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131 .IX Title "RSA_public_encrypt 3"
132 .TH RSA_public_encrypt 3 "2018-08-14" "1.0.2p" "OpenSSL"
133 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
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138 RSA_public_encrypt, RSA_private_decrypt \- RSA public key cryptography
140 .IX Header "SYNOPSIS"
142 \& #include <openssl/rsa.h>
144 \& int RSA_public_encrypt(int flen, const unsigned char *from,
145 \& unsigned char *to, RSA *rsa, int padding);
147 \& int RSA_private_decrypt(int flen, const unsigned char *from,
148 \& unsigned char *to, RSA *rsa, int padding);
151 .IX Header "DESCRIPTION"
152 \&\fIRSA_public_encrypt()\fR encrypts the \fBflen\fR bytes at \fBfrom\fR (usually a
153 session key) using the public key \fBrsa\fR and stores the ciphertext in
154 \&\fBto\fR. \fBto\fR must point to RSA_size(\fBrsa\fR) bytes of memory.
156 \&\fBpadding\fR denotes one of the following modes:
157 .IP "\s-1RSA_PKCS1_PADDING\s0" 4
158 .IX Item "RSA_PKCS1_PADDING"
159 \&\s-1PKCS\s0 #1 v1.5 padding. This currently is the most widely used mode.
160 .IP "\s-1RSA_PKCS1_OAEP_PADDING\s0" 4
161 .IX Item "RSA_PKCS1_OAEP_PADDING"
162 EME-OAEP as defined in \s-1PKCS\s0 #1 v2.0 with \s-1SHA\-1, MGF1\s0 and an empty
163 encoding parameter. This mode is recommended for all new applications.
164 .IP "\s-1RSA_SSLV23_PADDING\s0" 4
165 .IX Item "RSA_SSLV23_PADDING"
166 \&\s-1PKCS\s0 #1 v1.5 padding with an SSL-specific modification that denotes
167 that the server is \s-1SSL3\s0 capable.
168 .IP "\s-1RSA_NO_PADDING\s0" 4
169 .IX Item "RSA_NO_PADDING"
170 Raw \s-1RSA\s0 encryption. This mode should \fIonly\fR be used to implement
171 cryptographically sound padding modes in the application code.
172 Encrypting user data directly with \s-1RSA\s0 is insecure.
174 \&\fBflen\fR must be less than RSA_size(\fBrsa\fR) \- 11 for the \s-1PKCS\s0 #1 v1.5
175 based padding modes, less than RSA_size(\fBrsa\fR) \- 41 for
176 \&\s-1RSA_PKCS1_OAEP_PADDING\s0 and exactly RSA_size(\fBrsa\fR) for \s-1RSA_NO_PADDING.\s0
177 The random number generator must be seeded prior to calling
178 \&\fIRSA_public_encrypt()\fR.
180 \&\fIRSA_private_decrypt()\fR decrypts the \fBflen\fR bytes at \fBfrom\fR using the
181 private key \fBrsa\fR and stores the plaintext in \fBto\fR. \fBto\fR must point
182 to a memory section large enough to hold the decrypted data (which is
183 smaller than RSA_size(\fBrsa\fR)). \fBpadding\fR is the padding mode that
184 was used to encrypt the data.
186 .IX Header "RETURN VALUES"
187 \&\fIRSA_public_encrypt()\fR returns the size of the encrypted data (i.e.,
188 RSA_size(\fBrsa\fR)). \fIRSA_private_decrypt()\fR returns the size of the
191 On error, \-1 is returned; the error codes can be
192 obtained by \fIERR_get_error\fR\|(3).
195 Decryption failures in the \s-1RSA_PKCS1_PADDING\s0 mode leak information
196 which can potentially be used to mount a Bleichenbacher padding oracle
197 attack. This is an inherent weakness in the \s-1PKCS\s0 #1 v1.5 padding
198 design. Prefer \s-1RSA_PKCS1_OAEP_PADDING.\s0
200 .IX Header "CONFORMING TO"
201 \&\s-1SSL, PKCS\s0 #1 v2.0
203 .IX Header "SEE ALSO"
204 \&\fIERR_get_error\fR\|(3), \fIrand\fR\|(3), \fIrsa\fR\|(3),
205 \&\fIRSA_size\fR\|(3)
208 The \fBpadding\fR argument was added in SSLeay 0.8. \s-1RSA_NO_PADDING\s0 is
209 available since SSLeay 0.9.0, \s-1OAEP\s0 was added in OpenSSL 0.9.2b.