PHP Sockets with SSL / TLS - no suitable shared cipher could be used

I am attempting to create a server and client using PHP Sockets with SSL / TLS. However, when sending data to the server, I receive the following error:

PHP Warning: stream_socket_accept(): SSL_R_NO_SHARED_CIPHER: no suitable shared cipher could be used. This could be because the server is missing an SSL certificate (local_cert context option) in server.php on line 32

I've looked at other examples and tried various changes to no avail. Any help could be much appreciated.

client.php

<?php

$host = '192.168.10.10';
$port = 8080;
$timeout = 30;
$cert = 'assets/cert.pem';

$context = stream_context_create(
    [ 'ssl'=> [ 'local_cert'=> $cert, "crypto_method" => STREAM_CRYPTO_METHOD_TLS_CLIENT ] ]
);

stream_context_set_option($context, 'ssl', 'allow_self_signed', true);
stream_context_set_option($context, 'ssl', 'verify_peer', false);
stream_context_set_option($context, 'ssl', 'verify_peer_name', false);

if ($socket = stream_socket_client( 'tls://'.$host.':'.$port, $errno, $errstr, 30, STREAM_CLIENT_CONNECT, $context) ) {
    $meta = stream_get_meta_data($socket);

    print_r( $meta );

    fwrite($socket, "Hello, World!\n");
    echo stream_socket_recvfrom($socket,8192);
    fclose($socket);
} else {
   echo "ERROR: $errno - $errstr\n";
}

server.php

<?php

// Set the ip and port we will listen on
$address = '192.168.10.10';
$port = 8080;

$cert = 'assets/cert.pem';

$context = stream_context_create();

stream_context_set_option($context, 'ssl', 'local_cert', $cert);
stream_context_set_option($context, 'ssl', 'crypto_method', STREAM_CRYPTO_METHOD_TLS_SERVER);

stream_context_set_option($context, 'ssl', 'allow_self_signed', true);
stream_context_set_option($context, 'ssl', 'verify_peer', false);
stream_context_set_option($context, 'ssl', 'verify_peer_name', false);

$server = stream_socket_server('tls://'.$address.':'.$port, $errno, $errstr, STREAM_SERVER_BIND|STREAM_SERVER_LISTEN, $context);

// Display server start time
echo "PHP Socket Server started at " . $address . " " . $port . ", at ". date( 'Y-m-d H:i:s' ) ."\n";

// loop and listen
while (true) {
    /* Accept incoming requests and handle them as child processes */
    $client = stream_socket_accept($server);

    $ip = stream_socket_get_name( $client, true );

    echo "New connection from " . $ip;

    stream_set_blocking($client, true); // block the connection until SSL is done
    stream_socket_enable_crypto($client, true, STREAM_CRYPTO_METHOD_TLS_SERVER);

    // Read the input from the client – 1024 bytes
    $input = fread($client, 1024);

    // unblock connection
    stream_set_blocking($client, false);

    // Strip all white spaces from input
    $output = preg_replace("[ \t\n\r]", "", $input) . "\0";

    $new = $input;

    // Display Date, IP and Msg received
    echo date( 'Y-m-d H:i:s' ) . " | " . $ip . ": \033[0;32m" . $input . "\033[0m" . PHP_EOL;

    fclose($client);
}

// Close the master sockets
socket_close($sock);

It turns out that the issue was related to OpenSSL and the transport streams available. The issue was resolved by:

• Updating OpenSSL to the latest version (1.0.2k, to support TLS v1.2)
• Recompiling PHP to enable tlsv1.2 transport stream

• Updating the code to use tlsv1.2:// as the protocol on both the server and the client, e.g.

  $server = stream_socket_server('tlsv1.2://'.$address.':'.$port, $errno, 
    $errstr, STREAM_SERVER_BIND|STREAM_SERVER_LISTEN, $context);
  

  and

  $socket = stream_socket_client( 'tlsv1.2://'.$host.':'.$port, $errno,
    $errstr, 30, STREAM_CLIENT_CONNECT, $context)
  

Once the transport stream was updated to TLSv1.2, there was no need for the cipher option, and the scripts successfully negotiated a TLS connection.