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=head1 NAME

RSA_blinding_on, RSA_blinding_off - protect the RSA operation from timing attacks

=head1 SYNOPSIS

 #include <openssl/rsa.h>

The following functions have been deprecated since OpenSSL 3.0, and can be
hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
see L<openssl_user_macros(7)>:

 int RSA_blinding_on(RSA *rsa, BN_CTX *ctx);

 void RSA_blinding_off(RSA *rsa);

=head1 DESCRIPTION

All of the functions described on this page are deprecated.

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 preallocated 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 HISTORY

All of these functions were deprecated in OpenSSL 3.0.

=head1 COPYRIGHT

Copyright 2000-2021 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>.

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