Add compression support for the encrypt function

src/config/config.js

@@ -31,7 +31,7 @@ export default {
   /** @property {Integer} encryption_cipher Default encryption cipher {@link module:enums.symmetric} */
   encryption_cipher: enums.symmetric.aes256,
   /** @property {Integer} compression Default compression algorithm {@link module:enums.compression} */
-  compression: enums.compression.zip,
+  compression: enums.compression.uncompressed,
 
   /**
    * Use Authenticated Encryption with Additional Data (AEAD) protection for symmetric encryption.

src/message.js

@@ -451,6 +451,26 @@ Message.prototype.sign = async function(privateKeys=[], signature=null) {
   return new Message(packetlist);
 };
 
+/**
+ * Compresses the message (the literal and -if signed- signature data packets of the message)
+ * @param  {module:enums.compression}   compression     compression algorithm to be used
+ * @return {module:message~Message}       new message with signed content
+ */
+Message.prototype.compress = function(compression) {
+  if (compression === enums.compression.uncompressed) {
+    return this;
+  }
+
+  const compressed = new packet.Compressed();
+  compressed.packets = this.packets;
+  compressed.algorithm = enums.read(enums.compression, compression);
+
+  const packetList = new packet.List();
+  packetList.push(compressed);
+
+  return new Message(packetList);
+};
+
 /**
  * Create a detached signature for the message (the literal data packet of the message)
  * @param  {Array<module:key~Key>}           privateKey private keys with decrypted secret key data for signing

src/openpgp.js

@@ -192,6 +192,7 @@ export function decryptKey({ privateKey, passphrase }) {
  * @param  {String|Array<String>} passwords   (optional) array of passwords or a single password to encrypt the message
  * @param  {Object} sessionKey                (optional) session key in the form: { data:Uint8Array, algorithm:String }
  * @param  {String} filename                  (optional) a filename for the literal data packet
+ * @param  {Boolean} compression              (optional) which compression algorithm to compress the message with, defaults to what is specified in config
  * @param  {Boolean} armor                    (optional) if the return values should be ascii armored or the message/signature objects
  * @param  {Boolean} detached                 (optional) if the signature should be detached (if true, signature will be added to returned object)
  * @param  {Signature} signature              (optional) a detached signature to add to the encrypted message
@@ -202,7 +203,7 @@ export function decryptKey({ privateKey, passphrase }) {
  *                                                message: full Message object if 'armor' is false, signature: detached signature if 'detached' is true}
  * @static
  */
-export function encrypt({ data, publicKeys, privateKeys, passwords, sessionKey, filename, armor=true, detached=false, signature=null, returnSessionKey=false, wildcard=false}) {
+export function encrypt({ data, publicKeys, privateKeys, passwords, sessionKey, filename, compression=config.compression, armor=true, detached=false, signature=null, returnSessionKey=false, wildcard=false}) {
   checkData(data); publicKeys = toArray(publicKeys); privateKeys = toArray(privateKeys); passwords = toArray(passwords);
 
   if (!nativeAEAD() && asyncProxy) { // use web worker if web crypto apis are not supported
@@ -223,6 +224,7 @@ export function encrypt({ data, publicKeys, privateKeys, passwords, sessionKey,
         message = await message.sign(privateKeys, signature);
       }
     }
+    message = message.compress(compression);
     return message.encrypt(publicKeys, passwords, sessionKey, wildcard);
 
   }).then(encrypted => {

src/packet/compressed.js

@@ -88,7 +88,7 @@ Compressed.prototype.write = function () {
     this.compress();
   }
 
-  return util.concatUint8Array(new Uint8Array([enums.write(enums.compression, this.algorithm)]), this.compressed);
+  return util.concatUint8Array([new Uint8Array([enums.write(enums.compression, this.algorithm)]), this.compressed]);
 };