Attempt to wrap the IE11 (msCrypto) implementation of the WebCryptoAPI (based on the spec before Promise) with a promise API inside an AngularJS based application using $q.

gistfile1.js

var qmsCrypto = {
    subtle : {
        importKey : function(format, keyData, algorithm, extractable, keyUsages) {
            var deferred = $q.defer();

            var op = window.msCrypto.subtle.importKey(format, keyData, algorithm, extractable, keyUsages);
            op.onerror = function (evt) {
                deferred.reject(evt.toString());
                $scope.$apply();
            };

            op.oncomplete = function (evt) {
                deferred.resolve(evt.target.result);
                $scope.$apply();
            };

            return deferred.promise;
        },
        encrypt : function(algorithm, key, buffer) {
            var deferred = $q.defer();

            var op = window.msCrypto.subtle.encrypt(algorithm, key, buffer);
            op.onerror = function (evt) {
                deferred.reject(evt.toString());
                $scope.$apply();
            };

            op.oncomplete = function (evt) {
                deferred.resolve(evt.target.result);
                $scope.$apply();
            };

            return deferred.promise;
        },
        decrypt : function(algorithm, key, buffer) {
            var deferred = $q.defer();

            var op = window.msCrypto.subtle.decrypt(algorithm, key, buffer);
            op.onerror = function (evt) {
                deferred.reject(evt.toString());
                $scope.$apply();
            };

            op.oncomplete = function (evt) {
                deferred.resolve(evt.target.result);
                $scope.$apply();
            };

            return deferred.promise;
        }

    }
};