openssl/doc/man3/RSA_blinding_on.pod
Dr. Matthias St. Pierre 262c00882a man: clarify the 'random number generator must be seeded' requirement
The manual pages require for some API functions that the 'random number
generator must be seeded' before calling the function.  Initially, this
was meant literally, i.e. the OpenSSL CSPRNG had to be seeded manually
before calling these functions.

Since version 1.1.1, the CSPRNG is seeded automatically on first use,
so it's not the responsibility of the programmer anymore.  Still, he
needs to be aware that the seeding might fail.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/9257)
2019-06-27 14:39:07 +02:00

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=pod
=head1 NAME
RSA_blinding_on, RSA_blinding_off - protect the RSA operation from timing attacks
=head1 SYNOPSIS
#include <openssl/rsa.h>
int RSA_blinding_on(RSA *rsa, BN_CTX *ctx);
void RSA_blinding_off(RSA *rsa);
=head1 DESCRIPTION
RSA is vulnerable to timing attacks. In a setup where attackers can
measure the time of RSA decryption or signature operations, blinding
must be used to protect the RSA operation from that attack.
RSA_blinding_on() turns blinding on for key B<rsa> and generates a
random blinding factor. B<ctx> is B<NULL> or a pre-allocated and
initialized B<BN_CTX>.
RSA_blinding_off() turns blinding off and frees the memory used for
the blinding factor.
=head1 RETURN VALUES
RSA_blinding_on() returns 1 on success, and 0 if an error occurred.
RSA_blinding_off() returns no value.
=head1 COPYRIGHT
Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (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