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137 .IX Title "RSA_blinding_on 3"
138 .TH RSA_blinding_on 3 "2009-07-19" "1.0.1n" "OpenSSL"
139 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
140 .\" way too many mistakes in technical documents.
141 .if n .ad l
142 .nh
143 .SH "NAME"
144 RSA_blinding_on, RSA_blinding_off \- protect the RSA operation from timing attacks
145 .SH "LIBRARY"
146 libcrypto, -lcrypto
147 .SH "SYNOPSIS"
148 .IX Header "SYNOPSIS"
149 .Vb 1
150 \& #include <openssl/rsa.h>
151 \&
152 \& int RSA_blinding_on(RSA *rsa, BN_CTX *ctx);
153 \&
154 \& void RSA_blinding_off(RSA *rsa);
155 .Ve
156 .SH "DESCRIPTION"
157 .IX Header "DESCRIPTION"
158 \&\s-1RSA\s0 is vulnerable to timing attacks. In a setup where attackers can
159 measure the time of \s-1RSA\s0 decryption or signature operations, blinding
160 must be used to protect the \s-1RSA\s0 operation from that attack.
161 .PP
162 \&\fIRSA_blinding_on()\fR turns blinding on for key \fBrsa\fR and generates a
163 random blinding factor. \fBctx\fR is \fB\s-1NULL\s0\fR or a pre-allocated and
164 initialized \fB\s-1BN_CTX\s0\fR. The random number generator must be seeded
165 prior to calling \fIRSA_blinding_on()\fR.
166 .PP
167 \&\fIRSA_blinding_off()\fR turns blinding off and frees the memory used for
168 the blinding factor.
169 .SH "RETURN VALUES"
170 .IX Header "RETURN VALUES"
171 \&\fIRSA_blinding_on()\fR returns 1 on success, and 0 if an error occurred.
172 .PP
173 \&\fIRSA_blinding_off()\fR returns no value.
174 .SH "SEE ALSO"
175 .IX Header "SEE ALSO"
176 \&\fIopenssl_rsa\fR\|(3), \fIopenssl_rand\fR\|(3)
177 .SH "HISTORY"
178 .IX Header "HISTORY"
179 \&\fIRSA_blinding_on()\fR and \fIRSA_blinding_off()\fR appeared in SSLeay 0.9.0.