Update: Use WebCrypto API for PBKDF2 (#92)

cisco · Mar 3, 2017 · 5e5b9d3 · 5e5b9d3
1 parent c327c04
commit 5e5b9d3
Showing 1 changed file with 106 additions and 4 deletions.
diff --git a/lib/algorithms/pbes2.js b/lib/algorithms/pbes2.js
@@ -70,8 +70,63 @@ function pbes2EncryptFN(hmac, kw) {
     return promise;
   };
 
-  // NOTE: WebCrypto API missing until there's better support
-  var webcrypto = null;
+  var webcrypto = function(key, pdata, props) {
+    var salt = util.asBuffer(props.p2s || new Buffer(0), "base64url"),
+        itrs = props.p2c || 0;
+
+    if (0 >= itrs) {
+      return Promise.reject(new Error("invalid iteration count"));
+    }
+    if (8 > salt.length) {
+      return Promise.reject(new Error("salt too small"));
+    }
+    salt = fixSalt(hmac, kw, salt);
+
+    var promise;
+
+    // STEP 1: derive shared key
+    var hash = hmac.replace("HS", "SHA-");
+    promise = Promise.resolve(key);
+    promise = promise.then(function(keyval) {
+      return helpers.subtleCrypto.importKey("raw", keyval, "PBKDF2", false, ["deriveKey"]);
+    });
+    promise = promise.then(function(key) {
+      var mainAlgo = {
+        name: "PBKDF2",
+        salt: salt,
+        iterations: itrs,
+        hash: hash
+      };
+      var deriveAlgo = {
+        name: "AES-KW",
+        length: keyLen * 8
+      };
+
+      return helpers.subtleCrypto.deriveKey(mainAlgo, key, deriveAlgo, true, ["wrapKey", "unwrapKey"]);
+    });
+    // STEP 2: encrypt cek
+    promise = promise.then(function(dk) {
+      // assume subtleCrypto for keywrap
+      return Promise.all([
+        helpers.subtleCrypto.importKey("raw", pdata, { name: "HMAC", hash: "SHA-256" }, true, ["sign"]),
+        dk
+      ]);
+    });
+    promise = promise.then(function(keys) {
+      return helpers.subtleCrypto.wrapKey("raw",
+                                          keys[0], // key
+                                          keys[1], // wrappingKey
+                                          "AES-KW");
+    });
+    promise = promise.then(function(result) {
+      result = new Buffer(result);
+
+      return {
+        data: result
+      };
+    });
+    return promise;
+  };
 
   var nodejs = function(key, pdata, props) {
     if (6 > helpers.nodeCrypto.pbkdf2.length) {
@@ -165,8 +220,55 @@ function pbes2DecryptFN(hmac, kw) {
     return promise;
   };
 
-  // NOTE: WebCrypto API missing until there's better support
-  var webcrypto = null;
+  var webcrypto = function(key, cdata, props) {
+    props = props || {};
+
+    var salt = util.asBuffer(props.p2s || new Buffer(0), "base64url"),
+        itrs = props.p2c || 0;
+
+    if (0 >= itrs) {
+      return Promise.reject(new Error("invalid iteration count"));
+    }
+
+    if (8 > salt.length) {
+      return Promise.reject(new Error("salt too small"));
+    }
+    salt = fixSalt(hmac, kw, salt);
+
+    var hash = hmac.replace("HS", "SHA-");
+    var promise;
+    promise = Promise.resolve(key);
+    promise = promise.then(function(keyval) {
+      return helpers.subtleCrypto.importKey("raw", keyval, "PBKDF2", false, ["deriveKey"]);
+    });
+    promise = promise.then(function(key) {
+      var mainAlgo = {
+        name: "PBKDF2",
+        salt: salt,
+        iterations: itrs,
+        hash: hash
+      };
+      var deriveAlgo = {
+        name: "AES-KW",
+        length: keyLen * 8
+      };
+
+      return helpers.subtleCrypto.deriveKey(mainAlgo, key, deriveAlgo, true, ["wrapKey", "unwrapKey"]);
+    });
+    // STEP 2: decrypt cek
+    promise = promise.then(function(key) {
+      return helpers.subtleCrypto.unwrapKey("raw", cdata, key, "AES-KW", {name: "HMAC", hash: "SHA-256"}, true, ["sign"]);
+    });
+    promise = promise.then(function(result) {
+      // unwrapped CryptoKey -- extract raw
+      return helpers.subtleCrypto.exportKey("raw", result);
+    });
+    promise = promise.then(function(result) {
+      result = new Buffer(result);
+      return result;
+    });
+    return promise;
+  };
 
   var nodejs = function(key, cdata, props) {
     if (6 > helpers.nodeCrypto.pbkdf2.length) {