_encrypt() encrypts the flen bytes at from (usually a session
       key) using the public key rsa and stores the ciphertext in to. to must
       point to RSA_size(rsa) bytes of memory.

       padding denotes one of the following modes:

       RSA_PKCS1_PADDING
           PKCS #1 v1.5 padding. This currently is the most widely used mode.

       RSA_PKCS1_OAEP_PADDING
           EME-OAEP as defined in PKCS #1 v2.0 with SHA-1, MGF1 and an empty
           encoding parameter. This mode is recommended for all new applica-
           tions.

       RSA_SSLV23_PADDING
           PKCS #1 v1.5 padding with an SSL-specific modification that denotes
           that the server is SSL3 capable.

       RSA_NO_PADDING
           Raw RSA encryption. This mode should only be used to implement
           cryptographically sound padding modes in the application code.
           Encrypting user data directly with RSA is insecure.

       flen must be less than RSA_size(rsa) - 11 for the PKCS #1 v1.5 based
       padding modes, less than RSA_size(rsa) - 41 for RSA_PKCS1_OAEP_PADDING
       and exactly RSA_size(rsa) for RSA_NO_PADDING.  The random number gener-
       ator must be seeded prior to calling RSA_public_encrypt().

       RSA_private_decrypt() decrypts the flen bytes at from using the private
       key rsa and stores the plaintext in to. to must point to a memory sec-
       tion large enough to hold the decrypted data (which is smaller than
       RSA_size(rsa)). padding is the padding mode that was used to encrypt
       the data.

RETURN VALUES

       RSA_public_encrypt() returns the size of the encrypted data (i.e.,
       RSA_size(rsa)). RSA_private_decrypt() returns the size of the recovered
       plaintext.

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

WARNING

       Decryption failures in the RSA_PKCS1_PADDING mode leak information
       which can potentially be used to mount a Bleichenbacher padding oracle
       attack. This is an inherent weakness in the PKCS #1 v1.5 padding
       design. Prefer RSA_PKCS1_OAEP_PADDING.

CONFORMING TO

       SSL, PKCS #1 v2.0

SEE ALSO

       ERR_get_error(3), rand(3), rsa(3), RSA_size(3)

HISTORY

       The padding argument was added in SSLeay 0.8. RSA_NO_PADDING is avail-
       able since SSLeay 0.9.0, OAEP was added in OpenSSL 0.9.2b.

1.0.2t                            2019-09-10             RSA_public_encrypt(3)
See also RSA_private_decrypt(3)