5 RSA_public_encrypt, RSA_private_decrypt - RSA public key cryptography
9 #include <openssl/rsa.h>
11 int RSA_public_encrypt(int flen, unsigned char *from,
12 unsigned char *to, RSA *rsa, int padding);
14 int RSA_private_decrypt(int flen, unsigned char *from,
15 unsigned char *to, RSA *rsa, int padding);
19 RSA_public_encrypt() encrypts the B<flen> bytes at B<from> (usually a
20 session key) using the public key B<rsa> and stores the ciphertext in
21 B<to>. B<to> must point to RSA_size(B<rsa>) bytes of memory.
23 B<padding> denotes one of the following modes:
27 =item RSA_PKCS1_PADDING
29 PKCS #1 v1.5 padding. This currently is the most widely used mode.
31 =item RSA_PKCS1_OAEP_PADDING
33 EME-OAEP as defined in PKCS #1 v2.0 with SHA-1, MGF1 and an empty
34 encoding parameter. This mode is recommended for all new applications.
36 =item RSA_SSLV23_PADDING
38 PKCS #1 v1.5 padding with an SSL-specific modification that denotes
39 that the server is SSL3 capable.
43 Raw RSA encryption. This mode should I<only> be used to implement
44 cryptographically sound padding modes in the application code.
45 Encrypting user data directly with RSA is insecure.
49 B<flen> must be less than RSA_size(B<rsa>) - 11 for the PKCS #1 v1.5
50 based padding modes, less than RSA_size(B<rsa>) - 41 for
51 RSA_PKCS1_OAEP_PADDING and exactly RSA_size(B<rsa>) for RSA_NO_PADDING.
52 The random number generator must be seeded prior to calling
55 RSA_private_decrypt() decrypts the B<flen> bytes at B<from> using the
56 private key B<rsa> and stores the plaintext in B<to>. B<to> must point
57 to a memory section large enough to hold the decrypted data (which is
58 smaller than RSA_size(B<rsa>)). B<padding> is the padding mode that
59 was used to encrypt the data.
63 RSA_public_encrypt() returns the size of the encrypted data (i.e.,
64 RSA_size(B<rsa>)). RSA_private_decrypt() returns the size of the
67 On error, -1 is returned; the error codes can be
68 obtained by L<ERR_get_error(3)>.
72 Decryption failures in the RSA_PKCS1_PADDING mode leak information
73 which can potentially be used to mount a Bleichenbacher padding oracle
74 attack. This is an inherent weakness in the PKCS #1 v1.5 padding
75 design. Prefer RSA_PKCS1_OAEP_PADDING.
83 L<ERR_get_error(3)>, L<RAND_bytes(3)>,
88 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
90 Licensed under the OpenSSL license (the "License"). You may not use
91 this file except in compliance with the License. You can obtain a copy
92 in the file LICENSE in the source distribution or at
93 L<https://www.openssl.org/source/license.html>.