authorizer.js

exports.handler =  function(event, context, callback) {
    var token = event.authorizationToken;

    if (token == 'Basic XXXXXXXXXXXXXX') {
      return callback(null, generatePolicy('user', 'Allow', event.methodArn));
    }
    else {
      return callback(null, generatePolicy('user', 'Deny', event.methodArn));
    }
};

var generatePolicy = function(principalId, effect, resource) {
    var authResponse = {};

    authResponse.principalId = principalId;
    
    if (effect && resource) {
        var policyDocument = {};
        policyDocument.Version = '2012-10-17';
        policyDocument.Statement = [];
        var statementOne = {};
        statementOne.Action = 'execute-api:Invoke';
        statementOne.Effect = effect;
        statementOne.Resource = resource;
        policyDocument.Statement[0] = statementOne;
        authResponse.policyDocument = policyDocument;
    }

    return authResponse;
}