EVP_PKEY_encrypt_init, EVP_PKEY_encrypt — encrypt using a public key algorithm


#include  <openssl/evp.h>
int EVP_PKEY_encrypt_init(EVP_PKEY_CTX *ctx);
int EVP_PKEY_encrypt(EVP_PKEY_CTX *ctx,
                       unsigned char *out, size_t *outlen,
                       const unsigned char *in, size_t inlen);


The EVP_PKEY_encrypt_init() function initializes a public key algorithm context using key pkey for an encryption operation.

The EVP_PKEY_encrypt() function performs a public key encryption operation using ctx. The data to be encrypted 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 encrypted data is written to out and the amount of data written to outlen.


After the call to EVP_PKEY_encrypt_init() algorithm specific control operations can be performed to set any appropriate parameters for the operation.

The function EVP_PKEY_encrypt() can be called more than once on the same context if several operations are performed using the same parameters.


EVP_PKEY_encrypt_init() and EVP_PKEY_encrypt() 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.


Encrypt data using OAEP (for RSA keys). See also PEM_read_PUBKEY(3) or d2i_X509(3) for means to load a public key. You may also simply set 'eng = NULL;' to start with the default OpenSSL RSA implementation:

#include <openssl/evp.h>
#include <openssl/rsa.h>
#include <openssl/engine.h>

ENGINE *eng;
unsigned char *out, *in;
size_t outlen, inlen;
EVP_PKEY *key;
/* NB: assumes eng, key, in, inlen are already set up,
 * and that key is an RSA public key
ctx = EVP_PKEY_CTX_new(key,eng);
if (!ctx)
       /* Error occurred */
if (EVP_PKEY_encrypt_init(ctx) <= 0)
       /* Error */
if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_OAEP_PADDING) <= 0)
       /* Error */

/* Determine buffer length */
if (EVP_PKEY_encrypt(ctx, NULL, &outlen, in, inlen) <= 0)
       /* Error */

out = OPENSSL_malloc(outlen);

if (!out)
       /* malloc failure */

if (EVP_PKEY_encrypt(ctx, out, &outlen, in, inlen) <= 0)
       /* Error */

/* Encrypted data is outlen bytes written to buffer out */


These functions were first added to OpenSSL 1.0.0.