openssl/doc/crypto/RSA_public_encrypt.pod
Rich Salz 53934822ac Clean up "generic" intro pod files.
Files like dh.pod, etc., mostly duplicated the API-specific pod files.
Removed the duplicated content; that often mean the whole file could
be removed.  Some of the content about internals got moved into README
files in the source tree.  Some content (e.g., err.pod) got moved
into other pod pages.

Annotate generic pages, remove dup NAME

Reviewed-by: Richard Levitte <levitte@openssl.org>
2016-06-09 16:39:19 -04:00

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=pod
=head1 NAME
RSA_public_encrypt, RSA_private_decrypt - RSA public key cryptography
=head1 SYNOPSIS
#include <openssl/rsa.h>
int RSA_public_encrypt(int flen, unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
int RSA_private_decrypt(int flen, unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
=head1 DESCRIPTION
RSA_public_encrypt() encrypts the B<flen> bytes at B<from> (usually a
session key) using the public key B<rsa> and stores the ciphertext in
B<to>. B<to> must point to RSA_size(B<rsa>) bytes of memory.
B<padding> denotes one of the following modes:
=over 4
=item RSA_PKCS1_PADDING
PKCS #1 v1.5 padding. This currently is the most widely used mode.
=item RSA_PKCS1_OAEP_PADDING
EME-OAEP as defined in PKCS #1 v2.0 with SHA-1, MGF1 and an empty
encoding parameter. This mode is recommended for all new applications.
=item RSA_SSLV23_PADDING
PKCS #1 v1.5 padding with an SSL-specific modification that denotes
that the server is SSL3 capable.
=item RSA_NO_PADDING
Raw RSA encryption. This mode should I<only> be used to implement
cryptographically sound padding modes in the application code.
Encrypting user data directly with RSA is insecure.
=back
B<flen> must be less than RSA_size(B<rsa>) - 11 for the PKCS #1 v1.5
based padding modes, less than RSA_size(B<rsa>) - 41 for
RSA_PKCS1_OAEP_PADDING and exactly RSA_size(B<rsa>) for RSA_NO_PADDING.
The random number generator must be seeded prior to calling
RSA_public_encrypt().
RSA_private_decrypt() decrypts the B<flen> bytes at B<from> using the
private key B<rsa> and stores the plaintext in B<to>. B<to> must point
to a memory section large enough to hold the decrypted data (which is
smaller than RSA_size(B<rsa>)). B<padding> is the padding mode that
was used to encrypt the data.
=head1 RETURN VALUES
RSA_public_encrypt() returns the size of the encrypted data (i.e.,
RSA_size(B<rsa>)). RSA_private_decrypt() returns the size of the
recovered plaintext.
On error, -1 is returned; the error codes can be
obtained by L<ERR_get_error(3)>.
=head1 CONFORMING TO
SSL, PKCS #1 v2.0
=head1 SEE ALSO
L<ERR_get_error(3)>, L<rand(3)>,
L<RSA_size(3)>
=head1 COPYRIGHT
Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.
=cut