Fix context verification with expectSigned: true: throw on invalid …

…context

Verification wouldn't throw if the OpenPGP signature was valid
but the context was not matching.

This bug had no actual impact since `expectSigned` isn't used by any app yet.

lib/message/decrypt.js

@@ -30,7 +30,7 @@ export default async function decryptMessage({
         }
 
         const decryptionResult = await decrypt(sanitizedOptions);
-        const verificationResult = handleVerificationResult(decryptionResult, context);
+        const verificationResult = handleVerificationResult(decryptionResult, context, options.expectSigned);
 
         let verified = verificationResult.then((result) => result.verified);
         let verifiedSignatures = verificationResult.then((result) => result.signatures);

lib/message/verify.d.ts

@@ -35,7 +35,8 @@ export function verifyMessage<DataType extends Data, FormatType extends VerifyOp
 >;
 export function handleVerificationResult<DataType extends Data>(
     verificationResult: openpgp_VerifyMessageResult<DataType>,
-    context: ContextVerificationOptions
+    context?: ContextVerificationOptions,
+    expectSigned?: boolean
 ): Promise<VerifyMessageResult<DataType>>;
 
 export interface VerifyCleartextOptionsPmcrypto extends Omit<VerifyOptions, 'message' | 'signature' | 'format'> {

lib/message/verify.js

@@ -18,6 +18,7 @@ const { NOT_SIGNED, SIGNED_AND_VALID, SIGNED_AND_INVALID } = VERIFICATION_STATUS
  *           signature: Promise<openpgp.signature.Signature>
  *         }
  * @param {Object} context - context verification options
+ * @param {Boolean} expectSigned - whether a valid signature is expected; it causes the function to throw otherwise
  * @returns {{
  *     data: Uint8Array|string|ReadableStream|NodeStream - message data,
  *     verified: constants.VERIFICATION_STATUS - message verification status,
@@ -26,7 +27,7 @@ const { NOT_SIGNED, SIGNED_AND_VALID, SIGNED_AND_INVALID } = VERIFICATION_STATUS
  *     errors: Error[]|undefined - verification errors if all signatures are invalid
  * }}
  */
-export async function handleVerificationResult(verificationResult, context) {
+export async function handleVerificationResult(verificationResult, context, expectSigned) {
     const { data, signatures: sigsInfo } = verificationResult;
     const signatures = [];
     const errors = [];
@@ -52,7 +53,7 @@ export async function handleVerificationResult(verificationResult, context) {
                 if (!context || isValidSignatureContext(context, verifiedSigPacket)) {
                     verificationStatus = SIGNED_AND_VALID;
                 } else {
-                    errors.push(new ContextError());
+                    errors.push(new ContextError('context verification error'));
                 }
 
                 if (!signatureTimestamp) {
@@ -63,6 +64,11 @@ export async function handleVerificationResult(verificationResult, context) {
         }
     }
 
+    if (expectSigned && verificationStatus !== SIGNED_AND_VALID) {
+        // this is primarily intended to throw context error, which isn't checked by OpenPGP.js
+        throw errors[0];
+    }
+
     return {
         data,
         verified: verificationStatus,
@@ -106,7 +112,7 @@ export async function verifyMessage({
     };
 
     const verificationResult = await verify(sanitizedOptions);
-    return handleVerificationResult(verificationResult, context);
+    return handleVerificationResult(verificationResult, context, options.expectSigned);
 }
 
 /**
@@ -131,5 +137,5 @@ export async function verifyCleartextMessage({ cleartextMessage, date = serverTi
     const sanitizedOptions = { ...options, date, message: cleartextMessage };
 
     const verificationResult = await verify(sanitizedOptions);
-    return handleVerificationResult(verificationResult);
+    return handleVerificationResult(verificationResult, undefined, options.expectSigned);
 }

test/message/context.spec.ts

@@ -34,6 +34,15 @@ describe('context', () => {
             context: { value: 'unexpected-context', required: true }
         });
 
+        // verificationWrongContext with `expectSigned`
+        await expect(verifyMessage({
+            textData,
+            signature: await readSignature({ armoredSignature }),
+            verificationKeys: [publicKey],
+            context: { value: 'unexpected-context', required: true },
+            expectSigned: true
+        })).to.be.rejectedWith(ContextError);
+
         const verificationMissingContext = await verifyMessage({
             textData,
             signature: await readSignature({ armoredSignature }),