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EVP_PKEY_decrypt(3) OpenSSL EVP_PKEY_decrypt(3)
NAME
EVP_PKEY_decrypt_init, EVP_PKEY_decrypt - decrypt using a public key algorithm
SYNOPSIS
#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);
DESCRIPTION
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.
NOTES
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.
RETURN VALUES
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.
EXAMPLE
Decrypt data using OAEP (for RSA keys):
#include <openssl/evp.h>
#include <openssl/rsa.h>
EVP_PKEY_CTX *ctx;
unsigned char *out, *in;
size_t outlen, inlen;
EVP_PKEY *key;
/* NB: assumes key in, inlen are already set up
* and that key is an RSA private key
*/
ctx = EVP_PKEY_CTX_new(key);
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 */
SEE ALSO
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)
HISTORY
These functions were first added to OpenSSL 1.0.0.
1.0.2k 2017-01-26 EVP_PKEY_decrypt(3)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
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Under GNU General Public License
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