EVP_PKEY_decrypt_init, EVP_PKEY_decrypt - decrypt using a public key algorithm
#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);
The
EVP_PKEY_decrypt_init() function initializes a public key algorithm
context using key
pkey for a decryption operation.
The
EVP_PKEY_decrypt() function performs a public key decryption
operation using
ctx. The data to be decrypted is specified using the
in and
inlen parameters. If
out is
NULL then the
maximum size of the output buffer is written to the
outlen parameter.
If
out is not
NULL then before the call the
outlen
parameter should contain the length of the
out buffer, if the call is
successful the decrypted data is written to
out and the amount of data
written to
outlen.
After the call to
EVP_PKEY_decrypt_init() algorithm specific control
operations can be performed to set any appropriate parameters for the
operation.
The function
EVP_PKEY_decrypt() can be called more than once on the same
context if several operations are performed using the same parameters.
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.
Decrypt data using OAEP (for RSA keys):
#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 */
EVP_PKEY_CTX_new(3),
EVP_PKEY_encrypt(3),
EVP_PKEY_sign(3),
EVP_PKEY_verify(3),
EVP_PKEY_verify_recover(3),
EVP_PKEY_derive(3)
These functions were first added to OpenSSL 1.0.0.
Copyright 2006-2018 The OpenSSL Project Authors. All Rights Reserved.
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
<https://www.openssl.org/source/license.html>.