1=pod 2 3=head1 NAME 4 5RSA_private_encrypt, RSA_public_decrypt - low-level signature operations 6 7=head1 SYNOPSIS 8 9 #include <openssl/rsa.h> 10 11The following functions have been deprecated since OpenSSL 3.0, and can be 12hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value, 13see L<openssl_user_macros(7)>: 14 15 int RSA_private_encrypt(int flen, unsigned char *from, 16 unsigned char *to, RSA *rsa, int padding); 17 18 int RSA_public_decrypt(int flen, unsigned char *from, 19 unsigned char *to, RSA *rsa, int padding); 20 21=head1 DESCRIPTION 22 23Both of the functions described on this page are deprecated. 24Applications should instead use L<EVP_PKEY_sign_init_ex(3)>, 25L<EVP_PKEY_sign(3)>, L<EVP_PKEY_verify_recover_init(3)>, and 26L<EVP_PKEY_verify_recover(3)>. 27 28These functions handle RSA signatures at a low-level. 29 30RSA_private_encrypt() signs the B<flen> bytes at B<from> (usually a 31message digest with an algorithm identifier) using the private key 32B<rsa> and stores the signature in B<to>. B<to> must point to 33B<RSA_size(rsa)> bytes of memory. 34 35B<padding> denotes one of the following modes: 36 37=over 4 38 39=item RSA_PKCS1_PADDING 40 41PKCS #1 v1.5 padding. This function does not handle the 42B<algorithmIdentifier> specified in PKCS #1. When generating or 43verifying PKCS #1 signatures, L<RSA_sign(3)> and L<RSA_verify(3)> should be 44used. 45 46=item RSA_NO_PADDING 47 48Raw RSA signature. This mode should I<only> be used to implement 49cryptographically sound padding modes in the application code. 50Signing user data directly with RSA is insecure. 51 52=back 53 54RSA_public_decrypt() recovers the message digest from the B<flen> 55bytes long signature at B<from> using the signer's public key 56B<rsa>. B<to> must point to a memory section large enough to hold the 57message digest (which is smaller than B<RSA_size(rsa) - 5811>). B<padding> is the padding mode that was used to sign the data. 59 60=head1 RETURN VALUES 61 62RSA_private_encrypt() returns the size of the signature (i.e., 63RSA_size(rsa)). RSA_public_decrypt() returns the size of the 64recovered message digest. 65 66On error, -1 is returned; the error codes can be 67obtained by L<ERR_get_error(3)>. 68 69=head1 SEE ALSO 70 71L<ERR_get_error(3)>, 72L<RSA_sign(3)>, L<RSA_verify(3)>, 73L<EVP_PKEY_sign(3)>, L<EVP_PKEY_verify_recover(3)> 74 75=head1 HISTORY 76 77Both of these functions were deprecated in OpenSSL 3.0. 78 79=head1 COPYRIGHT 80 81Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved. 82 83Licensed under the Apache License 2.0 (the "License"). You may not use 84this file except in compliance with the License. You can obtain a copy 85in the file LICENSE in the source distribution or at 86L<https://www.openssl.org/source/license.html>. 87 88=cut 89