fix breaking change in 4.0.1 branch (still support smaller iv sizes)

Author: MauriceButler

index.js

@@ -32,9 +32,27 @@ function Cryptr(secret) {
         const stringValue = String(value);
         const iv = Buffer.from(stringValue.slice(0, 32), 'hex');
         const encrypted = stringValue.slice(32);
+        let legacyValue = false;
+        let decipher;
+
+        try {
+            decipher = crypto.createDecipheriv(algorithm, key, iv);
+        } catch (exception) {
+            if (exception.message === 'Invalid IV length') {
+                legacyValue = true;
+            } else {
+                throw exception;
+            }
+        }
+
+        if (!legacyValue) {
+            return decipher.update(encrypted, 'hex', 'utf8') + decipher.final('utf8');
+        }
 
-        const decipher = crypto.createDecipheriv(algorithm, key, iv);
-        return decipher.update(encrypted, 'hex', 'utf8') + decipher.final('utf8');
+        const legacyIv = stringValue.slice(0, 16);
+        const legacyEncrypted = stringValue.slice(16);
+        decipher = crypto.createDecipheriv(algorithm, key, legacyIv);
+        return decipher.update(legacyEncrypted, 'hex', 'utf8') + decipher.final('utf8');
     };
 }
 

tests/index.js

@@ -11,7 +11,17 @@ test('works...', t => {
     const encryptedString = cryptr.encrypt(testData);
     const decryptedString = cryptr.decrypt(encryptedString);
 
-    t.equal(decryptedString, testData, 'decrypted aes256 correctly');
+    t.equal(decryptedString, testData, 'decrypted sha256 correctly');
+});
+
+test('works with old iv size values', t => {
+    t.plan(1);
+
+    const cryptr = new Cryptr(testSecret);
+
+    const decryptedString = cryptr.decrypt('5590fd6409be2494de0226f5d7');
+
+    t.equal(decryptedString, 'bacon', 'decrypted old iv value');
 });
 
 test('goes bang if bad secret', t => {