From 5ee211017912bc0837cbce3b845e6ab4a7887885 Mon Sep 17 00:00:00 2001
From: Divy Srivastava <dj.srivastava23@gmail.com>
Date: Sun, 29 Aug 2021 17:53:51 +0530
Subject: [PATCH] feat(ext/crypto): support JWK export for HMAC (#11864)

---
 cli/tests/unit/webcrypto_test.ts | 11 +++++--
 ext/crypto/00_crypto.js          | 49 ++++++++++++++++++++++++++++++--
 ext/crypto/lib.deno_crypto.d.ts  |  8 ++++--
 3 files changed, 61 insertions(+), 7 deletions(-)

diff --git a/cli/tests/unit/webcrypto_test.ts b/cli/tests/unit/webcrypto_test.ts
index a37e32eba1..475efde6c0 100644
--- a/cli/tests/unit/webcrypto_test.ts
+++ b/cli/tests/unit/webcrypto_test.ts
@@ -254,6 +254,8 @@ const jwk: JsonWebKey = {
   // unpadded base64 for rawKey.
   k: "AQIDBAUGBwgJCgsMDQ4PEA",
   alg: "HS256",
+  ext: true,
+  "key_ops": ["sign"],
 };
 
 unitTest(async function subtleCryptoHmacImportExport() {
@@ -297,7 +299,10 @@ unitTest(async function subtleCryptoHmacImportExport() {
     new Uint8Array(actual2),
     expected,
   );
-  // TODO(@littledivy): Add a test for exporting JWK key when supported.
-  const exportedKey = await crypto.subtle.exportKey("raw", key1);
-  assertEquals(new Uint8Array(exportedKey), rawKey);
+
+  const exportedKey1 = await crypto.subtle.exportKey("raw", key1);
+  assertEquals(new Uint8Array(exportedKey1), rawKey);
+
+  const exportedKey2 = await crypto.subtle.exportKey("jwk", key2);
+  assertEquals(exportedKey2, jwk);
 });
diff --git a/ext/crypto/00_crypto.js b/ext/crypto/00_crypto.js
index 375170ad9c..ab6347d41b 100644
--- a/ext/crypto/00_crypto.js
+++ b/ext/crypto/00_crypto.js
@@ -12,7 +12,7 @@
   const core = window.Deno.core;
   const webidl = window.__bootstrap.webidl;
   const { DOMException } = window.__bootstrap.domException;
-  const { atob } = window.__bootstrap.base64;
+  const { atob, btoa } = window.__bootstrap.base64;
 
   const {
     ArrayPrototypeFind,
@@ -122,6 +122,13 @@
     return keyBytes;
   }
 
+  function unpaddedBase64(bytes) {
+    const binaryString = core.decode(bytes);
+    const base64String = btoa(binaryString);
+
+    return StringPrototypeReplace(base64String, /=/g, "");
+  }
+
   // See https://www.w3.org/TR/WebCryptoAPI/#dfn-normalize-an-algorithm
   // 18.4.4
   function normalizeAlgorithm(algorithm, op) {
@@ -970,10 +977,48 @@
               // 4-5.
               return bits.buffer;
             }
-            // TODO(@littledivy): jwk
+            case "jwk": {
+              // 1-3.
+              const jwk = {
+                kty: "oct",
+                k: unpaddedBase64(innerKey.data),
+              };
+              // 4.
+              const algorithm = key[_algorithm];
+              // 5.
+              const hash = algorithm.hash;
+              // 6.
+              switch (hash.name) {
+                case "SHA-1":
+                  jwk.alg = "HS1";
+                  break;
+                case "SHA-256":
+                  jwk.alg = "HS256";
+                  break;
+                case "SHA-384":
+                  jwk.alg = "HS384";
+                  break;
+                case "SHA-512":
+                  jwk.alg = "HS512";
+                  break;
+                default:
+                  throw new DOMException(
+                    "Hash algorithm not supported",
+                    "NotSupportedError",
+                  );
+              }
+              // 7.
+              jwk.key_ops = key.usages;
+              // 8.
+              jwk.ext = key[_extractable];
+              // 9.
+              return jwk;
+            }
             default:
               throw new DOMException("Not implemented", "NotSupportedError");
           }
+          // TODO(@littledivy): Redundant break but deno_lint complains without it
+          break;
         }
         // TODO(@littledivy): RSASSA-PKCS1-v1_5
         // TODO(@littledivy): RSA-PSS
diff --git a/ext/crypto/lib.deno_crypto.d.ts b/ext/crypto/lib.deno_crypto.d.ts
index 2e8d2f8b2b..5169e5c3bd 100644
--- a/ext/crypto/lib.deno_crypto.d.ts
+++ b/ext/crypto/lib.deno_crypto.d.ts
@@ -25,7 +25,7 @@ type KeyUsage =
   | "unwrapKey"
   | "verify"
   | "wrapKey";
-
+type KeyFormat = "jwk" | "pkcs8" | "raw" | "spki";
 type NamedCurve = string;
 
 interface RsaOtherPrimesInfo {
@@ -164,7 +164,11 @@ interface SubtleCrypto {
     extractable: boolean,
     keyUsages: KeyUsage[],
   ): Promise<CryptoKey>;
-  exportKey(format: "raw", key: CryptoKey): Promise<ArrayBuffer>;
+  exportKey(format: "jwk", key: CryptoKey): Promise<JsonWebKey>;
+  exportKey(
+    format: Exclude<KeyFormat, "jwk">,
+    key: CryptoKey,
+  ): Promise<ArrayBuffer>;
   sign(
     algorithm: AlgorithmIdentifier | RsaPssParams | EcdsaParams,
     key: CryptoKey,