diff --git a/src/crypto/aes_kw.js b/src/crypto/aes_kw.js
index 669858b0..14d5839c 100644
--- a/src/crypto/aes_kw.js
+++ b/src/crypto/aes_kw.js
@@ -29,8 +29,8 @@ import util from '../util';
 /**
  * AES key wrap
  * @function
- * @param {String} key
- * @param {String} data
+ * @param {Uint8Array} key
+ * @param {Uint8Array} data
  * @returns {Uint8Array}
  */
 export function wrap(key, data) {
diff --git a/src/crypto/crypto.js b/src/crypto/crypto.js
index 5672e8e9..e1558b3d 100644
--- a/src/crypto/crypto.js
+++ b/src/crypto/crypto.js
@@ -247,7 +247,7 @@ export function parseEncSessionKeyParams(algo, bytes) {
  * @param {Object}                  params  The key parameters indexed by name
  * @returns {Uint8Array}                    The array containing the MPIs
  */
-export function serializeKeyParams(algo, params) {
+export function serializeParams(algo, params) {
   const orderedParams = Object.keys(params).map(name => {
     const param = params[name];
     return util.isUint8Array(param) ? util.uint8ArrayToMpi(param) : param.write();
diff --git a/src/crypto/public_key/elliptic/ecdh.js b/src/crypto/public_key/elliptic/ecdh.js
index 53a4852d..9e1a90af 100644
--- a/src/crypto/public_key/elliptic/ecdh.js
+++ b/src/crypto/public_key/elliptic/ecdh.js
@@ -38,7 +38,6 @@ import hash from '../../hash';
 import enums from '../../../enums';
 import util from '../../../util';
 import * as pkcs5 from '../../pkcs5';
-import MPI from '../../../type/mpi';
 import { keyFromPublic, keyFromPrivate, getIndutnyCurve } from './indutnyKey';
 
 const webCrypto = util.getWebCrypto();
@@ -135,14 +134,14 @@ async function genPublicEphemeralKey(curve, Q) {
  * @async
  */
 export async function encrypt(oid, kdfParams, data, Q, fingerprint) {
-  const m = new MPI(pkcs5.encode(data));
+  const m = pkcs5.encode(data);
 
   const curve = new Curve(oid);
   const { publicKey, sharedKey } = await genPublicEphemeralKey(curve, Q);
   const param = buildEcdhParam(enums.publicKey.ecdh, oid, kdfParams, fingerprint);
   const cipher_algo = enums.read(enums.symmetric, kdfParams.cipher);
   const Z = await kdf(kdfParams.hash, sharedKey, cipher[cipher_algo].keySize, param);
-  const wrappedKey = aes_kw.wrap(Z, m.toString());
+  const wrappedKey = aes_kw.wrap(Z, m);
   return { publicKey, wrappedKey };
 }
 
diff --git a/src/crypto/public_key/elliptic/eddsa.js b/src/crypto/public_key/elliptic/eddsa.js
index 9c2e99a4..f3845228 100644
--- a/src/crypto/public_key/elliptic/eddsa.js
+++ b/src/crypto/public_key/elliptic/eddsa.js
@@ -38,8 +38,8 @@ nacl.hash = bytes => new Uint8Array(sha512().update(bytes).digest());
  * @param  {Uint8Array}        publicKey    Public key
  * @param  {Uint8Array}        privateKey   Private key used to sign the message
  * @param  {Uint8Array}        hashed       The hashed message
- * @returns {{R: Uint8Array,
- *            S: Uint8Array}}               Signature of the message
+ * @returns {{r: Uint8Array,
+ *            s: Uint8Array}}               Signature of the message
  * @async
  */
 export async function sign(oid, hash_algo, message, publicKey, privateKey, hashed) {
@@ -47,8 +47,8 @@ export async function sign(oid, hash_algo, message, publicKey, privateKey, hashe
   const signature = nacl.sign.detached(hashed, secretKey);
   // EdDSA signature params are returned in little-endian format
   return {
-    R: signature.subarray(0, 32),
-    S: signature.subarray(32)
+    r: signature.subarray(0, 32),
+    s: signature.subarray(32)
   };
 }
 
@@ -56,16 +56,16 @@ export async function sign(oid, hash_algo, message, publicKey, privateKey, hashe
  * Verifies if a signature is valid for a message
  * @param  {module:type/oid}   oid       Elliptic curve object identifier
  * @param  {module:enums.hash} hash_algo Hash algorithm used in the signature
- * @param  {{R: Uint8Array,
-             S: Uint8Array}}   signature Signature to verify the message
+ * @param  {{r: Uint8Array,
+             s: Uint8Array}}   signature Signature to verify the message
  * @param  {Uint8Array}        m         Message to verify
  * @param  {Uint8Array}        publicKey Public key used to verify the message
  * @param  {Uint8Array}        hashed    The hashed message
  * @returns {Boolean}
  * @async
  */
-export async function verify(oid, hash_algo, { R, S }, m, publicKey, hashed) {
-  const signature = util.concatUint8Array([R, S]);
+export async function verify(oid, hash_algo, { r, s }, m, publicKey, hashed) {
+  const signature = util.concatUint8Array([r, s]);
   return nacl.sign.detached.verify(hashed, signature, publicKey.subarray(1));
 }
 /**
diff --git a/src/crypto/signature.js b/src/crypto/signature.js
index 2adda547..fc42f2ba 100644
--- a/src/crypto/signature.js
+++ b/src/crypto/signature.js
@@ -10,48 +10,87 @@ import publicKey from './public_key';
 import enums from '../enums';
 import util from '../util';
 
+
+/**
+ * Parse signature in binary form to get the parameters.
+ * See {@link https://tools.ietf.org/html/rfc4880#section-9.1|RFC 4880 9.1}
+ * See {@link https://tools.ietf.org/html/rfc4880#section-5.2.2|RFC 4880 5.2.2.}
+ * @param {module:enums.publicKey} algo       Public key algorithm
+ * @param {Uint8Array}             signature  Data for which the signature was created
+ * @returns {Object}                          True if signature is valid
+ * @async
+ */
+export function parseSignatureParams(algo, signature) {
+  let read = 0;
+  switch (algo) {
+    // Algorithm-Specific Fields for RSA signatures:
+    // -  MPI of RSA signature value m**d mod n.
+    case enums.publicKey.rsaEncryptSign:
+    case enums.publicKey.rsaEncrypt:
+    case enums.publicKey.rsaSign: {
+      const s = util.readMPI(signature.subarray(read));
+      return { s };
+    }
+    // Algorithm-Specific Fields for DSA or ECDSA signatures:
+    // -  MPI of DSA or ECDSA value r.
+    // -  MPI of DSA or ECDSA value s.
+    case enums.publicKey.dsa:
+    case enums.publicKey.ecdsa:
+    {
+      const r = util.readMPI(signature.subarray(read)); read += r.length + 2;
+      const s = util.readMPI(signature.subarray(read));
+      return { r, s };
+    }
+    // Algorithm-Specific Fields for EdDSA signatures:
+    // -  MPI of an EC point r.
+    // -  EdDSA value s, in MPI, in the little endian representation.
+    // EdDSA signature parameters are encoded in little-endian format
+    // https://tools.ietf.org/html/rfc8032#section-5.1.2
+    case enums.publicKey.eddsa: {
+      const r = util.padToLength(util.readMPI(signature.subarray(read)), 32, 'le'); read += r.length + 2;
+      const s = util.padToLength(util.readMPI(signature.subarray(read)), 32, 'le');
+      return { r, s };
+    }
+    default:
+      throw new Error('Invalid signature algorithm.');
+  }
+}
+
 /**
  * Verifies the signature provided for data using specified algorithms and public key parameters.
  * See {@link https://tools.ietf.org/html/rfc4880#section-9.1|RFC 4880 9.1}
  * and {@link https://tools.ietf.org/html/rfc4880#section-9.4|RFC 4880 9.4}
  * for public key and hash algorithms.
- * @param {module:enums.publicKey} algo             Public key algorithm
- * @param {module:enums.hash}      hash_algo        Hash algorithm
- * @param {Array<module:type/mpi>} msg_MPIs         Algorithm-specific signature parameters
- * @param {Object}                 publicParams  Algorithm-specific public key parameters
- * @param {Uint8Array}             data             Data for which the signature was created
- * @param {Uint8Array}             hashed           The hashed data
- * @returns {Boolean}                               True if signature is valid
+ * @param {module:enums.publicKey}  algo          Public key algorithm
+ * @param {module:enums.hash}       hashAlgo      Hash algorithm
+ * @param {Object}                  signature     Named algorithm-specific signature parameters
+ * @param {Object}                  publicParams  Algorithm-specific public key parameters
+ * @param {Uint8Array}              data          Data for which the signature was created
+ * @param {Uint8Array}              hashed        The hashed data
+ * @returns {Boolean}                             True if signature is valid
  * @async
  */
-export async function verify(algo, hash_algo, msg_MPIs, publicParams, data, hashed) {
+export async function verify(algo, hashAlgo, signature, publicParams, data, hashed) {
   switch (algo) {
     case enums.publicKey.rsaEncryptSign:
     case enums.publicKey.rsaEncrypt:
     case enums.publicKey.rsaSign: {
       const { n, e } = publicParams;
-      const m = msg_MPIs[0].toUint8Array('be', n.length);
-      return publicKey.rsa.verify(hash_algo, data, m, n, e, hashed);
+      const { s } = signature;
+      return publicKey.rsa.verify(hashAlgo, data, s, n, e, hashed);
     }
     case enums.publicKey.dsa: {
-      const r = await msg_MPIs[0].toUint8Array();
-      const s = await msg_MPIs[1].toUint8Array();
       const { g, p, q, y } = publicParams;
-      return publicKey.dsa.verify(hash_algo, r, s, hashed, g, p, q, y);
+      const { r, s } = signature;
+      return publicKey.dsa.verify(hashAlgo, r, s, hashed, g, p, q, y);
     }
     case enums.publicKey.ecdsa: {
       const { oid, Q } = publicParams;
-      const signature = { r: msg_MPIs[0].toUint8Array(), s: msg_MPIs[1].toUint8Array() };
-      return publicKey.elliptic.ecdsa.verify(oid, hash_algo, signature, data, Q, hashed);
+      return publicKey.elliptic.ecdsa.verify(oid, hashAlgo, signature, data, Q, hashed);
     }
     case enums.publicKey.eddsa: {
       const { oid, Q } = publicParams;
-      // EdDSA signature params are expected in little-endian format
-      const signature = {
-        R: msg_MPIs[0].toUint8Array('le', 32),
-        S: msg_MPIs[1].toUint8Array('le', 32)
-      };
-      return publicKey.elliptic.eddsa.verify(oid, hash_algo, signature, data, Q, hashed);
+      return publicKey.elliptic.eddsa.verify(oid, hashAlgo, signature, data, Q, hashed);
     }
     default:
       throw new Error('Invalid signature algorithm.');
@@ -64,15 +103,15 @@ export async function verify(algo, hash_algo, msg_MPIs, publicParams, data, hash
  * and {@link https://tools.ietf.org/html/rfc4880#section-9.4|RFC 4880 9.4}
  * for public key and hash algorithms.
  * @param {module:enums.publicKey} algo             Public key algorithm
- * @param {module:enums.hash}      hash_algo        Hash algorithm
+ * @param {module:enums.hash}      hashAlgo         Hash algorithm
  * @param {Object}                 publicKeyParams  Algorithm-specific public and private key parameters
  * @param {Object}                 privateKeyParams Algorithm-specific public and private key parameters
  * @param {Uint8Array}             data             Data to be signed
  * @param {Uint8Array}             hashed           The hashed data
- * @returns {Uint8Array} Signature
+ * @returns {Object} Signature                      Object containing named signature parameters
  * @async
  */
-export async function sign(algo, hash_algo, publicKeyParams, privateKeyParams, data, hashed) {
+export async function sign(algo, hashAlgo, publicKeyParams, privateKeyParams, data, hashed) {
   if (!publicKeyParams || !privateKeyParams) {
     throw new Error('Missing key parameters');
   }
@@ -82,17 +121,13 @@ export async function sign(algo, hash_algo, publicKeyParams, privateKeyParams, d
     case enums.publicKey.rsaSign: {
       const { n, e } = publicKeyParams;
       const { d, p, q, u } = privateKeyParams;
-      const signature = await publicKey.rsa.sign(hash_algo, data, n, e, d, p, q, u, hashed);
-      return util.uint8ArrayToMpi(signature);
+      const s = await publicKey.rsa.sign(hashAlgo, data, n, e, d, p, q, u, hashed);
+      return { s };
     }
     case enums.publicKey.dsa: {
       const { g, p, q } = publicKeyParams;
       const { x } = privateKeyParams;
-      const signature = await publicKey.dsa.sign(hash_algo, hashed, g, p, q, x);
-      return util.concatUint8Array([
-        util.uint8ArrayToMpi(signature.r),
-        util.uint8ArrayToMpi(signature.s)
-      ]);
+      return publicKey.dsa.sign(hashAlgo, hashed, g, p, q, x);
     }
     case enums.publicKey.elgamal: {
       throw new Error('Signing with Elgamal is not defined in the OpenPGP standard.');
@@ -100,20 +135,12 @@ export async function sign(algo, hash_algo, publicKeyParams, privateKeyParams, d
     case enums.publicKey.ecdsa: {
       const { oid, Q } = publicKeyParams;
       const { d } = privateKeyParams;
-      const signature = await publicKey.elliptic.ecdsa.sign(oid, hash_algo, data, Q, d, hashed);
-      return util.concatUint8Array([
-        util.uint8ArrayToMpi(signature.r),
-        util.uint8ArrayToMpi(signature.s)
-      ]);
+      return publicKey.elliptic.ecdsa.sign(oid, hashAlgo, data, Q, d, hashed);
     }
     case enums.publicKey.eddsa: {
       const { oid, Q } = publicKeyParams;
       const { seed } = privateKeyParams;
-      const signature = await publicKey.elliptic.eddsa.sign(oid, hash_algo, data, Q, seed, hashed);
-      return util.concatUint8Array([
-        util.uint8ArrayToMpi(signature.R),
-        util.uint8ArrayToMpi(signature.S)
-      ]);
+      return publicKey.elliptic.eddsa.sign(oid, hashAlgo, data, Q, seed, hashed);
     }
     default:
       throw new Error('Invalid signature algorithm.');
diff --git a/src/index.js b/src/index.js
index b1efb6a8..6d512fd3 100644
--- a/src/index.js
+++ b/src/index.js
@@ -52,12 +52,6 @@ export { default as util } from './util';
  */
 export * from './packet';
 
-/**
- * @see module:type/mpi
- * @name module:openpgp.MPI
- */
-export { default as MPI } from './type/mpi';
-
 /**
  * @see module:type/s2k
  * @name module:openpgp.S2K
diff --git a/src/key/helper.js b/src/key/helper.js
index 6fa49059..9a7eb485 100644
--- a/src/key/helper.js
+++ b/src/key/helper.js
@@ -238,7 +238,7 @@ export async function mergeSignatures(source, dest, attr, checkFn) {
       await Promise.all(source.map(async function(sourceSig) {
         if (!sourceSig.isExpired() && (!checkFn || await checkFn(sourceSig)) &&
             !dest[attr].some(function(destSig) {
-              return util.equalsUint8Array(destSig.signature, sourceSig.signature);
+              return util.equalsUint8Array(destSig.write_params(), sourceSig.write_params());
             })) {
           dest[attr].push(sourceSig);
         }
diff --git a/src/packet/public_key.js b/src/packet/public_key.js
index 8d6542ca..b2ac9728 100644
--- a/src/packet/public_key.js
+++ b/src/packet/public_key.js
@@ -19,7 +19,6 @@
 
 /**
  * @requires type/keyid
- * @requires type/mpi
  * @requires config
  * @requires crypto
  * @requires enums
@@ -142,7 +141,7 @@ class PublicKeyPacket {
     const algo = enums.write(enums.publicKey, this.algorithm);
     arr.push(new Uint8Array([algo]));
 
-    const params = crypto.serializeKeyParams(algo, this.publicParams);
+    const params = crypto.serializeParams(algo, this.publicParams);
     if (this.version === 5) {
       // A four-octet scalar octet count for the following key material
       arr.push(util.writeNumber(params.length, 4));
diff --git a/src/packet/public_key_encrypted_session_key.js b/src/packet/public_key_encrypted_session_key.js
index db0ca210..f414007a 100644
--- a/src/packet/public_key_encrypted_session_key.js
+++ b/src/packet/public_key_encrypted_session_key.js
@@ -17,7 +17,6 @@
 
 /**
  * @requires type/keyid
- * @requires type/mpi
  * @requires crypto
  * @requires enums
  * @requires util
@@ -56,8 +55,8 @@ class PublicKeyEncryptedSessionKeyPacket {
     this.sessionKey = null;
     this.sessionKeyAlgorithm = null;
 
-    /** @type {Array<module:type/mpi>} */
-    this.encrypted = [];
+    /** @type {Object} */
+    this.encrypted = {};
   }
 
   /**
@@ -86,7 +85,7 @@ class PublicKeyEncryptedSessionKeyPacket {
       new Uint8Array([this.version]),
       this.publicKeyId.write(),
       new Uint8Array([enums.write(enums.publicKey, this.publicKeyAlgorithm)]),
-      crypto.serializeKeyParams(algo, this.encrypted)
+      crypto.serializeParams(algo, this.encrypted)
     ];
 
     return util.concatUint8Array(arr);
diff --git a/src/packet/secret_key.js b/src/packet/secret_key.js
index 8ccd3dbe..f8f92f84 100644
--- a/src/packet/secret_key.js
+++ b/src/packet/secret_key.js
@@ -211,7 +211,7 @@ class SecretKeyPacket extends PublicKeyPacket {
     if (!this.isDummy()) {
       if (!this.s2k_usage) {
         const algo = enums.write(enums.publicKey, this.algorithm);
-        const cleartextParams = crypto.serializeKeyParams(algo, this.privateParams);
+        const cleartextParams = crypto.serializeParams(algo, this.privateParams);
         this.keyMaterial = util.concatUint8Array([
           cleartextParams,
           util.writeChecksum(cleartextParams)
@@ -294,7 +294,7 @@ class SecretKeyPacket extends PublicKeyPacket {
     this.s2k = new type_s2k();
     this.s2k.salt = await crypto.random.getRandomBytes(8);
     const algo = enums.write(enums.publicKey, this.algorithm);
-    const cleartext = crypto.serializeKeyParams(algo, this.privateParams);
+    const cleartext = crypto.serializeParams(algo, this.privateParams);
     this.symmetric = 'aes256';
     const key = await produceEncryptionKey(this.s2k, passphrase, this.symmetric);
     const blockLen = crypto.cipher[this.symmetric].blockSize;
diff --git a/src/packet/signature.js b/src/packet/signature.js
index 275e7c7e..ffd7da0c 100644
--- a/src/packet/signature.js
+++ b/src/packet/signature.js
@@ -19,7 +19,6 @@
  * @requires web-stream-tools
  * @requires packet/packet
  * @requires type/keyid
- * @requires type/mpi
  * @requires crypto
  * @requires enums
  * @requires util
@@ -28,7 +27,6 @@
 import stream from 'web-stream-tools';
 import { readSimpleLength, writeSimpleLength } from './packet';
 import type_keyid from '../type/keyid.js';
-import type_mpi from '../type/mpi.js';
 import crypto from '../crypto';
 import enums from '../enums';
 import util from '../util';
@@ -133,7 +131,19 @@ class SignaturePacket {
     this.signedHashValue = bytes.subarray(i, i + 2);
     i += 2;
 
-    this.signature = bytes.subarray(i, bytes.length);
+    this.params = crypto.signature.parseSignatureParams(this.publicKeyAlgorithm, bytes.subarray(i, bytes.length));
+  }
+
+  /**
+   * @returns {Uint8Array | ReadableStream<Uint8Array>}
+   */
+  write_params() {
+    if (this.params instanceof Promise) {
+      return stream.fromAsync(
+        async () => crypto.serializeParams(this.publicKeyAlgorithm, await this.params)
+      );
+    }
+    return crypto.serializeParams(this.publicKeyAlgorithm, this.params);
   }
 
   write() {
@@ -141,7 +151,7 @@ class SignaturePacket {
     arr.push(this.signatureData);
     arr.push(this.write_unhashed_sub_packets());
     arr.push(this.signedHashValue);
-    arr.push(stream.clone(this.signature));
+    arr.push(this.write_params());
     return util.concat(arr);
   }
 
@@ -181,9 +191,9 @@ class SignaturePacket {
       publicKeyAlgorithm, hashAlgorithm, key.publicParams, key.privateParams, toHash, await stream.readToEnd(hash)
     );
     if (streaming) {
-      this.signature = stream.fromAsync(signed);
+      this.params = signed();
     } else {
-      this.signature = await signed();
+      this.params = await signed();
 
       // Store the fact that this signature is valid, e.g. for when we call `await
       // getLatestValidSignature(this.revocationSignatures, key, data)` later.
@@ -661,6 +671,7 @@ class SignaturePacket {
    * @param {module:enums.signature} signatureType expected signature type
    * @param {String|Object} data data which on the signature applies
    * @param {Boolean} detached (optional) whether to verify a detached signature
+   * @param {Boolean} streaming (optional) whether to process data as a stream
    * @returns {Promise<Boolean>} True if message is verified, else false.
    * @async
    */
@@ -687,33 +698,10 @@ class SignaturePacket {
       throw new Error('Message digest did not match');
     }
 
-    let mpicount = 0;
-    // Algorithm-Specific Fields for RSA signatures:
-    //      - multiprecision number (MPI) of RSA signature value m**d mod n.
-    if (publicKeyAlgorithm > 0 && publicKeyAlgorithm < 4) {
-      mpicount = 1;
+    this.params = await this.params;
 
-    //    Algorithm-Specific Fields for DSA, ECDSA, and EdDSA signatures:
-    //      - MPI of DSA value r.
-    //      - MPI of DSA value s.
-    } else if (publicKeyAlgorithm === enums.publicKey.dsa ||
-              publicKeyAlgorithm === enums.publicKey.ecdsa ||
-              publicKeyAlgorithm === enums.publicKey.eddsa) {
-      mpicount = 2;
-    }
-
-    // EdDSA signature parameters are encoded in little-endian format
-    // https://tools.ietf.org/html/rfc8032#section-5.1.2
-    const endian = publicKeyAlgorithm === enums.publicKey.eddsa ? 'le' : 'be';
-    const mpi = [];
-    let i = 0;
-    this.signature = await stream.readToEnd(this.signature);
-    for (let j = 0; j < mpicount; j++) {
-      mpi[j] = new type_mpi();
-      i += mpi[j].read(this.signature.subarray(i, this.signature.length), endian);
-    }
     const verified = await crypto.signature.verify(
-      publicKeyAlgorithm, hashAlgorithm, mpi, key.publicParams,
+      publicKeyAlgorithm, hashAlgorithm, this.params, key.publicParams,
       toHash, hash
     );
     if (!verified) {
diff --git a/src/type/mpi.js b/src/type/mpi.js
deleted file mode 100644
index 6b5df1ef..00000000
--- a/src/type/mpi.js
+++ /dev/null
@@ -1,137 +0,0 @@
-// GPG4Browsers - An OpenPGP implementation in javascript
-// Copyright (C) 2011 Recurity Labs GmbH
-//
-// This library is free software; you can redistribute it and/or
-// modify it under the terms of the GNU Lesser General Public
-// License as published by the Free Software Foundation; either
-// version 3.0 of the License, or (at your option) any later version.
-//
-// This library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-// Lesser General Public License for more details.
-//
-// You should have received a copy of the GNU Lesser General Public
-// License along with this library; if not, write to the Free Software
-// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
-
-// Hint: We hold our MPIs as an array of octets in big endian format preceding a two
-// octet scalar: MPI: [a,b,c,d,e,f]
-// - MPI size: (a << 8) | b
-// - MPI = c | d << 8 | e << ((MPI.length -2)*8) | f ((MPI.length -2)*8)
-
-/**
- * Implementation of type MPI ({@link https://tools.ietf.org/html/rfc4880#section-3.2|RFC4880 3.2})
- * Multiprecision integers (also called MPIs) are unsigned integers used
- * to hold large integers such as the ones used in cryptographic
- * calculations.
- * An MPI consists of two pieces: a two-octet scalar that is the length
- * of the MPI in bits followed by a string of octets that contain the
- * actual integer.
- * @requires util
- * @module type/mpi
- */
-import util from '../util';
-
-class MPI {
-  constructor(data) {
-    /** An implementation dependent integer */
-    if (data instanceof MPI) {
-      this.data = data.data;
-    } else if (util.isBigInteger(data)) {
-      this.fromBigInteger(data);
-    } else if (util.isBN(data)) {
-      this.fromBN(data);
-    } else if (util.isUint8Array(data)) {
-      this.fromUint8Array(data);
-    } else if (util.isString(data)) {
-      this.fromString(data);
-    } else {
-      this.data = null;
-    }
-  }
-
-  /**
-   * Parsing function for a MPI ({@link https://tools.ietf.org/html/rfc4880#section-3.2|RFC 4880 3.2}).
-   * @param {Uint8Array|string} bytes  Payload of MPI data
-   * @param {'be'|'le'}     endian Endianness of the data; 'be' for big-endian or 'le' for little-endian
-   * @returns {Integer}          Length of data read
-   */
-  read(bytes, endian = 'be') {
-    if (util.isString(bytes)) {
-      bytes = util.strToUint8Array(bytes);
-    }
-
-    const bits = (bytes[0] << 8) | bytes[1];
-    const bytelen = (bits + 7) >>> 3;
-    const payload = bytes.subarray(2, 2 + bytelen);
-
-    this.fromUint8Array(payload, endian);
-
-    return 2 + bytelen;
-  }
-
-  /**
-   * Converts the mpi object to a bytes as specified in
-   * {@link https://tools.ietf.org/html/rfc4880#section-3.2|RFC4880 3.2}
-   * @param {String} endian Endianness of the payload; 'be' for big-endian or 'le' for little-endian
-   * @param {Integer} length Length of the data part of the MPI
-   * @returns {Uint8Aray} mpi Byte representation
-   */
-  write(endian, length) {
-    return util.uint8ArrayToMpi(this.toUint8Array(endian, length));
-  }
-
-  bitLength() {
-    return (this.data.length - 1) * 8 + util.nbits(this.data[0]);
-  }
-
-  byteLength() {
-    return this.data.length;
-  }
-
-  toUint8Array(endian, length) {
-    endian = endian || 'be';
-    length = length || this.data.length;
-
-    const payload = new Uint8Array(length);
-    const start = endian === 'le' ? 0 : length - this.data.length;
-    payload.set(this.data, start);
-    if (endian === 'le') {
-      payload.reverse();
-    }
-    return payload;
-  }
-
-  fromUint8Array(bytes, endian = 'be') {
-    this.data = new Uint8Array(bytes.length);
-    this.data.set(bytes);
-
-    if (endian === 'le') {
-      this.data.reverse();
-    }
-  }
-
-  toString() {
-    return util.uint8ArrayToStr(this.toUint8Array());
-  }
-
-  fromString(str, endian = 'be') {
-    this.fromUint8Array(util.strToUint8Array(str), endian);
-  }
-
-  async toBigInteger() {
-    const BigInteger = await util.getBigInteger();
-    return new BigInteger(this.toUint8Array());
-  }
-
-  fromBigInteger(n) {
-    this.data = n.toUint8Array();
-  }
-
-  fromBN(bn) {
-    this.data = bn.toArrayLike(Uint8Array);
-  }
-}
-
-export default MPI;
diff --git a/src/util.js b/src/util.js
index 431d4245..fe9991fd 100644
--- a/src/util.js
+++ b/src/util.js
@@ -194,9 +194,6 @@ export default {
 
   /**
    * Convert a Uint8Array to an MPI-formatted Uint8Array.
-   * Note: the output is **not** an MPI object.
-   * @see {@link module:type/mpi/MPI.fromUint8Array}
-   * @see {@link module:type/mpi/MPI.toUint8Array}
    * @param {Uint8Array} bin An array of 8-bit integers to convert
    * @returns {Uint8Array} MPI-formatted Uint8Array
    */
diff --git a/test/crypto/crypto.js b/test/crypto/crypto.js
index 63171ba1..c8f2c313 100644
--- a/test/crypto/crypto.js
+++ b/test/crypto/crypto.js
@@ -211,35 +211,24 @@ module.exports = () => describe('API functional testing', function() {
 
   describe('Sign and verify', function () {
     it('RSA', async function () {
-      return crypto.signature.sign(
-        1, 2, RSAPublicParams, RSAPrivateParams, data, await crypto.hash.digest(2, data)
-      ).then(async RSAsignedData => {
-        const RSAsignedDataMPI = new openpgp.MPI();
-        RSAsignedDataMPI.read(RSAsignedData);
-        return crypto.signature.verify(
-          1, 2, [RSAsignedDataMPI], RSAPublicParams, data, await crypto.hash.digest(2, data)
-        ).then(success => {
-          return expect(success).to.be.true;
-        });
-      });
+      const RSAsignedData = await crypto.signature.sign(
+        openpgp.enums.publicKey.rsaEncryptSign, openpgp.enums.hash.sha1, RSAPublicParams, RSAPrivateParams, data, await crypto.hash.digest(2, data)
+      );
+      const success = await crypto.signature.verify(
+        openpgp.enums.publicKey.rsaEncryptSign, openpgp.enums.hash.sha1, RSAsignedData, RSAPublicParams, data, await crypto.hash.digest(2, data)
+      );
+      return expect(success).to.be.true;
     });
 
     it('DSA', async function () {
-      return crypto.signature.sign(
-        17, 2, DSAPublicParams, DSAPrivateParams, data, await crypto.hash.digest(2, data)
-      ).then(async DSAsignedData => {
-        DSAsignedData = util.uint8ArrayToStr(DSAsignedData);
-        const DSAmsgMPIs = [];
-        DSAmsgMPIs[0] = new openpgp.MPI();
-        DSAmsgMPIs[1] = new openpgp.MPI();
-        DSAmsgMPIs[0].read(DSAsignedData.substring(0,34));
-        DSAmsgMPIs[1].read(DSAsignedData.substring(34,68));
-        return crypto.signature.verify(
-          17, 2, DSAmsgMPIs, DSAPublicParams, data, await crypto.hash.digest(2, data)
-        ).then(success => {
-          return expect(success).to.be.true;
-        });
-      });
+      const DSAsignedData = await crypto.signature.sign(
+        openpgp.enums.publicKey.dsa, openpgp.enums.hash.sha1, DSAPublicParams, DSAPrivateParams, data, await crypto.hash.digest(2, data)
+      );
+      const success = await crypto.signature.verify(
+        openpgp.enums.publicKey.dsa, openpgp.enums.hash.sha1, DSAsignedData, DSAPublicParams, data, await crypto.hash.digest(2, data)
+      );
+
+      return expect(success).to.be.true;
     });
   });
 
diff --git a/test/crypto/rsa.js b/test/crypto/rsa.js
index 3719f702..67558f2a 100644
--- a/test/crypto/rsa.js
+++ b/test/crypto/rsa.js
@@ -39,8 +39,7 @@ module.exports = () => (!native ? describe.skip : describe)('basic RSA cryptogra
     const { n, e, d, p, q, u } = { ...publicParams, ...privateParams };
     const message = await openpgp.crypto.generateSessionKey('aes256');
     const encrypted = await openpgp.crypto.publicKey.rsa.encrypt(message, n, e);
-    const result = new openpgp.MPI(encrypted);
-    const decrypted = await openpgp.crypto.publicKey.rsa.decrypt(result.toUint8Array(), n, e, d, p, q, u);
+    const decrypted = await openpgp.crypto.publicKey.rsa.decrypt(encrypted, n, e, d, p, q, u);
     expect(decrypted).to.deep.equal(message);
   });
 
diff --git a/test/general/biginteger.js b/test/general/biginteger.js
index 29171198..befa6347 100644
--- a/test/general/biginteger.js
+++ b/test/general/biginteger.js
@@ -155,14 +155,4 @@ module.exports = () => describe('BigInteger interface', function() {
     const expected = nBN.testn(5) ? 1 : 0;
     expect(n.getBit(i) === expected).to.be.true;
   });
-
-  describe('MPI and BigInteger conversions', function() {
-    it('MPI to/from BigInteger is correct', async function() {
-      const input = '417653931840771530406225971293556769925351769207235721650257629558293828796031115397206059067934284452829611906818956352854418342467914729341523414945427019410284762464062112274326172407819051167058569790660930309496043254270888417520676082271432948852231332576271876251597199882908964994070268531832274431027';
-      const n = new BigInteger(input);
-      const mpi = new openpgp.MPI(n);
-
-      expect((await mpi.toBigInteger()).equal(n)).to.be.true;
-    });
-  });
 });
diff --git a/test/general/signature.js b/test/general/signature.js
index b007a3c2..010ad1a2 100644
--- a/test/general/signature.js
+++ b/test/general/signature.js
@@ -656,7 +656,7 @@ WPVMYDzj6X7I1A+nWeNiPlp2PoUUUvdCLisY1aU1wyTJa7wBsLARsrhXk5/R1pQt
 Blk+CJ7ytHy6En8542bB/yC+Z9/zWbVuhg==
 =jmT1
 -----END PGP PUBLIC KEY BLOCK-----`;
-      
+
     const msg_sig_expired =
     ['-----BEGIN PGP MESSAGE-----',
       'Comment: GPGTools - https://gpgtools.org',
@@ -1609,21 +1609,17 @@ hkJiXopCSWKSlQInL1devkJJUWJmTmZeugJYlpdLAagQJM0JpsCqIQZwKgAA
     const privKey2 = await openpgp.readArmoredKey(priv_key_arm2);
     await privKey2.decrypt('hello world');
 
-    const opt = {rsaBits: 512, userIds: { name:'test', email:'a@b.com' }, passphrase: null};
+    const opt = { rsaBits: 512, userIds: { name:'test', email:'a@b.com' }, passphrase: null };
     if (openpgp.util.getWebCryptoAll()) { opt.rsaBits = 2048; } // webkit webcrypto accepts minimum 2048 bit keys
-    return openpgp.generateKey(opt).then(function(gen) {
-      const generatedKey = gen.key;
-      return msg.signDetached([generatedKey, privKey2]).then(detachedSig => {
-        return msg.verifyDetached(detachedSig, [generatedKey.toPublic(), pubKey2]).then(async result => {
-          expect(await result[0].verified).to.be.true;
-          expect(await result[1].verified).to.be.true;
-        });
-      });
-    });
+    const { key: generatedKey } = await openpgp.generateKey(opt);
+    const detachedSig = await msg.signDetached([generatedKey, privKey2]);
+    const result = await msg.verifyDetached(detachedSig, [generatedKey.toPublic(), pubKey2]);
+    expect(await result[0].verified).to.be.true;
+    expect(await result[1].verified).to.be.true;
   });
 
   it('Sign message with key without password', function() {
-    const opt = {userIds: { name:'test', email:'a@b.com' }, passphrase: null};
+    const opt = { userIds: { name:'test', email:'a@b.com' }, passphrase: null };
     return openpgp.generateKey(opt).then(function(gen) {
       const key = gen.key;
       let message = openpgp.Message.fromText('hello world');
diff --git a/test/general/streaming.js b/test/general/streaming.js
index abbb06dc..4814d2fe 100644
--- a/test/general/streaming.js
+++ b/test/general/streaming.js
@@ -971,4 +971,4 @@ module.exports = () => describe('Streaming', function() {
       expect(await openpgp.stream.readToEnd(decrypted.data)).to.deep.equal(plaintext);
     });
   }
-});
\ No newline at end of file
+});
diff --git a/test/general/x25519.js b/test/general/x25519.js
index 6a092009..2c1016e7 100644
--- a/test/general/x25519.js
+++ b/test/general/x25519.js
@@ -216,8 +216,8 @@ module.exports = () => (openpgp.config.ci ? describe.skip : describe)('X25519 Cr
     const util = openpgp.util;
     function testVector(vector) {
       const curve = new elliptic.Curve('ed25519');
-      const { publicKey } = openpgp.crypto.publicKey.nacl.sign.keyPair.fromSeed(openpgp.util.hexToUint8Array(vector.SECRET_KEY));
-      expect(publicKey).to.deep.equal(openpgp.util.hexToUint8Array(vector.PUBLIC_KEY));
+      const { publicKey } = openpgp.crypto.publicKey.nacl.sign.keyPair.fromSeed(util.hexToUint8Array(vector.SECRET_KEY));
+      expect(publicKey).to.deep.equal(util.hexToUint8Array(vector.PUBLIC_KEY));
       const data = util.strToUint8Array(vector.MESSAGE);
       const privateParams = {
         seed: util.hexToUint8Array(vector.SECRET_KEY)
@@ -226,17 +226,14 @@ module.exports = () => (openpgp.config.ci ? describe.skip : describe)('X25519 Cr
         oid: new openpgp.OID(curve.oid),
         Q: util.hexToUint8Array('40' + vector.PUBLIC_KEY)
       };
-      const msg_MPIs = [
-        new openpgp.MPI(util.uint8ArrayToStr(util.hexToUint8Array(vector.SIGNATURE.R).reverse())),
-        new openpgp.MPI(util.uint8ArrayToStr(util.hexToUint8Array(vector.SIGNATURE.S).reverse()))
-      ];
+      const R = util.hexToUint8Array(vector.SIGNATURE.R);
+      const S = util.hexToUint8Array(vector.SIGNATURE.S);
       return Promise.all([
-        signature.sign(22, undefined, publicParams, privateParams, undefined, data).then(signed => {
-          const len = (((signed[0] << 8) | signed[1]) + 7) / 8;
-          expect(util.hexToUint8Array(vector.SIGNATURE.R)).to.deep.eq(signed.slice(2, 2 + len));
-          expect(util.hexToUint8Array(vector.SIGNATURE.S)).to.deep.eq(signed.slice(4 + len));
+        signature.sign(22, undefined, publicParams, privateParams, undefined, data).then(({ r, s }) => {
+          expect(R).to.deep.eq(r);
+          expect(S).to.deep.eq(s);
         }),
-        signature.verify(22, undefined, msg_MPIs, publicParams, undefined, data).then(result => {
+        signature.verify(22, undefined, { r: R, s: S }, publicParams, undefined, data).then(result => {
           expect(result).to.be.true;
         })
       ]);