---
name: "libressl-RSA_blinding_on"
section: "3"
platform: "linux"
package: "libressl"
version: "4.4.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/libressl-RSA_blinding_on"
---

# libressl-RSA\_blinding\_on(3)

protect the RSA operation from timing attacks

## NAME

**RSA\_blinding\_on**, **RSA\_blinding\_off** – protect the RSA operation from timing attacks

## SYNOPSIS

Crypto Library (libcrypto, -lcrypto)

**#include \<openssl/rsa.h\>**

*int*\

**RSA\_blinding\_on**(*RSA \*rsa*, *BN\_CTX \*ctx*);

*void*\

**RSA\_blinding\_off**(*RSA \*rsa*);

## 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 *rsa* and generates a random blinding factor. *ctx* is NULL or a pre-allocated and initialized *BN\_CTX*.

**RSA\_blinding\_off**() turns blinding off and frees the memory used for the blinding factor.

## RETURN VALUES

**RSA\_blinding\_on**() returns 1 on success, and 0 if an error occurred.

## SEE ALSO

RSA\_new(3)

## HISTORY

**RSA\_blinding\_on**() and **RSA\_blinding\_off**() first appeared in SSLeay 0.9.0 and have been available since OpenBSD 2.4.