/usr/man/cat.3/SSL_CTX_use_psk_identity_hint.3

SSL_CTX_use_psk_identity_hint(3OpenSSSSL_CTX_use_psk_identity_hint(3)

NAME

     SSL_CTX_use_psk_identity_hint, SSL_use_psk_identity_hint,
     SSL_CTX_set_psk_server_callback, SSL_set_psk_server_callback
     - set PSK identity hint to use

SYNOPSIS

      #include <openssl/ssl.h>

      int SSL_CTX_use_psk_identity_hint(SSL_CTX *ctx, const char *hint);
      int SSL_use_psk_identity_hint(SSL *ssl, const char *hint);

      void SSL_CTX_set_psk_server_callback(SSL_CTX *ctx,
             unsigned int (*callback)(SSL *ssl, const char *identity,
             unsigned char *psk, int max_psk_len));
      void SSL_set_psk_server_callback(SSL *ssl,
             unsigned int (*callback)(SSL *ssl, const char *identity,
             unsigned char *psk, int max_psk_len));

DESCRIPTION

     SSL_CTX_use_psk_identity_hint() sets the given
     NULL-terminated PSK identity hint hint to SSL context object
     ctx. SSL_use_psk_identity_hint() sets the given
     NULL-terminated PSK identity hint hint to SSL connection
     object ssl. If hint is NULL the current hint from ctx or ssl
     is deleted.

     In the case where PSK identity hint is NULL, the server does
     not send the ServerKeyExchange message to the client.

     A server application must provide a callback function which
     is called when the server receives the ClientKeyExchange
     message from the client. The purpose of the callback
     function is to validate the received PSK identity and to
     fetch the pre-shared key used during the connection setup
     phase. The callback is set using functions
     SSL_CTX_set_psk_server_callback() or
     SSL_set_psk_server_callback(). The callback function is
     given the connection in parameter ssl, NULL-terminated PSK
     identity sent by the client in parameter identity, and a
     buffer psk of length max_psk_len bytes where the pre-shared
     key is to be stored.

RETURN VALUES

     SSL_CTX_use_psk_identity_hint() and
     SSL_use_psk_identity_hint() return 1 on success, 0
     otherwise.

     Return values from the server callback are interpreted as
     follows:

     0   PSK identity was not found. An "unknown_psk_identity"
         alert message will be sent and the connection setup

1.0.2t               Last change: 2019-09-10                    1

SSL_CTX_use_psk_identity_hint(3OpenSSSSL_CTX_use_psk_identity_hint(3)

         fails.

     >0  PSK identity was found and the server callback has
         provided the PSK successfully in parameter psk. Return
         value is the length of psk in bytes. It is an error to
         return a value greater than max_psk_len.

         If the PSK identity was not found but the callback
         instructs the protocol to continue anyway, the callback
         must provide some random data to psk and return the
         length of the random data, so the connection will fail
         with decryption_error before it will be finished
         completely.

1.0.2t               Last change: 2019-09-10                    2

See also SSL_CTX_set_psk_server_callback(3)
See also SSL_set_psk_server_callback(3)
See also SSL_use_psk_identity_hint(3)