=pod

=head1 NAME

EVP_PKEY_encrypt_init, EVP_PKEY_encrypt - encrypt using a public key algorithm

=head1 SYNOPSIS

 #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);

=head1 DESCRIPTION

The EVP_PKEY_encrypt_init() function initializes a public key algorithm

context using key B<pkey> for an encryption operation.

The EVP_PKEY_encrypt() function performs a public key encryption operation

using B<ctx>. The data to be encrypted is specified using the B<in> and

B<inlen> parameters. If B<out> is B<NULL> then the maximum size of the output

buffer is written to the B<outlen> parameter. If B<out> is not B<NULL> then

before the call the B<outlen> parameter should contain the length of the

B<out> buffer, if the call is successful the encrypted data is written to

B<out> and the amount of data written to B<outlen>.

=head1 NOTES

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.

=head1 RETURN VALUES

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.

=head1 EXAMPLES

Encrypt data using OAEP (for RSA keys). See also L<PEM_read_PUBKEY(3)> or

L<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>

 EVP_PKEY_CTX *ctx;

 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 */

=head1 SEE ALSO

L<d2i_X509(3)>,

L<ENGINE_by_id(3)>,

L<EVP_PKEY_CTX_new(3)>,

L<EVP_PKEY_decrypt(3)>,

L<EVP_PKEY_sign(3)>,

L<EVP_PKEY_verify(3)>,

L<EVP_PKEY_verify_recover(3)>,

L<EVP_PKEY_derive(3)>

=head1 HISTORY

These functions were added in OpenSSL 1.0.0.

=head1 COPYRIGHT

Copyright 2006-2019 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

L<https://www.openssl.org/source/license.html>.

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