EVP_PKEY_ENCRYPT(3)

NAME
EVP_PKEY_encrypt_init_ex, EVP_PKEY_encrypt_init, EVP_PKEY_encrypt - encrypt using a public key algorithm

SYNOPSIS
 #include <openssl/evp.h>

 int EVP_PKEY_encrypt_init(EVP_PKEY_CTX *ctx);
 int EVP_PKEY_encrypt_init_ex(EVP_PKEY_CTX *ctx, const OSSL_PARAM params[]);
 int EVP_PKEY_encrypt(EVP_PKEY_CTX *ctx,
                      unsigned char *out, size_t *outlen,
                      const unsigned char *in, size_t inlen);

DESCRIPTION
The EVP_PKEY_encrypt_init() function initializes the public key algorithm context ctx for an encryption operation. A key must already be associated with ctx; this is normally done by creating it with EVP_PKEY_CTX_new(3) or EVP_PKEY_CTX_new_from_pkey(3).

The EVP_PKEY_encrypt_init_ex() function is the same as EVP_PKEY_encrypt_init() but additionally sets the algorithm-specific params.

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.

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

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

RETURN VALUES
EVP_PKEY_encrypt_init(), EVP_PKEY_encrypt_init_ex() 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.

EXAMPLES
Encrypt data using OAEP (for RSA keys). See also PEM_read_PUBKEY(3) or d2i_X509(3) for means to load a public key.

 #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 public key
  */
 ctx = EVP_PKEY_CTX_new_from_pkey(NULL, key, NULL);
 if (!ctx)
     /* Error occurred */
 if (EVP_PKEY_encrypt_init(ctx) <= 0)
     /* Error */
 if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_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 */

SEE ALSO
d2i_X509(3), EVP_PKEY_CTX_new(3), EVP_PKEY_decrypt(3), EVP_PKEY_sign(3), EVP_PKEY_verify(3), EVP_PKEY_verify_recover(3), EVP_PKEY_derive(3)

HISTORY
These functions were added in OpenSSL 1.0.0.

COPYRIGHT
Copyright 2006-2026 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (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>.