clearkey-messagehandler.js

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// Expect utf8decoder and utf8decoder to be TextEncoder('utf-8') and TextDecoder('utf-8') respectively

function MessageHandler( keysystem, content ) {

    this._keysystem = keysystem;

    this._content = content;

    this.messagehandler = MessageHandler.prototype.messagehandler.bind( this );

    this.servercertificate = undefined;

MessageHandler.prototype.messagehandler = function messagehandler( messageType, message )

    if ( messageType === 'license-request' )

        var request = fromUtf8( message );

        var keys = request.kids.map( function( kid ) {

            var key;

            for( var i=0; i < this._content.keys.length; ++i )

                if ( base64urlEncode( this._content.keys[ i ].kid ) === kid )

                    key = base64urlEncode( this._content.keys[ i ].key );

                    break;

            return { kty: 'oct', kid: kid, k: key };

        }.bind( this ) );

        return Promise.resolve( toUtf8( { keys: keys } ) );

    else if ( messageType === 'license-release' )

        var release = fromUtf8( message );

        // TODO: Check the license release message here

        return Promise.resolve( toUtf8( { kids: release.kids } ) );

    throw new TypeError( 'Unsupported message type for ClearKey' );

};

MessageHandler.prototype.createJWKSet = function createJWKSet(keyId, key) {

    var jwkSet = '{"keys":[';

    for (var i = 0; i < arguments.length; i++) {

        if (i != 0)

            jwkSet += ',';

        jwkSet += arguments[i];

    jwkSet += ']}';

    return jwkSet;

};

MessageHandler.prototype.createJWK = function createJWK(keyId, key) {

    var jwk = '{"kty":"oct","alg":"A128KW","kid":"';

    jwk += base64urlEncode(keyId);

    jwk += '","k":"';

    jwk += base64urlEncode(key);

    jwk += '"}';

    return jwk;

};