Validate parent fingerprint and master fingerprint for a given depth

MetaMask · Mar 7, 2023 · 0380556 · 0380556
1 parent 64e54b1
commit 0380556
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Showing 4 changed files with 137 additions and 4 deletions.
diff --git a/src/BIP44CoinTypeNode.test.ts b/src/BIP44CoinTypeNode.test.ts
@@ -80,7 +80,7 @@ describe('BIP44CoinTypeNode', () => {
       const options = {
         depth: 2,
         index: 0,
-        parentFingerprint: 0,
+        parentFingerprint: 1,
       };
 
       const inputs = [

diff --git a/src/BIP44Node.test.ts b/src/BIP44Node.test.ts
@@ -27,7 +27,7 @@ describe('BIP44Node', () => {
         privateKey,
         chainCode,
         depth: 2,
-        parentFingerprint: 0,
+        parentFingerprint: 1,
         index: 0,
       });
 
@@ -54,7 +54,7 @@ describe('BIP44Node', () => {
         privateKey,
         chainCode,
         depth: 2,
-        parentFingerprint: 0,
+        parentFingerprint: 1,
         index: 0,
       });
 

diff --git a/src/SLIP10Node.test.ts b/src/SLIP10Node.test.ts
@@ -325,6 +325,67 @@ describe('SLIP10Node', () => {
         'Invalid private key: Value is not a valid secp256k1 private key.',
       );
     });
+
+    it('throws if the depth is zero and the parent fingerprint is not zero', async () => {
+      await expect(
+        SLIP10Node.fromExtendedKey({
+          privateKey: new Uint8Array(32).fill(1),
+          chainCode: new Uint8Array(32).fill(1),
+          depth: 0,
+          parentFingerprint: 1,
+          index: 0,
+          curve: 'secp256k1',
+        }),
+      ).rejects.toThrow(
+        'Invalid parent fingerprint: The fingerprint of the root node must be 0. Received: "1".',
+      );
+    });
+
+    it('throws if the depth is not zero and the parent fingerprint is zero', async () => {
+      await expect(
+        SLIP10Node.fromExtendedKey({
+          privateKey: new Uint8Array(32).fill(1),
+          chainCode: new Uint8Array(32).fill(1),
+          depth: 1,
+          parentFingerprint: 0,
+          index: 0,
+          curve: 'secp256k1',
+        }),
+      ).rejects.toThrow(
+        'Invalid parent fingerprint: The fingerprint of a child node must not be 0. Received: "0".',
+      );
+    });
+
+    it('throws if the depth is >= 2 and the parent fingerprint is equal to the master fingerprint', async () => {
+      await expect(
+        SLIP10Node.fromExtendedKey({
+          privateKey: new Uint8Array(32).fill(1),
+          chainCode: new Uint8Array(32).fill(1),
+          depth: 2,
+          parentFingerprint: 1,
+          masterFingerprint: 1,
+          index: 0,
+          curve: 'secp256k1',
+        }),
+      ).rejects.toThrow(
+        'Invalid parent fingerprint: The fingerprint of a child node cannot be equal to the master fingerprint. Received: "1".',
+      );
+    });
+
+    it('throws if the depth is zero and the index is not zero', async () => {
+      await expect(
+        SLIP10Node.fromExtendedKey({
+          privateKey: new Uint8Array(32).fill(1),
+          chainCode: new Uint8Array(32).fill(1),
+          depth: 0,
+          parentFingerprint: 0,
+          index: 1,
+          curve: 'secp256k1',
+        }),
+      ).rejects.toThrow(
+        'Invalid index: The index of the root node must be 0. Received: "1".',
+      );
+    });
   });
 
   describe('fromDerivationPath', () => {

diff --git a/src/SLIP10Node.ts b/src/SLIP10Node.ts
@@ -161,7 +161,13 @@ export class SLIP10Node implements SLIP10NodeInterface {
     validateCurve(curve);
     validateBIP32Depth(depth);
     validateBIP32Index(index);
-    validateParentFingerprint(parentFingerprint);
+    validateRootIndex(index, depth);
+    validateParentFingerprint(parentFingerprint, depth);
+    validateMasterParentFingerprint(
+      masterFingerprint,
+      parentFingerprint,
+      depth,
+    );
 
     const curveObject = getCurveByName(curve);
 
@@ -436,9 +442,13 @@ export function validateBIP32Depth(depth: unknown): asserts depth is number {
  * integer `number`. Throws an error if validation fails.
  *
  * @param parentFingerprint - The parent fingerprint to validate.
+ * @param depth - The depth of the node to validate.
+ * @throws If the parent fingerprint is not a positive integer, or invalid for
+ * the current depth.
  */
 export function validateParentFingerprint(
   parentFingerprint: unknown,
+  depth: number,
 ): asserts parentFingerprint is number {
   if (!isValidInteger(parentFingerprint)) {
     throw new Error(
@@ -447,6 +457,68 @@ export function validateParentFingerprint(
       )}".`,
     );
   }
+
+  if (depth === 0 && parentFingerprint !== 0) {
+    throw new Error(
+      `Invalid parent fingerprint: The fingerprint of the root node must be 0. Received: "${String(
+        parentFingerprint,
+      )}".`,
+    );
+  }
+
+  if (depth > 0 && parentFingerprint === 0) {
+    throw new Error(
+      `Invalid parent fingerprint: The fingerprint of a child node must not be 0. Received: "${String(
+        parentFingerprint,
+      )}".`,
+    );
+  }
+}
+
+/**
+ * Validate that a given combination of master fingerprint and parent
+ * fingerprint is valid for the given depth.
+ *
+ * @param masterFingerprint - The master fingerprint to validate.
+ * @param parentFingerprint - The parent fingerprint to validate.
+ * @param depth - The depth of the node to validate.
+ * @throws If the combination of master fingerprint and parent fingerprint is
+ * invalid for the given depth.
+ */
+export function validateMasterParentFingerprint(
+  masterFingerprint: number | undefined,
+  parentFingerprint: number,
+  depth: number,
+) {
+  // The master fingerprint is optional.
+  if (!masterFingerprint) {
+    return;
+  }
+
+  if (depth >= 2 && masterFingerprint === parentFingerprint) {
+    throw new Error(
+      `Invalid parent fingerprint: The fingerprint of a child node cannot be equal to the master fingerprint. Received: "${String(
+        parentFingerprint,
+      )}".`,
+    );
+  }
+}
+
+/**
+ * Validate that the index is zero for the root node.
+ *
+ * @param index - The index to validate.
+ * @param depth - The depth of the node to validate.
+ * @throws If the index is not zero for the root node.
+ */
+export function validateRootIndex(index: number, depth: number) {
+  if (depth === 0 && index !== 0) {
+    throw new Error(
+      `Invalid index: The index of the root node must be 0. Received: "${String(
+        index,
+      )}".`,
+    );
+  }
 }
 
 type DeriveChildNodeArgs = {