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 Title "RSA_blinding_on 3" 
 RSA_blinding_on 3 2026-04-07 3.5.6 OpenSSL
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 NAME
RSA_blinding_on, RSA_blinding_off - protect the RSA operation from timing attacks

 SYNOPSIS
 Header "SYNOPSIS" .Vb 1
 #include <openssl/rsa.h>
.Ve


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


.Vb 1
 int RSA_blinding_on(RSA *rsa, BN_CTX *ctx);
\&
 void RSA_blinding_off(RSA *rsa);
.Ve

 DESCRIPTION
 Header "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.


\fBRSA_blinding_on() turns blinding on for key rsa and generates a
random blinding factor. ctx is NULL or a preallocated and
initialized BN_CTX.


\fBRSA_blinding_off() turns blinding off and frees the memory used for
the blinding factor.

 "RETURN VALUES"
 Header "RETURN VALUES" \fBRSA_blinding_on() returns 1 on success, and 0 if an error occurred.


\fBRSA_blinding_off() returns no value.

 HISTORY
 Header "HISTORY" All of these functions were deprecated in OpenSSL 3.0.

 COPYRIGHT
 Header "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
<https://www.openssl.org/source/license.html>.