Add native RSA keygen (WebCrypto) support for Safari/iOS

src/crypto/public_key/rsa.js

@@ -135,7 +135,6 @@ function RSA() {
 
   function generate(B, E) {
     var webCrypto = util.getWebCrypto();
-    var promise;
 
     //
     // Native RSA keygen using Web Crypto
@@ -144,22 +143,41 @@ function RSA() {
     if (webCrypto) {
       var Euint32 = new Uint32Array([parseInt(E, 16)]); // get integer of exponent
       var Euint8 = new Uint8Array(Euint32.buffer); // get bytes of exponent
-      var keyGenOpt = {
-        name: 'RSASSA-PKCS1-v1_5',
-        modulusLength: B, // the specified keysize in bits
-        publicExponent: Euint8.subarray(0, 3), // take three bytes (max 65537)
-        hash: {
-          name: 'SHA-1' // not required for actual RSA keys, but for crypto api 'sign' and 'verify'
-        }
-      };
-      promise = webCrypto.generateKey(keyGenOpt, true, ['sign', 'verify']);
-      return promise.then(exportKey).then(decodeKey);
+      var keyGenOpt;
+
+      if (window.crypto.subtle) {
+        // current standard spec
+        keyGenOpt = {
+          name: 'RSASSA-PKCS1-v1_5',
+          modulusLength: B, // the specified keysize in bits
+          publicExponent: Euint8.subarray(0, 3), // take three bytes (max 65537)
+          hash: {
+            name: 'SHA-1' // not required for actual RSA keys, but for crypto api 'sign' and 'verify'
+          }
+        };
+        return webCrypto.generateKey(keyGenOpt, true, ['sign', 'verify']).then(exportKey).then(decodeKey);
+
+      } else if (window.crypto.webkitSubtle) {
+        // outdated spec implemented by Webkit
+        keyGenOpt = {
+          name: 'RSA-OAEP',
+          modulusLength: B, // the specified keysize in bits
+          publicExponent: Euint8.subarray(0, 3), // take three bytes (max 65537)
+        };
+        return webCrypto.generateKey(keyGenOpt, true, ['encrypt', 'decrypt']).then(exportKey).then(function(key) {
+          if (key instanceof ArrayBuffer) {
+            // parse raw ArrayBuffer bytes to jwk/json (WebKit/Safari quirk)
+            return decodeKey(JSON.parse(String.fromCharCode.apply(null, new Uint8Array(key))));
+          }
+          return decodeKey(key);
+        });
+      }
     }
 
-    function exportKey(key) {
+    function exportKey(keypair) {
       // export the generated keys as JsonWebKey (JWK)
       // https://tools.ietf.org/html/draft-ietf-jose-json-web-key-33
-      return webCrypto.exportKey('jwk', key.privateKey);
+      return webCrypto.exportKey('jwk', keypair.privateKey);
     }
 
     function decodeKey(jwk) {
@@ -185,7 +203,7 @@ function RSA() {
     // JS code
     //
 
-    promise = new Promise(function(resolve) {
+    return new Promise(function(resolve) {
       var key = new keyObject();
       var rng = new SecureRandom();
       var qs = B >> 1;
@@ -223,8 +241,6 @@ function RSA() {
 
       resolve(key);
     });
-
-    return promise;
   }
 
   this.encrypt = encrypt;

src/util.js

@@ -320,8 +320,8 @@ module.exports = {
       return;
     }
 
-    if (typeof window !== 'undefined' && window.crypto && window.crypto.subtle) {
-      return window.crypto.subtle;
+    if (typeof window !== 'undefined' && window.crypto) {
+      return window.crypto.subtle || window.crypto.webkitSubtle;
     }
   }
 };