diff --git a/spec/unit/utils.spec.ts b/spec/unit/utils.spec.ts
index 340acf92d..03f663ab3 100644
--- a/spec/unit/utils.spec.ts
+++ b/spec/unit/utils.spec.ts
@@ -109,18 +109,6 @@ describe("utils", function() {
         });
     });
 
-    describe("checkObjectHasNoAdditionalKeys", function() {
-        it("should throw for extra keys", function() {
-            expect(function() {
-                utils.checkObjectHasNoAdditionalKeys({ foo: "bar", baz: 4 }, ["foo"]);
-            }).toThrow();
-
-            expect(function() {
-                utils.checkObjectHasNoAdditionalKeys({ foo: "bar" }, ["foo"]);
-            }).not.toThrow();
-        });
-    });
-
     describe("deepCompare", function() {
         const assert = {
             isTrue: function(x: any) {
diff --git a/src/crypto/api.ts b/src/crypto/api.ts
index abe18469f..bedc5e603 100644
--- a/src/crypto/api.ts
+++ b/src/crypto/api.ts
@@ -109,11 +109,6 @@ export interface ISecretStorageKeyInfo {
     passphrase: IPassphraseInfo;
 }
 
-export interface ISecretStorageKey {
-    keyId: string;
-    keyInfo: ISecretStorageKeyInfo;
-}
-
 export interface IPassphraseInfo {
     algorithm: "m.pbkdf2";
     iterations: number;
diff --git a/src/crypto/verification/Error.ts b/src/crypto/verification/Error.ts
index 60faacf33..35ea7003d 100644
--- a/src/crypto/verification/Error.ts
+++ b/src/crypto/verification/Error.ts
@@ -46,13 +46,6 @@ export const newUserCancelledError = errorFactory("m.user", "Cancelled by user")
  */
 export const newTimeoutError = errorFactory("m.timeout", "Timed out");
 
-/**
- * The transaction is unknown.
- */
-export const newUnknownTransactionError = errorFactory(
-    "m.unknown_transaction", "Unknown transaction",
-);
-
 /**
  * An unknown method was selected.
  */
@@ -72,11 +65,6 @@ export const newKeyMismatchError = errorFactory(
     "m.key_mismatch", "Key mismatch",
 );
 
-/**
- * The user does not match.
- */
-export const newUserMismatchError = errorFactory("m.user_error", "User mismatch");
-
 /**
  * An invalid message was sent.
  */
diff --git a/src/utils.ts b/src/utils.ts
index 4885fb948..6cf459097 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -144,23 +144,6 @@ export function checkObjectHasKeys(obj: object, keys: string[]) {
     }
 }
 
-/**
- * Checks that the given object has no extra keys other than the specified ones.
- * @param {Object} obj The object to check.
- * @param {string[]} allowedKeys The list of allowed key names.
- * @throws If there are extra keys.
- */
-export function checkObjectHasNoAdditionalKeys(obj: object, allowedKeys: string[]): void {
-    for (const key in obj) {
-        if (!obj.hasOwnProperty(key)) {
-            continue;
-        }
-        if (allowedKeys.indexOf(key) === -1) {
-            throw new Error("Unknown key: " + key);
-        }
-    }
-}
-
 /**
  * Deep copy the given object. The object MUST NOT have circular references and
  * MUST NOT have functions.
@@ -283,69 +266,6 @@ export function deepSortedObjectEntries(obj: any): [string, any][] {
     return pairs;
 }
 
-/**
- * Inherit the prototype methods from one constructor into another. This is a
- * port of the Node.js implementation with an Object.create polyfill.
- *
- * @param {function} ctor Constructor function which needs to inherit the
- *     prototype.
- * @param {function} superCtor Constructor function to inherit prototype from.
- */
-export function inherits(ctor: Function, superCtor: Function) {
-    // Add util.inherits from Node.js
-    // Source:
-    // https://github.com/joyent/node/blob/master/lib/util.js
-    // Copyright Joyent, Inc. and other Node contributors.
-    //
-    // Permission is hereby granted, free of charge, to any person obtaining a
-    // copy of this software and associated documentation files (the
-    // "Software"), to deal in the Software without restriction, including
-    // without limitation the rights to use, copy, modify, merge, publish,
-    // distribute, sublicense, and/or sell copies of the Software, and to permit
-    // persons to whom the Software is furnished to do so, subject to the
-    // following conditions:
-    //
-    // The above copyright notice and this permission notice shall be included
-    // in all copies or substantial portions of the Software.
-    //
-    // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
-    // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-    // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
-    // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
-    // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
-    // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
-    // USE OR OTHER DEALINGS IN THE SOFTWARE.
-    (ctor as any).super_ = superCtor;
-    ctor.prototype = Object.create(superCtor.prototype, {
-        constructor: {
-            value: ctor,
-            enumerable: false,
-            writable: true,
-            configurable: true,
-        },
-    });
-}
-
-/**
- * Polyfills inheritance for prototypes by allowing different kinds of
- * super types. Typically prototypes would use `SuperType.call(this, params)`
- * though this doesn't always work in some environments - this function
- * falls back to using `Object.assign()` to clone a constructed copy
- * of the super type onto `thisArg`.
- * @param {any} thisArg The child instance. Modified in place.
- * @param {any} SuperType The type to act as a super instance
- * @param {any} params Arguments to supply to the super type's constructor
- */
-export function polyfillSuper(thisArg: any, SuperType: any, ...params: any[]) {
-    try {
-        SuperType.call(thisArg, ...params);
-    } catch (e) {
-        // fall back to Object.assign to just clone the thing
-        const fakeSuper = new SuperType(...params);
-        Object.assign(thisArg, fakeSuper);
-    }
-}
-
 /**
  * Returns whether the given value is a finite number without type-coercion
  *