NAME

       EVP_PKEY_set1_encoded_public_key, EVP_PKEY_get1_encoded_public_key,
       EVP_PKEY_set1_tls_encodedpoint, EVP_PKEY_get1_tls_encodedpoint - functions to set and get
       public key data within an EVP_PKEY

SYNOPSIS

        #include <openssl/evp.h>

        int EVP_PKEY_set1_encoded_public_key(EVP_PKEY *pkey,
                                             const unsigned char *pub, size_t publen);

        size_t EVP_PKEY_get1_encoded_public_key(EVP_PKEY *pkey, unsigned char **ppub);

       The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely
       by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

        int EVP_PKEY_set1_tls_encodedpoint(EVP_PKEY *pkey,
                                           const unsigned char *pt, size_t ptlen);

        size_t EVP_PKEY_get1_tls_encodedpoint(EVP_PKEY *pkey, unsigned char **ppt);

DESCRIPTION

       EVP_PKEY_set1_encoded_public_key() can be used to set the public key value within an
       existing EVP_PKEY object. For the built-in OpenSSL algorithms this currently only works
       for those that support key exchange. Parameters are not set as part of this operation, so
       typically an application will create an EVP_PKEY first, set the parameters on it, and then
       call this function.  For example setting the parameters might be done using
       EVP_PKEY_copy_parameters(3).

       The format for the encoded public key will depend on the algorithm in use. For DH it
       should be encoded as a positive integer in big-endian form. For EC is should be a point
       conforming to Sec. 2.3.4 of the SECG SEC 1 ("Elliptic Curve Cryptography") standard. For
       X25519 and X448 it should be encoded in a format as defined by RFC7748.

       The key to be updated is supplied in pkey. The buffer containing the encoded key is
       pointed to be pub. The length of the buffer is supplied in publen.

       EVP_PKEY_get1_encoded_public_key() does the equivalent operation except that the encoded
       public key is returned to the application. The key containing the public key data is
       supplied in pkey. A buffer containing the encoded key will be allocated and stored in
       *ppub. The length of the encoded public key is returned by the function. The application
       is responsible for freeing the allocated buffer.

       The macro EVP_PKEY_set1_tls_encodedpoint() is deprecated and simply calls
       EVP_PKEY_set1_encoded_public_key() with all the same arguments. New applications should
       use EVP_PKEY_set1_encoded_public_key() instead.

       The macro EVP_PKEY_get1_tls_encodedpoint() is deprecated and simply calls
       EVP_PKEY_get1_encoded_public_key() with all the same arguments. New applications should
       use EVP_PKEY_get1_encoded_public_key() instead.

RETURN VALUES

       EVP_PKEY_set1_encoded_public_key() returns 1 for success and 0 or a negative value for
       failure.

       EVP_PKEY_get1_encoded_public_key() returns the length of the encoded key or 0 for failure.

EXAMPLES

       See EVP_PKEY_derive_init(3) and EVP_PKEY_derive(3) for information about performing a key
       exchange operation.

   Set up a peer's EVP_PKEY ready for a key exchange operation
        #include <openssl/evp.h>

        int exchange(EVP_PKEY *ourkey, unsigned char *peer_pub, size_t peer_pub_len)
        {
            EVP_PKEY *peerkey = EVP_PKEY_new();

            if (peerkey == NULL || EVP_PKEY_copy_parameters(peerkey, ourkey) <= 0)
                return 0;

            if (EVP_PKEY_set1_encoded_public_key(peerkey, peer_pub,
                                                 peer_pub_len) <= 0)
                return 0;

            /* Do the key exchange here */

            EVP_PKEY_free(peerkey);

            return 1;
        }

   Get an encoded public key to send to a peer
        #include <openssl/evp.h>

        int get_encoded_pub_key(EVP_PKEY *ourkey)
        {
            unsigned char *pubkey;
            size_t pubkey_len;

           pubkey_len = EVP_PKEY_get1_encoded_public_key(ourkey, &pubkey);
           if (pubkey_len == 0)
               return 0;

           /*
            * Send the encoded public key stored in the buffer at "pubkey" and of
            * length pubkey_len, to the peer.
            */

           OPENSSL_free(pubkey);
           return 1;
        }

SEE ALSO

       EVP_PKEY_new(3), EVP_PKEY_copy_parameters(3), EVP_PKEY_derive_init(3), EVP_PKEY_derive(3),
       EVP_PKEY-DH(7), EVP_PKEY-EC(7), EVP_PKEY-X25519(7), EVP_PKEY-X448(7)

HISTORY

       EVP_PKEY_set1_encoded_public_key() and EVP_PKEY_get1_encoded_public_key() were added in
       OpenSSL 3.0.

       EVP_PKEY_set1_tls_encodedpoint() and EVP_PKEY_get1_tls_encodedpoint() were deprecated in
       OpenSSL 3.0.

COPYRIGHT

       Copyright 2020-2021 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>.