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 a public key algorithm context using key
       pkey for an encryption operation.

       The EVP_PKEY_encrypt_init_ex() function initializes a public key algorithm context using
       key pkey for an encryption operation and 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. 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_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), ENGINE_by_id(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 2006-2022 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>.