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<li><a href="#NAME">NAME</a></li>
<li><a href="#SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#DESCRIPTION">DESCRIPTION</a></li>
<li><a href="#NOTES">NOTES</a></li>
<li><a href="#RETURN-VALUES">RETURN VALUES</a></li>
<li><a href="#EXAMPLES">EXAMPLES</a></li>
<li><a href="#SEE-ALSO">SEE ALSO</a></li>
<li><a href="#HISTORY">HISTORY</a></li>
<li><a href="#COPYRIGHT">COPYRIGHT</a></li>
</ul>
<h1 id="NAME">NAME</h1>
<p>EVP_PKEY_decrypt_init, EVP_PKEY_decrypt - decrypt using a public key algorithm</p>
<h1 id="SYNOPSIS">SYNOPSIS</h1>
<pre><code> #include <openssl/evp.h>
int EVP_PKEY_decrypt_init(EVP_PKEY_CTX *ctx);
int EVP_PKEY_decrypt(EVP_PKEY_CTX *ctx,
unsigned char *out, size_t *outlen,
const unsigned char *in, size_t inlen);</code></pre>
<h1 id="DESCRIPTION">DESCRIPTION</h1>
<p>The EVP_PKEY_decrypt_init() function initializes a public key algorithm context using key <b>pkey</b> for a decryption operation.</p>
<p>The EVP_PKEY_decrypt() function performs a public key decryption operation using <b>ctx</b>. The data to be decrypted is specified using the <b>in</b> and <b>inlen</b> parameters. If <b>out</b> is <b>NULL</b> then the maximum size of the output buffer is written to the <b>outlen</b> parameter. If <b>out</b> is not <b>NULL</b> then before the call the <b>outlen</b> parameter should contain the length of the <b>out</b> buffer, if the call is successful the decrypted data is written to <b>out</b> and the amount of data written to <b>outlen</b>.</p>
<h1 id="NOTES">NOTES</h1>
<p>After the call to EVP_PKEY_decrypt_init() algorithm specific control operations can be performed to set any appropriate parameters for the operation.</p>
<p>The function EVP_PKEY_decrypt() can be called more than once on the same context if several operations are performed using the same parameters.</p>
<h1 id="RETURN-VALUES">RETURN VALUES</h1>
<p>EVP_PKEY_decrypt_init() and EVP_PKEY_decrypt() return 1 for success and 0 or a negative value for failure. In particular a return value of -2 indicates the operation is not supported by the public key algorithm.</p>
<h1 id="EXAMPLES">EXAMPLES</h1>
<p>Decrypt data using OAEP (for RSA keys):</p>
<pre><code> #include <openssl/evp.h>
#include <openssl/rsa.h>
EVP_PKEY_CTX *ctx;
ENGINE *eng;
unsigned char *out, *in;
size_t outlen, inlen;
EVP_PKEY *key;
/*
* NB: assumes key, eng, in, inlen are already set up
* and that key is an RSA private key
*/
ctx = EVP_PKEY_CTX_new(key, eng);
if (!ctx)
/* Error occurred */
if (EVP_PKEY_decrypt_init(ctx) <= 0)
/* Error */
if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_OAEP_PADDING) <= 0)
/* Error */
/* Determine buffer length */
if (EVP_PKEY_decrypt(ctx, NULL, &outlen, in, inlen) <= 0)
/* Error */
out = OPENSSL_malloc(outlen);
if (!out)
/* malloc failure */
if (EVP_PKEY_decrypt(ctx, out, &outlen, in, inlen) <= 0)
/* Error */
/* Decrypted data is outlen bytes written to buffer out */</code></pre>
<h1 id="SEE-ALSO">SEE ALSO</h1>
<p><a href="../man3/EVP_PKEY_CTX_new.html">EVP_PKEY_CTX_new(3)</a>, <a href="../man3/EVP_PKEY_encrypt.html">EVP_PKEY_encrypt(3)</a>, <a href="../man3/EVP_PKEY_sign.html">EVP_PKEY_sign(3)</a>, <a href="../man3/EVP_PKEY_verify.html">EVP_PKEY_verify(3)</a>, <a href="../man3/EVP_PKEY_verify_recover.html">EVP_PKEY_verify_recover(3)</a>, <a href="../man3/EVP_PKEY_derive.html">EVP_PKEY_derive(3)</a></p>
<h1 id="HISTORY">HISTORY</h1>
<p>These functions were added in OpenSSL 1.0.0.</p>
<h1 id="COPYRIGHT">COPYRIGHT</h1>
<p>Copyright 2006-2019 The OpenSSL Project Authors. All Rights Reserved.</p>
<p>Licensed under the OpenSSL license (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 <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>
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