=pod =head1 NAME RSA_private_encrypt, RSA_public_decrypt - low level signature operations =head1 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); =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 Apache License 2.0 (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