Add config parameter to top-level functions (#1241)

Refactor functions to take the configuration as a parameter.

This allows setting a config option for a single function call, whereas
setting `openpgp.config` could lead to concurrency-related issues when
multiple async function calls are made at the same time.

`openpgp.config` is used as default for unset config values in top-level
functions.
`openpgp.config` is used as default config object in low-level functions
(i.e., when calling a low-level function, it may be required to pass
`{ ...openpgp.config, modifiedConfig: modifiedValue }`).

Also,

- remove `config.rsaBlinding`: blinding is now always applied to RSA decryption
- remove `config.debug`: debugging mode can be enabled by setting
  `process.env.NODE_ENV = 'development'`
- remove `config.useNative`: native crypto is always used when available

src/packet/symmetrically_encrypted_data.js

@@ -25,7 +25,6 @@
  */
 
 import stream from 'web-stream-tools';
-import config from '../config';
 import crypto from '../crypto';
 import enums from '../enums';
 import util from '../util';
@@ -35,6 +34,7 @@ import {
   OnePassSignaturePacket,
   SignaturePacket
 } from '../packet';
+import defaultConfig from '../config';
 
 /**
  * Implementation of the Symmetrically Encrypted Data Packet (Tag 9)
@@ -63,11 +63,6 @@ class SymmetricallyEncryptedDataPacket {
      * @type {PacketList}
      */
     this.packets = null;
-    /**
-     * When true, decrypt fails if message is not integrity protected
-     * @see module:config.ignoreMdcError
-     */
-    this.ignoreMdcError = config.ignoreMdcError;
   }
 
   read(bytes) {
@@ -83,12 +78,14 @@ class SymmetricallyEncryptedDataPacket {
    * See {@link https://tools.ietf.org/html/rfc4880#section-9.2|RFC 4880 9.2} for algorithms.
    * @param {module:enums.symmetric} sessionKeyAlgorithm Symmetric key algorithm to use
    * @param {Uint8Array} key    The key of cipher blocksize length to be used
+   * @param {Object}     config (optional) full configuration, defaults to openpgp.config
+
    * @throws {Error} if decryption was not successful
    * @async
    */
-  async decrypt(sessionKeyAlgorithm, key, streaming) {
+  async decrypt(sessionKeyAlgorithm, key, streaming, config = defaultConfig) {
     // If MDC errors are not being ignored, all missing MDC packets in symmetrically encrypted data should throw an error
-    if (!this.ignoreMdcError) {
+    if (!config.ignoreMdcError) {
       throw new Error('Decryption failed due to missing MDC.');
     }
 
@@ -111,15 +108,16 @@ class SymmetricallyEncryptedDataPacket {
    * See {@link https://tools.ietf.org/html/rfc4880#section-9.2|RFC 4880 9.2} for algorithms.
    * @param {module:enums.symmetric} sessionKeyAlgorithm Symmetric key algorithm to use
    * @param {Uint8Array} key    The key of cipher blocksize length to be used
+   * @param {Object}     config (optional) full configuration, defaults to openpgp.config
    * @throws {Error} if encryption was not successful
    * @async
    */
-  async encrypt(algo, key) {
+  async encrypt(algo, key, streaming, config = defaultConfig) {
     const data = this.packets.write();
 
     const prefix = await crypto.getPrefixRandom(algo);
-    const FRE = await crypto.cfb.encrypt(algo, key, prefix, new Uint8Array(crypto.cipher[algo].blockSize));
-    const ciphertext = await crypto.cfb.encrypt(algo, key, data, FRE.subarray(2));
+    const FRE = await crypto.cfb.encrypt(algo, key, prefix, new Uint8Array(crypto.cipher[algo].blockSize), config);
+    const ciphertext = await crypto.cfb.encrypt(algo, key, data, FRE.subarray(2), config);
     this.encrypted = util.concat([FRE, ciphertext]);
   }
 }