Update signature authentication (#89)

* Add nonce to payload

* Upgrade to Hashing to SHA-384

* Resolve * to single class imports

* Satisfy linter on testcase docstring => added those checks to local environment also.

Author: cdr-chakotay

Diff for: src/main/java/com/transloadit/sdk/Request.java

@@ -14,7 +14,9 @@
 import org.joda.time.format.DateTimeFormatter;
 import org.json.JSONObject;
 
+import javax.crypto.KeyGenerator;
 import javax.crypto.Mac;
+import javax.crypto.SecretKey;
 import javax.crypto.spec.SecretKeySpec;
 import java.io.File;
 import java.io.IOException;
@@ -26,6 +28,7 @@
 import java.security.InvalidKeyException;
 import java.security.NoSuchAlgorithmException;
 import java.util.ArrayList;
+import java.util.Base64;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Random;
@@ -303,6 +306,7 @@ private RequestBody getBody(Map<String, String> data, @Nullable Map<String, File
     private Map<String, String> toPayload(Map<String, Object> data) throws LocalOperationException {
         Map<String, Object> dataClone = new HashMap<String, Object>(data);
         dataClone.put("auth", getAuthData());
+        dataClone.put("nonce", getNonce("AES", 256));
 
         Map<String, String> payload = new HashMap<String, String>();
         payload.put("params", jsonifyData(dataClone));
@@ -350,14 +354,14 @@ private Map<String, String> getAuthData() {
      */
     private String getSignature(String message) throws LocalOperationException {
         byte[] kSecret = transloadit.secret.getBytes(Charset.forName("UTF-8"));
-        byte[] rawHmac = hmacSHA1(kSecret, message);
+        byte[] rawHmac = hmacSHA384(kSecret, message);
         byte[] hexBytes = new Hex().encode(rawHmac);
-
-        return new String(hexBytes, Charset.forName("UTF-8"));
+        String signature = "sha384:" + new String(hexBytes, Charset.forName("UTF-8"));
+        return signature;
     }
 
-    private byte[] hmacSHA1(byte[] key, String data) throws LocalOperationException {
-        final String algorithm = "HmacSHA1";
+    private byte[] hmacSHA384(byte[] key, String data) throws LocalOperationException {
+        final String algorithm = "HmacSHA384";
         Mac mac;
 
         try {
@@ -371,6 +375,25 @@ private byte[] hmacSHA1(byte[] key, String data) throws LocalOperationException
         return mac.doFinal(data.getBytes(Charset.forName("UTF-8")));
     }
 
+    /**
+     * Generates a strong cryptographic nonce in order to make the request's signature unique.
+     * @param cipher Algorithm to derive key with
+     * @param lengthInBits Length of the generated key in bits
+     * @return A Key formatted as String
+     */
+    protected String getNonce(String cipher, int lengthInBits) {
+        KeyGenerator keyGenerator = null;
+        try {
+            keyGenerator = KeyGenerator.getInstance(cipher);
+        } catch (NoSuchAlgorithmException e) {
+            throw new RuntimeException(e);
+        }
+        keyGenerator.init(lengthInBits);
+         SecretKey secKey = keyGenerator.generateKey();
+         String encodedKey = Base64.getEncoder().encodeToString(secKey.getEncoded());
+        return encodedKey;
+    }
+
     /**
      * Helper method, which performs a retryRateLimit action if a POST request has hit the servers rate limit.
      * All parameters of the failed POST request should be provided to this method.

Diff for: src/test/java/com/transloadit/sdk/RequestTest.java

@@ -179,6 +179,18 @@ public void retryAfterSpecificErrors() throws LocalOperationException, RequestEx
         testRequest.delete("/foo", new HashMap<String, Object>());
     }
 
+    /**
+     * Test secure nonce generation with.
+     */
+    @Test
+    public void getNonce() {
+        String cipher = "Blowfish";
+        int keyLength = 256;
+
+        String nonce = request.getNonce(cipher, keyLength);
+        assertEquals(44, nonce.length());
+    }
+
     /**
      * Tests if {@link Request#delayBeforeRetry()} works.
      * @throws LocalOperationException
@@ -194,8 +206,4 @@ public void delayBeforeRetry() throws LocalOperationException {
         assertTrue(delta >= timeout);
 
     }
-
-
-
 }
-