diff --git a/src/message.js b/src/message.js
index 159c003e..7fd3431d 100644
--- a/src/message.js
+++ b/src/message.js
@@ -17,7 +17,7 @@
 
 import * as stream from '@openpgp/web-stream-tools';
 import { armor, unarmor } from './encoding/armor';
-import { Argon2OutOfMemoryError } from './type/s2k';
+import { Argon2OutOfMemoryError } from './type/s2k/index.ts';
 import defaultConfig from './config';
 import crypto from './crypto';
 import enums from './enums';
diff --git a/src/packet/secret_key.js b/src/packet/secret_key.js
index acebd0a6..d260d12d 100644
--- a/src/packet/secret_key.js
+++ b/src/packet/secret_key.js
@@ -16,7 +16,7 @@
 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 
 import PublicKeyPacket from './public_key';
-import { newS2KFromConfig, newS2KFromType } from '../type/s2k';
+import { newS2KFromConfig, newS2KFromType } from '../type/s2k/index.ts';
 import crypto from '../crypto';
 import enums from '../enums';
 import util from '../util';
diff --git a/src/packet/sym_encrypted_session_key.js b/src/packet/sym_encrypted_session_key.js
index 2dcfea54..6e8cfc56 100644
--- a/src/packet/sym_encrypted_session_key.js
+++ b/src/packet/sym_encrypted_session_key.js
@@ -15,7 +15,7 @@
 // License along with this library; if not, write to the Free Software
 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 
-import { newS2KFromConfig, newS2KFromType } from '../type/s2k';
+import { newS2KFromConfig, newS2KFromType } from '../type/s2k/index.ts';
 import defaultConfig from '../config';
 import crypto from '../crypto';
 import computeHKDF from '../crypto/hkdf';
diff --git a/src/type/s2k/argon2.js b/src/type/s2k/argon2.ts
similarity index 90%
rename from src/type/s2k/argon2.js
rename to src/type/s2k/argon2.ts
index f79e3ef6..5636d608 100644
--- a/src/type/s2k/argon2.js
+++ b/src/type/s2k/argon2.ts
@@ -8,7 +8,7 @@ const ARGON2_VERSION = 0x13;
 const ARGON2_SALT_SIZE = 16;
 
 export class Argon2OutOfMemoryError extends Error {
-  constructor(...params) {
+  constructor(...params: string[]) {
     super(...params);
 
     if (Error.captureStackTrace) {
@@ -20,16 +20,22 @@ export class Argon2OutOfMemoryError extends Error {
 }
 
 // cache argon wasm module
-let loadArgonWasmModule;
-let argon2Promise;
+let loadArgonWasmModule: Function;
+let argon2Promise: Promise<Function>;
 // reload wasm module above this treshold, to deallocated used memory
 const ARGON2_WASM_MEMORY_THRESHOLD_RELOAD = 2 << 19;
 
 class Argon2S2K {
+    type: string;
+    salt: Uint8Array | null;
+    t: number;
+    p: number;
+    encodedM: number;
   /**
   * @param {Object} [config] - Full configuration, defaults to openpgp.config
   */
   constructor(config = defaultConfig) {
+    
     const { passes, parallelism, memoryExponent } = config.s2kArgon2Params;
 
     this.type = 'argon2';
@@ -52,7 +58,7 @@ class Argon2S2K {
   * @param {Uint8Array} bytes - Payload of argon2 string-to-key specifier
   * @returns {Integer} Actual length of the object.
   */
-  read(bytes) {
+  read(bytes: Uint8Array) {
     let i = 0;
 
     this.salt = bytes.subarray(i, i + 16);
@@ -69,7 +75,7 @@ class Argon2S2K {
   * Serializes s2k information
   * @returns {Uint8Array} Binary representation of s2k.
   */
-  write() {
+  write(): Uint8Array {
     const arr = [
       new Uint8Array([enums.write(enums.s2k, this.type)]),
       this.salt,
@@ -87,7 +93,7 @@ class Argon2S2K {
   * @throws {Argon2OutOfMemoryError|Errors}
   * @async
   */
-  async produceKey(passphrase, keySize) {
+  async produceKey(passphrase: string, keySize: number): Promise<Uint8Array> {
     const decodedM = 2 << (this.encodedM - 1);
 
     try {
@@ -120,7 +126,7 @@ class Argon2S2K {
       }
       return hash;
     } catch (e) {
-      if (e.message && (
+      if (e instanceof Error && e.message && (
         e.message.includes('Unable to grow instance memory') || // Chrome
         e.message.includes('failed to grow memory') || // Firefox
         e.message.includes('WebAssembly.Memory.grow') || // Safari
diff --git a/src/type/s2k/generic.js b/src/type/s2k/generic.ts
similarity index 91%
rename from src/type/s2k/generic.js
rename to src/type/s2k/generic.ts
index 76b81f5b..7c3dc4f7 100644
--- a/src/type/s2k/generic.js
+++ b/src/type/s2k/generic.ts
@@ -34,10 +34,14 @@ import { UnsupportedError } from '../../packet/packet';
 import util from '../../util';
 
 class GenericS2K {
+  algorithm: number;
+  type: string;
+  c: number;
+  salt: Uint8Array | null;
   /**
    * @param {Object} [config] - Full configuration, defaults to openpgp.config
    */
-  constructor(s2kType, config = defaultConfig) {
+  constructor(s2kType: number, config = defaultConfig) {
     /**
      * Hash function identifier, or 0 for gnu-dummy keys
      * @type {module:enums.hash | 0}
@@ -76,7 +80,7 @@ class GenericS2K {
    * @param {Uint8Array} bytes - Payload of string-to-key specifier
    * @returns {Integer} Actual length of the object.
    */
-  read(bytes) {
+  read(bytes: Uint8Array): Number {
     let i = 0;
     this.algorithm = bytes[i++];
 
@@ -123,7 +127,7 @@ class GenericS2K {
    * Serializes s2k information
    * @returns {Uint8Array} Binary representation of s2k.
    */
-  write() {
+  write(): Uint8Array {
     if (this.type === 'gnu-dummy') {
       return new Uint8Array([101, 0, ...util.stringToUint8Array('GNU'), 1]);
     }
@@ -133,10 +137,10 @@ class GenericS2K {
       case 'simple':
         break;
       case 'salted':
-        arr.push(this.salt);
+        this.salt && arr.push(this.salt);
         break;
       case 'iterated':
-        arr.push(this.salt);
+        this.salt &&arr.push(this.salt);
         arr.push(new Uint8Array([this.c]));
         break;
       case 'gnu':
@@ -156,8 +160,8 @@ class GenericS2K {
    * hashAlgorithm hash length
    * @async
    */
-  async produceKey(passphrase, numBytes) {
-    passphrase = util.encodeUTF8(passphrase);
+  async produceKey(passphrase: string, numBytes: number): Promise<Uint8Array> {
+    const encodedPassphrase = util.encodeUTF8(passphrase);
 
     const arr = [];
     let rlength = 0;
@@ -167,13 +171,13 @@ class GenericS2K {
       let toHash;
       switch (this.type) {
         case 'simple':
-          toHash = util.concatUint8Array([new Uint8Array(prefixlen), passphrase]);
+          toHash = util.concatUint8Array([new Uint8Array(prefixlen), encodedPassphrase]);
           break;
         case 'salted':
-          toHash = util.concatUint8Array([new Uint8Array(prefixlen), this.salt, passphrase]);
+          toHash = util.concatUint8Array([new Uint8Array(prefixlen), this.salt, encodedPassphrase]);
           break;
         case 'iterated': {
-          const data = util.concatUint8Array([this.salt, passphrase]);
+          const data = util.concatUint8Array([this.salt, encodedPassphrase]);
           let datalen = data.length;
           const count = Math.max(this.getCount(), datalen);
           toHash = new Uint8Array(prefixlen + count);
diff --git a/src/type/s2k/index.js b/src/type/s2k/index.ts
similarity index 89%
rename from src/type/s2k/index.js
rename to src/type/s2k/index.ts
index 8a725c18..a54c5e1f 100644
--- a/src/type/s2k/index.js
+++ b/src/type/s2k/index.ts
@@ -13,7 +13,7 @@ const allowedS2KTypesForEncryption = new Set([enums.s2k.argon2, enums.s2k.iterat
  * @returns {Object} New s2k object
  * @throws {Error} for unknown or unsupported types
  */
-export function newS2KFromType(type, config = defaultConfig) {
+export function newS2KFromType (type: number, config = defaultConfig): Argon2S2K | GenericS2K {
   switch (type) {
     case enums.s2k.argon2:
       return new Argon2S2K(config);
@@ -33,7 +33,7 @@ export function newS2KFromType(type, config = defaultConfig) {
  * @returns {Object} New s2k object
  * @throws {Error} for unknown or unsupported types
  */
-export function newS2KFromConfig(config) {
+export function newS2KFromConfig(config = defaultConfig) {
   const { s2kType } = config;
 
   if (!allowedS2KTypesForEncryption.has(s2kType)) {