=pod =head1 NAME RSA_private_encrypt, RSA_public_decrypt - low level signature operations =head1 SYNOPSIS #include int RSA_private_encrypt(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding); int RSA_public_decrypt(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding); =head1 DESCRIPTION These functions handle RSA signatures at a low level. RSA_private_encrypt() signs the B bytes at B (usually a message digest with an algorithm identifier) using the private key B and stores the signature in B. B must point to B bytes of memory. B denotes one of the following modes: =over 4 =item RSA_PKCS1_PADDING PKCS #1 v1.5 padding. This function does not handle the B specified in PKCS #1. When generating or verifying PKCS #1 signatures, L and L should be used. =item RSA_NO_PADDING Raw RSA signature. This mode should I be used to implement cryptographically sound padding modes in the application code. Signing user data directly with RSA is insecure. =back RSA_public_decrypt() recovers the message digest from the B bytes long signature at B using the signer's public key B. B must point to a memory section large enough to hold the message digest (which is smaller than B). B is the padding mode that was used to sign the data. =head1 RETURN VALUES RSA_private_encrypt() returns the size of the signature (i.e., RSA_size(rsa)). RSA_public_decrypt() returns the size of the recovered message digest. On error, -1 is returned; the error codes can be obtained by L. =head1 SEE ALSO L, L, L =head1 COPYRIGHT Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved. Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at L. =cut