1=pod 2 3=head1 NAME 4 5RSA_public_encrypt, RSA_private_decrypt - RSA public key cryptography 6 7=head1 SYNOPSIS 8 9 #include <openssl/rsa.h> 10 11 int RSA_public_encrypt(int flen, unsigned char *from, 12 unsigned char *to, RSA *rsa, int padding); 13 14 int RSA_private_decrypt(int flen, unsigned char *from, 15 unsigned char *to, RSA *rsa, int padding); 16 17=head1 DESCRIPTION 18 19RSA_public_encrypt() encrypts the B<flen> bytes at B<from> (usually a 20session key) using the public key B<rsa> and stores the ciphertext in 21B<to>. B<to> must point to RSA_size(B<rsa>) bytes of memory. 22 23B<padding> denotes one of the following modes: 24 25=over 4 26 27=item RSA_PKCS1_PADDING 28 29PKCS #1 v1.5 padding. This currently is the most widely used mode. 30 31=item RSA_PKCS1_OAEP_PADDING 32 33EME-OAEP as defined in PKCS #1 v2.0 with SHA-1, MGF1 and an empty 34encoding parameter. This mode is recommended for all new applications. 35 36=item RSA_SSLV23_PADDING 37 38PKCS #1 v1.5 padding with an SSL-specific modification that denotes 39that the server is SSL3 capable. 40 41=item RSA_NO_PADDING 42 43Raw RSA encryption. This mode should I<only> be used to implement 44cryptographically sound padding modes in the application code. 45Encrypting user data directly with RSA is insecure. 46 47=back 48 49B<flen> must be less than RSA_size(B<rsa>) - 11 for the PKCS #1 v1.5 50based padding modes, less than RSA_size(B<rsa>) - 41 for 51RSA_PKCS1_OAEP_PADDING and exactly RSA_size(B<rsa>) for RSA_NO_PADDING. 52The random number generator must be seeded prior to calling 53RSA_public_encrypt(). 54 55RSA_private_decrypt() decrypts the B<flen> bytes at B<from> using the 56private key B<rsa> and stores the plaintext in B<to>. B<to> must point 57to a memory section large enough to hold the decrypted data (which is 58smaller than RSA_size(B<rsa>)). B<padding> is the padding mode that 59was used to encrypt the data. 60 61=head1 RETURN VALUES 62 63RSA_public_encrypt() returns the size of the encrypted data (i.e., 64RSA_size(B<rsa>)). RSA_private_decrypt() returns the size of the 65recovered plaintext. 66 67On error, -1 is returned; the error codes can be 68obtained by L<ERR_get_error(3)>. 69 70=head1 WARNING 71 72Decryption failures in the RSA_PKCS1_PADDING mode leak information 73which can potentially be used to mount a Bleichenbacher padding oracle 74attack. This is an inherent weakness in the PKCS #1 v1.5 padding 75design. Prefer RSA_PKCS1_OAEP_PADDING. 76 77=head1 CONFORMING TO 78 79SSL, PKCS #1 v2.0 80 81=head1 SEE ALSO 82 83L<ERR_get_error(3)>, L<RAND_bytes(3)>, 84L<RSA_size(3)> 85 86=head1 COPYRIGHT 87 88Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved. 89 90Licensed under the OpenSSL license (the "License"). You may not use 91this file except in compliance with the License. You can obtain a copy 92in the file LICENSE in the source distribution or at 93L<https://www.openssl.org/source/license.html>. 94 95=cut 96