Throw error for unsupported key algorithms.

Throw error from `AsymmetricKey.getAlgorithm()` if an unsupported
encoded key algorithm is found. This may be indirectly called from the
constructor and other functions.

Author: davidlehn

CHANGELOG.md

@@ -1,5 +1,12 @@
 # webkms-client ChangeLog
 
+## 14.1.2 - 2024-xx-xx
+
+### Changed
+- Throw error from `AsymmetricKey.getAlgorithm()` if an unsupported encoded key
+  algorithm is found. This may be indirectly called from the constructor and
+  other functions.
+
 ## 14.1.1 - 2024-07-10
 
 ### Added

lib/AsymmetricKey.js

@@ -130,7 +130,8 @@ export class AsymmetricKey {
   }
 
   /**
-   * Gets the JOSE algorithm from a key description.
+   * Gets the JOSE algorithm from a key description. Throws error if the
+   * encoded key algorithm is not supported.
    *
    * @param {object} options - The options to use.
    * @param {object} options.keyDescription - A key description.
@@ -142,7 +143,12 @@ export class AsymmetricKey {
     // presently all supported key types will have a base58-multikey-header
     // value that is only 4 characters long
     const prefix = publicKeyMultibase?.slice(0, 4);
-    return BASE58_MULTIKEY_HEADER_TO_JOSE.get(prefix);
+    const algorithm = BASE58_MULTIKEY_HEADER_TO_JOSE.get(prefix);
+    if(!algorithm) {
+      throw new Error(
+        `Unsupported key description public key prefix: "${prefix}".`);
+    }
+    return algorithm;
   }
 
   /**

tests/20-AsymmetricKey.spec.js

@@ -18,6 +18,12 @@ const keys = new Map([
   ['secp256k1', 'did:key:zQ3shokFTS3brHcDQrn82RUDfCZESWL1ZdCEJwekUDPQiYBme']
 ]);
 
+const badKeys = new Map([
+  // key from a test with unkonwn 'zUC6' prefix
+  // eslint-disable-next-line
+  ['Bls12381G2', 'did:key:zUC6zwkczByHEDfap8UJdBwLDeiTYn2xUBq5AhYDnH3Actf9RgdvVF3Rqc2DaYh8j6JysZ6HLidVxM2Y2AhTtM7a5GefA2DGv6JJuSaTJ7ov1jtCnQLmAFYJoovhdzj2kivX9ev'],
+]);
+
 describe('AsymmetricKey API', () => {
   describe('should create key from keyDescription', () => {
     for(const [keyType, did] of keys) {
@@ -38,4 +44,24 @@ describe('AsymmetricKey API', () => {
       });
     }
   });
+  describe('should fail for bad keys', () => {
+    for(const [keyType, did] of badKeys) {
+      it(`key type ${keyType}`, async () => {
+        let error;
+        let key;
+        try {
+          const keyDescription = {
+            id: did,
+            type: keyType,
+            publicKeyMultibase: did.slice(8)
+          };
+          key = new AsymmetricKey({keyDescription});
+        } catch(e) {
+          error = e;
+        }
+        should.exist(error, 'Expected error to exist');
+        should.not.exist(key, 'Expected key to not exist');
+      });
+    }
+  });
 });