5 RSA_private_encrypt, RSA_public_decrypt - low level signature operations
9 #include <openssl/rsa.h>
11 int RSA_private_encrypt(int flen, unsigned char *from,
12 unsigned char *to, RSA *rsa, int padding);
14 int RSA_public_decrypt(int flen, unsigned char *from,
15 unsigned char *to, RSA *rsa, int padding);
19 These functions handle RSA signatures at a low level.
21 RSA_private_encrypt() signs the B<flen> bytes at B<from> (usually a
22 message digest with an algorithm identifier) using the private key
23 B<rsa> and stores the signature in B<to>. B<to> must point to
24 B<RSA_size(rsa)> bytes of memory.
26 B<padding> denotes one of the following modes:
30 =item RSA_PKCS1_PADDING
32 PKCS #1 v1.5 padding. This function does not handle the
33 B<algorithmIdentifier> specified in PKCS #1. When generating or
34 verifying PKCS #1 signatures, L<RSA_sign(3)> and L<RSA_verify(3)> should be
39 Raw RSA signature. This mode should I<only> be used to implement
40 cryptographically sound padding modes in the application code.
41 Signing user data directly with RSA is insecure.
45 RSA_public_decrypt() recovers the message digest from the B<flen>
46 bytes long signature at B<from> using the signer's public key
47 B<rsa>. B<to> must point to a memory section large enough to hold the
48 message digest (which is smaller than B<RSA_size(rsa) -
49 11>). B<padding> is the padding mode that was used to sign the data.
53 RSA_private_encrypt() returns the size of the signature (i.e.,
54 RSA_size(rsa)). RSA_public_decrypt() returns the size of the
55 recovered message digest.
57 On error, -1 is returned; the error codes can be
58 obtained by L<ERR_get_error(3)>.
63 L<RSA_sign(3)>, L<RSA_verify(3)>
67 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
69 Licensed under the OpenSSL license (the "License"). You may not use
70 this file except in compliance with the License. You can obtain a copy
71 in the file LICENSE in the source distribution or at
72 L<https://www.openssl.org/source/license.html>.