5 RSA_private_encrypt, RSA_public_decrypt - low-level signature operations
9 #include <openssl/rsa.h>
11 The following functions have been deprecated since OpenSSL 3.0, and can be
12 hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
13 see L<openssl_user_macros(7)>:
15 int RSA_private_encrypt(int flen, unsigned char *from,
16 unsigned char *to, RSA *rsa, int padding);
18 int RSA_public_decrypt(int flen, unsigned char *from,
19 unsigned char *to, RSA *rsa, int padding);
23 Both of the functions described on this page are deprecated.
24 Applications should instead use L<EVP_PKEY_sign_init_ex(3)>,
25 L<EVP_PKEY_sign(3)>, L<EVP_PKEY_verify_recover_init(3)>, and
26 L<EVP_PKEY_verify_recover(3)>.
28 These functions handle RSA signatures at a low-level.
30 RSA_private_encrypt() signs the B<flen> bytes at B<from> (usually a
31 message digest with an algorithm identifier) using the private key
32 B<rsa> and stores the signature in B<to>. B<to> must point to
33 B<RSA_size(rsa)> bytes of memory.
35 B<padding> denotes one of the following modes:
39 =item RSA_PKCS1_PADDING
41 PKCS #1 v1.5 padding. This function does not handle the
42 B<algorithmIdentifier> specified in PKCS #1. When generating or
43 verifying PKCS #1 signatures, L<RSA_sign(3)> and L<RSA_verify(3)> should be
48 Raw RSA signature. This mode should I<only> be used to implement
49 cryptographically sound padding modes in the application code.
50 Signing user data directly with RSA is insecure.
54 RSA_public_decrypt() recovers the message digest from the B<flen>
55 bytes long signature at B<from> using the signer's public key
56 B<rsa>. B<to> must point to a memory section large enough to hold the
57 message digest (which is smaller than B<RSA_size(rsa) -
58 11>). B<padding> is the padding mode that was used to sign the data.
62 RSA_private_encrypt() returns the size of the signature (i.e.,
63 RSA_size(rsa)). RSA_public_decrypt() returns the size of the
64 recovered message digest.
66 On error, -1 is returned; the error codes can be
67 obtained by L<ERR_get_error(3)>.
72 L<RSA_sign(3)>, L<RSA_verify(3)>,
73 L<EVP_PKEY_sign(3)>, L<EVP_PKEY_verify_recover(3)>
77 Both of these functions were deprecated in OpenSSL 3.0.
81 Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
83 Licensed under the Apache License 2.0 (the "License"). You may not use
84 this file except in compliance with the License. You can obtain a copy
85 in the file LICENSE in the source distribution or at
86 L<https://www.openssl.org/source/license.html>.