Pad SDK browser Import Keys

packages/api-key-stamper/src/__tests__/elliptic-curves-test.ts

@@ -0,0 +1,80 @@
+import { test, expect } from "@jest/globals";
+import { pointDecode } from "../tink/elliptic_curves";
+import {
+  uint8ArrayFromHexString,
+  uint8ArrayToHexString,
+} from "@turnkey/encoding";
+
+test("pointDecode -> uncompressed invalid", async function () {
+  // Invalid uncompressed key (the last byte has been changed)
+  const uncompPubKey =
+    "0400d2eb47be2006c29db5fe9941dd686d19ddeea85a0328894f08091f6b5be9b366c4872345594c12a7f7c47c62dd8074542934820fce5ee0ddc55d6d1d8dd313";
+  expect(() => pointDecode(uint8ArrayFromHexString(uncompPubKey))).toThrow(
+    "invalid uncompressed x and y coordinates"
+  );
+});
+
+test("pointDecode -> uncompressed valid", async function () {
+  // Valid uncompressed public key with 00 as the first bit (test against 'x' field of JWK getting truncated)
+  const uncompPubKey =
+    "0400d2eb47be2006c29db5fe9941dd686d19ddeea85a0328894f08091f6b5be9b366c4872345594c12a7f7c47c62dd8074542934820fce5ee0ddc55d6d1d8dd312";
+  const jwk = pointDecode(uint8ArrayFromHexString(uncompPubKey));
+  expect(jwk.x).toBeDefined();
+  expect(jwk.y).toBeDefined();
+
+  // Convert x value to make sure it matches first half of uncompressed key WITHOUT truncating the first 0 bit
+  let xString: string = jwk.x !== undefined ? jwk.x : "_";
+  let xBytes = new Uint8Array(base64urlToBuffer(xString));
+  let xHex = uint8ArrayToHexString(xBytes);
+  expect(xHex).toBe(uncompPubKey.substring(2, 66));
+
+  // Convert y value to make sure it's the same as second half of uncompressed key
+  let yString: string = jwk.y !== undefined ? jwk.y : "_";
+  let yBytes = new Uint8Array(base64urlToBuffer(yString));
+  let yHex = uint8ArrayToHexString(yBytes);
+  expect(yHex).toBe(uncompPubKey.substring(66, 130));
+});
+
+test("pointDecode -> compressed", async function () {
+  // Valid compressed public key with 00 as the first bit (test against 'x' field of JWK getting truncated)
+  const uncompPubKey =
+    "0400d2eb47be2006c29db5fe9941dd686d19ddeea85a0328894f08091f6b5be9b366c4872345594c12a7f7c47c62dd8074542934820fce5ee0ddc55d6d1d8dd312";
+  // corresponding compressed public key
+  const compPubKey =
+    "0200d2eb47be2006c29db5fe9941dd686d19ddeea85a0328894f08091f6b5be9b3";
+
+  const jwk = pointDecode(uint8ArrayFromHexString(compPubKey));
+  expect(jwk.x).toBeDefined();
+  expect(jwk.y).toBeDefined();
+
+  // Convert x value to make sure it matches first half of uncompressed key WITHOUT truncating the first 0 bit
+  let xString: string = jwk.x !== undefined ? jwk.x : "_";
+  let xBytes = new Uint8Array(base64urlToBuffer(xString));
+  let xHex = uint8ArrayToHexString(xBytes);
+  expect(xHex).toBe(uncompPubKey.substring(2, 66));
+
+  // Convert y value to make sure it's the same as second half of uncompressed key
+  let yString: string = jwk.y !== undefined ? jwk.y : "_";
+  let yBytes = new Uint8Array(base64urlToBuffer(yString));
+  let yHex = uint8ArrayToHexString(yBytes);
+  expect(yHex).toBe(uncompPubKey.substring(66, 130));
+});
+
+// Convert base64 url encoded string to an array -- used here to test that output pads correctly and doesn't get truncated
+function base64urlToBuffer(baseurl64String: string): ArrayBuffer {
+  // Base64url to Base64
+  const padding = "==".slice(0, (4 - (baseurl64String.length % 4)) % 4);
+  const base64String =
+    baseurl64String.replace(/-/g, "+").replace(/_/g, "/") + padding;
+
+  // Base64 to binary string
+  const str = atob(base64String);
+
+  // Binary string to buffer
+  const buffer = new ArrayBuffer(str.length);
+  const byteView = new Uint8Array(buffer);
+  for (let i = 0; i < str.length; i++) {
+    byteView[i] = str.charCodeAt(i);
+  }
+  return buffer;
+}

packages/api-key-stamper/src/index.ts

@@ -78,3 +78,7 @@ export class ApiKeyStamper {
     };
   }
 }
+
+import { pointDecode } from "./tink/elliptic_curves";
+
+export { pointDecode };

packages/api-key-stamper/src/tink/elliptic_curves.ts

@@ -1,6 +1,8 @@
 /**
  * Code modified from https://github.com/google/tink/blob/6f74b99a2bfe6677e3670799116a57268fd067fa/javascript/subtle/elliptic_curves.ts
  * - The implementation of integerToByteArray has been modified to augment the resulting byte array to a certain length.
+ * - The implementation of PointDecode has been modified to decode both compressed and uncompressed points by checking for correct format
+ * - Methoed isP256CurvePoint added to check whether an uncompressed point is valid
  *
  * @license
  * Copyright 2020 Google LLC
@@ -136,35 +138,86 @@ function getY(x: bigint, lsb: boolean): bigint {
 }
 
 /**
- * Decodes a public key in _compressed_ format.
+ *
+ * Given x and y coordinates of a JWK, checks whether these are valid points on
+ * the P-256 elliptic curve.
+ *
+ * P-256 only
+ *
+ * @param x x-coordinate
+ * @param y y-coordinate
+ * @return boolean validity
+ */
+function isP256CurvePoint(x: bigint, y: bigint): boolean {
+  const p = getModulus();
+  const a = p - BigInt(3);
+  const b = getB();
+  const rhs = ((x * x + a) * x + b) % p;
+  const lhs = y ** BigInt(2) % p;
+  return lhs === rhs;
+}
+
+/**
+ * Decodes a public key in _compressed_ OR _uncompressed_ format.
  * Augmented to ensure that the x and y components are padded to fit 32 bytes.
  *
  * P-256 only
  */
 export function pointDecode(point: Uint8Array): JsonWebKey {
   const fieldSize = fieldSizeInBytes();
-
-  if (point.length !== 1 + fieldSize) {
-    throw new Error("compressed point has wrong length");
-  }
-  if (point[0] !== 2 && point[0] !== 3) {
-    throw new Error("invalid format");
+  const compressedLength = fieldSize + 1;
+  const uncompressedLength = 2 * fieldSize + 1;
+  if (
+    point.length !== compressedLength &&
+    point.length !== uncompressedLength
+  ) {
+    throw new Error(
+      "Invalid length: point is not in compressed or uncompressed format"
+    );
   }
-  const lsb = point[0] === 3; // point[0] must be 2 (false) or 3 (true).
-  const x = byteArrayToInteger(point.subarray(1, point.length));
-  const p = getModulus();
-  if (x < BigInt(0) || x >= p) {
-    throw new Error("x is out of range");
+  // Decodes point if its length and first bit match the compressed format
+  if ((point[0] === 2 || point[0] === 3) && point.length == compressedLength) {
+    const lsb = point[0] === 3; // point[0] must be 2 (false) or 3 (true).
+    const x = byteArrayToInteger(point.subarray(1, point.length));
+    const p = getModulus();
+    if (x < BigInt(0) || x >= p) {
+      throw new Error("x is out of range");
+    }
+    const y = getY(x, lsb);
+    const result: JsonWebKey = {
+      kty: "EC",
+      crv: "P-256",
+      x: Bytes.toBase64(integerToByteArray(x, 32), /* websafe */ true),
+      y: Bytes.toBase64(integerToByteArray(y, 32), /* websafe */ true),
+      ext: true,
+    };
+    return result;
+    // Decodes point if its length and first bit match the uncompressed format
+  } else if (point[0] === 4 && point.length == uncompressedLength) {
+    const x = byteArrayToInteger(point.subarray(1, fieldSize + 1));
+    const y = byteArrayToInteger(
+      point.subarray(fieldSize + 1, 2 * fieldSize + 1)
+    );
+    const p = getModulus();
+    if (
+      x < BigInt(0) ||
+      x >= p ||
+      y < BigInt(0) ||
+      y >= p ||
+      !isP256CurvePoint(x, y)
+    ) {
+      throw new Error("invalid uncompressed x and y coordinates");
+    }
+    const result: JsonWebKey = {
+      kty: "EC",
+      crv: "P-256",
+      x: Bytes.toBase64(integerToByteArray(x, 32), /* websafe */ true),
+      y: Bytes.toBase64(integerToByteArray(y, 32), /* websafe */ true),
+      ext: true,
+    };
+    return result;
   }
-  const y = getY(x, lsb);
-  const result: JsonWebKey = {
-    kty: "EC",
-    crv: "P-256",
-    x: Bytes.toBase64(integerToByteArray(x, 32), /* websafe */ true),
-    y: Bytes.toBase64(integerToByteArray(y, 32), /* websafe */ true),
-    ext: true,
-  };
-  return result;
+  throw new Error("invalid format");
 }
 
 /**

packages/encoding/src/__tests__/index-test.ts

@@ -94,6 +94,22 @@ test("uint8ArrayFromHexString", async function () {
   expect(() => {
     uint8ArrayFromHexString("0100", 1).toString(); // the number 256 cannot fit into 1 byte
   }).toThrow("hex value cannot fit in a buffer of 1 byte(s)");
+
+  // TOO SHORT - test a hex string with less bytes than the "length" parameter provided
+  const hexString2 =
+    "5234d08dfa2c815f3097b8ba848a28172e85bec78886e8e201afccb166fc"; // length is 30 bytes, so must be padded with 2 0's at the beginning
+  const expectedUint8Array2 = new Uint8Array([
+    0, 0, 82, 52, 208, 141, 250, 44, 129, 95, 48, 151, 184, 186, 132, 138, 40,
+    23, 46, 133, 190, 199, 136, 134, 232, 226, 1, 175, 204, 177, 102, 252,
+  ]);
+  expect(uint8ArrayFromHexString(hexString2, 32)).toEqual(expectedUint8Array2); // Hex string => Uint8Array
+
+  // TOO LONG - test a hex string with less bytes than the "length" parameter provided -- Should error
+  const hexString3 =
+    "5234d08dfa2c815f3097b8ba848a28172e85bec78886e8e201afccb166fcfafbfcfd"; // length is 34 bytes, so no additional padding will be added
+  expect(() => uint8ArrayFromHexString(hexString3, 32)).toThrow(
+    "hex value cannot fit in a buffer of 32 byte(s)"
+  );
 });
 
 // Test for hexStringToBase64url

packages/sdk-browser/src/__tests__/utils-test.ts

@@ -0,0 +1,14 @@
+import { test, expect } from "@jest/globals";
+import { createEmbeddedAPIKey } from "../utils";
+
+test("createEmbeddedAPIKey", async function () {
+  // Test valid uncompressed public key
+  const uncompPubKey =
+    "0400d2eb47be2006c29db5fe9941dd686d19ddeea85a0328894f08091f6b5be9b366c4872345594c12a7f7c47c62dd8074542934820fce5ee0ddc55d6d1d8dd312";
+  await expect(createEmbeddedAPIKey(uncompPubKey)).resolves.not.toThrow();
+
+  // test invalid uncompressed public key (last byte has been changed)
+  const uncompPubKeyInvalid =
+    "0400d2eb47be2006c29db5fe9941dd686d19ddeea85a0328894f08091f6b5be9b366c4872345594c12a7f7c47c62dd8074542934820fce5ee0ddc55d6d1d8dd311";
+  await expect(createEmbeddedAPIKey(uncompPubKeyInvalid)).rejects.toThrow();
+});

packages/sdk-browser/src/utils.ts

@@ -10,6 +10,7 @@ import bs58check from "bs58check";
 import { AeadId, CipherSuite, KdfId, KemId } from "hpke-js";
 
 import type { EmbeddedAPIKey } from "./models";
+import { pointDecode } from "@turnkey/api-key-stamper";
 
 // createEmbeddedAPIKey creates an embedded API key encrypted to a target key (typically embedded within an iframe).
 // This returns a bundle that can be decrypted by that target key, as well as the public key of the newly created API key.
@@ -30,9 +31,11 @@ export const createEmbeddedAPIKey = async (
 
   // 3: import the targetPublicKey (i.e. passed in from the iframe)
   const targetKeyBytes = uint8ArrayFromHexString(targetPublicKey);
+  const jwk = pointDecode(targetKeyBytes);
+
   const targetKey = await crypto.subtle.importKey(
-    "raw",
-    targetKeyBytes,
+    "jwk",
+    jwk,
     {
       name: "ECDH",
       namedCurve: "P-256",