Remove unused enums.symmetric.plaintext

This special cipher value can be relevant for unencrypted private keys:
https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#section-12.2.1 .
However, it is no longer used internally, and on the contrary it could cause
confusion on SKESK decryption, where "random" cipher algos are returned in case
of wrong password.

This change also fixes a flaky test on password-based decryption, caused by the
PKESK v6 changes which add support for `null` cipher algos. The code did not
distinguish between a `null` and a `0` (plaintext) algo identifier, and would
break when the latter was returned on SKESK decryption.

openpgp.d.ts

@@ -181,7 +181,7 @@ export function generateSessionKey(options: { encryptionKeys: MaybeArray<PublicK
 export function encryptSessionKey(options: EncryptSessionKeyOptions & { format?: 'armored' }): Promise<string>;
 export function encryptSessionKey(options: EncryptSessionKeyOptions & { format: 'binary' }): Promise<Uint8Array>;
 export function encryptSessionKey(options: EncryptSessionKeyOptions & { format: 'object' }): Promise<Message<Data>>;
-export function decryptSessionKeys<T extends MaybeStream<Data>>(options: { message: Message<T>, decryptionKeys?: MaybeArray<PrivateKey>, passwords?: MaybeArray<string>, date?: Date, config?: PartialConfig }): Promise<SessionKey[]>;
+export function decryptSessionKeys<T extends MaybeStream<Data>>(options: { message: Message<T>, decryptionKeys?: MaybeArray<PrivateKey>, passwords?: MaybeArray<string>, date?: Date, config?: PartialConfig }): Promise<DecryptedSessionKey[]>;
 
 export function readMessage<T extends MaybeStream<string>>(options: { armoredMessage: T, config?: PartialConfig }): Promise<Message<T>>;
 export function readMessage<T extends MaybeStream<Uint8Array>>(options: { binaryMessage: T, config?: PartialConfig }): Promise<Message<T>>;
@@ -578,6 +578,11 @@ export interface SessionKey {
   aeadAlgorithm?: enums.aeadNames;
 }
 
+export interface DecryptedSessionKey {
+  data: Uint8Array;
+  algorithm: enums.symmetricNames | null; // `null` if the session key is associated with a SEIPDv2 packet
+}
+
 export interface ReasonForRevocation { flag?: enums.reasonForRevocation, string?: string }
 
 interface EncryptOptions {
@@ -843,9 +848,8 @@ export namespace enums {
     brainpoolP512r1 = 'brainpoolP512r1'
   }
 
-  export type symmetricNames = 'plaintext' | 'idea' | 'tripledes' | 'cast5' | 'blowfish' | 'aes128' | 'aes192' | 'aes256' | 'twofish';
+  export type symmetricNames = 'idea' | 'tripledes' | 'cast5' | 'blowfish' | 'aes128' | 'aes192' | 'aes256' | 'twofish';
   enum symmetric {
-    plaintext = 0,
     idea = 1,
     tripledes = 2,
     cast5 = 3,

src/enums.js

@@ -140,7 +140,6 @@ export default {
    * @readonly
    */
   symmetric: {
-    plaintext: 0,
     /** Not implemented! */
     idea: 1,
     tripledes: 2,

test/general/openpgp.js

@@ -2250,6 +2250,71 @@ XfA3pqV4mTzF
     });
   });
 
+  describe('decryptSessionKeys - unit tests', function() {
+    it('should decrypt message with two SKESKs where the wrong password returns a symmetric algo equal to 0', async function () {
+      // SKESK packets do not have an intrisic integrity check, and the session key must be used to check its validity.
+      // This message is such that when the password is used to try and decrypt the first (mismatching) SKESK, the result returns a '0' byte for
+      // the session key algo. This corresponds to the 'plaintext' algo identifier (https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#section-12.2.1),
+      // now removed from OpenPGP.js .
+      // This test guards against regressions caused by mishandling this value on SKESK decryption.
+      const message = await openpgp.readMessage({ armoredMessage:`-----BEGIN PGP MESSAGE-----
+
+wy4ECQMIf6HA/a6XkOAAlaU1z+uVfU5kmHmqNqahQH859nAMresQ6w1uIjsL
+ZE5bwy4ECQMIKVfCf+GWBesA5KFPuIDa6kLLn/AvEgbCi5DOg2xdIf73SNSN
+Tqy7nfex0sANAVtHHRkHVTRVTVa3MFjjiWeBEDtnfyVMntWJ21ihrIU9eb9p
+qS7UljZZ0u++xSWclU2IGBXCIdO0wLuS6hYk3q5OFexWj8OIoYJX88nkA2iW
+5xyGd9EFRWVsR4CREt8lwrIE2t/h8XpRlhJmY6Iefg8+2DeN8vDdhNs/B02o
+0zAE0hF+3xvwZTLi4hDrhBZEgBedPaeX4jlmDc3qzh2wlgV/Mq/FUakYfSLl
+bc1PCpfqkLZSuCfv4eoTrWohWi9lS/pRXY9hzzHtlnjo6w==
+-----END PGP MESSAGE-----` });
+      const sessionKeys = await openpgp.decryptSessionKeys({ message, passwords: 'I am another password' });
+      expect(sessionKeys).to.have.length(1); // first SKESK dropped due to '0' being treated as invalid algo identifier
+      expect(sessionKeys[0].algorithm).to.equal('aes256');
+
+      // decrypt() used to fail on this type of input
+      const decrypted = await openpgp.decrypt({ message, passwords: 'I am another password', format: 'binary' });
+      expect(decrypted.data).to.deep.equal(
+        util.hexToUint8Array('e280872009d699e0b5bae18ba1e28c86d280d184e1b888e1a8b3e28ab7e0afa8e0b98be283bde28db5e1b1afd48de1b5b2e280a7e199b0e1a487e185afd3a1e18ca5e0bfb4e28892e19e98e29bb8e29594e0baaae0b681e1929af09f9882f09f9897f09f9882f09f98abf09f988ff09f98b6f09f98bcf09f98bcf09f9981f09f9982e2808720090d0aed959ceab5adec96b42feca1b0ec84a0eba790')
+      );
+      expect(decrypted.signatures.length).to.equal(0);
+    });
+
+    it('should decrypt PKESK v6 and return a null symmetric algorithm', async function() {
+      // test vector https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#appendix-A.8
+      const armoredMessage = `-----BEGIN PGP MESSAGE-----
+
+wV0GIQYSyD8ecG9jCP4VGkF3Q6HwM3kOk+mXhIjR2zeNqZMIhRmHzxjV8bU/gXzO
+WgBM85PMiVi93AZfJfhK9QmxfdNnZBjeo1VDeVZheQHgaVf7yopqR6W1FT6NOrfS
+aQIHAgZhZBZTW+CwcW1g4FKlbExAf56zaw76/prQoN+bAzxpohup69LA7JW/Vp0l
+yZnuSj3hcFj0DfqLTGgr4/u717J+sPWbtQBfgMfG9AOIwwrUBqsFE9zW+f1zdlYo
+bhF30A+IitsxxA==
+-----END PGP MESSAGE-----`;
+
+      const privateKey = await openpgp.readKey({ armoredKey: `-----BEGIN PGP PRIVATE KEY BLOCK-----
+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+-----END PGP PRIVATE KEY BLOCK-----` });
+
+      const sessionKeys = await openpgp.decryptSessionKeys({
+        message: await openpgp.readMessage({ armoredMessage }),
+        decryptionKeys: privateKey
+      });
+
+      expect(sessionKeys).to.have.length(1);
+      expect(sessionKeys[0].algorithm).to.equal(null); // PKESK v6 does not include the algo info
+    });
+  });
+
   describe('encrypt, decrypt, sign, verify - integration tests', function() {
     let privateKey_2000_2008;
     let publicKey_2000_2008;