Fix: avoid using obsolete AesGcm (#4165)

Co-authored-by: Christopher Schuchardt <[email protected]>

Author: Wi1l-B0t

src/Neo/Cryptography/Helper.cs

@@ -32,6 +32,9 @@ public static class Helper
     {
         private static readonly bool s_isOSX = RuntimeInformation.IsOSPlatform(OSPlatform.OSX);
 
+        private const int AesNonceSizeBytes = 12;
+        private const int AesTagSizeBytes = 16;
+
         /// <summary>
         /// Computes the hash value for the specified byte array using the ripemd160 algorithm.
         /// </summary>
@@ -229,22 +232,22 @@ public static byte[] Keccak256(this Span<byte> value)
 
         public static byte[] AES256Encrypt(this byte[] plainData, byte[] key, byte[] nonce, byte[] associatedData = null)
         {
-            if (nonce.Length != 12) throw new ArgumentOutOfRangeException(nameof(nonce), "`nonce` must be 12 bytes");
-            var tag = new byte[16];
+            if (nonce.Length != AesNonceSizeBytes)
+                throw new ArgumentOutOfRangeException(nameof(nonce), $"`nonce` must be {AesNonceSizeBytes} bytes");
+
+            var tag = new byte[AesTagSizeBytes];
             var cipherBytes = new byte[plainData.Length];
             if (!s_isOSX)
             {
-#pragma warning disable SYSLIB0053 // Type or member is obsolete
-                using var cipher = new AesGcm(key);
-#pragma warning restore SYSLIB0053 // Type or member is obsolete
+                using var cipher = new AesGcm(key, AesTagSizeBytes);
                 cipher.Encrypt(nonce, plainData, cipherBytes, tag, associatedData);
             }
             else
             {
                 var cipher = new GcmBlockCipher(new AesEngine());
                 var parameters = new AeadParameters(
                     new KeyParameter(key),
-                    128, //128 = 16 * 8 => (tag size * 8)
+                    AesTagSizeBytes * 8, // 128 = 16 * 8 => (tag size * 8)
                     nonce,
                     associatedData);
                 cipher.Init(true, parameters);
@@ -257,24 +260,25 @@ public static byte[] AES256Encrypt(this byte[] plainData, byte[] key, byte[] non
 
         public static byte[] AES256Decrypt(this byte[] encryptedData, byte[] key, byte[] associatedData = null)
         {
+            if (encryptedData.Length < AesNonceSizeBytes + AesTagSizeBytes)
+                throw new ArgumentException($"The encryptedData.Length must be greater than {AesNonceSizeBytes} + {AesTagSizeBytes}");
+
             ReadOnlySpan<byte> encrypted = encryptedData;
-            var nonce = encrypted[..12];
-            var cipherBytes = encrypted[12..^16];
-            var tag = encrypted[^16..];
+            var nonce = encrypted[..AesNonceSizeBytes];
+            var cipherBytes = encrypted[AesNonceSizeBytes..^AesTagSizeBytes];
+            var tag = encrypted[^AesTagSizeBytes..];
             var decryptedData = new byte[cipherBytes.Length];
             if (!s_isOSX)
             {
-#pragma warning disable SYSLIB0053 // Type or member is obsolete
-                using var cipher = new AesGcm(key);
-#pragma warning restore SYSLIB0053 // Type or member is obsolete
+                using var cipher = new AesGcm(key, AesTagSizeBytes);
                 cipher.Decrypt(nonce, cipherBytes, tag, decryptedData, associatedData);
             }
             else
             {
                 var cipher = new GcmBlockCipher(new AesEngine());
                 var parameters = new AeadParameters(
                     new KeyParameter(key),
-                    128,  //128 = 16 * 8 => (tag size * 8)
+                    AesTagSizeBytes * 8,  // 128 = 16 * 8 => (tag size * 8)
                     nonce.ToArray(),
                     associatedData);
                 cipher.Init(false, parameters);

tests/Neo.UnitTests/Cryptography/UT_Cryptography_Helper.cs

@@ -30,18 +30,17 @@ public class UT_Cryptography_Helper
         public void TestBase58CheckDecode()
         {
             string input = "3vQB7B6MrGQZaxCuFg4oh";
-            byte[] result = input.Base58CheckDecode();
+            var result = input.Base58CheckDecode();
             byte[] helloWorld = { 104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100 };
             CollectionAssert.AreEqual(helloWorld, result);
 
             input = "3v";
-            Action action = () => input.Base58CheckDecode();
+            var action = () => input.Base58CheckDecode();
             Assert.ThrowsExactly<FormatException>(action);
 
             input = "3vQB7B6MrGQZaxCuFg4og";
             action = () => input.Base58CheckDecode();
             Assert.ThrowsExactly<FormatException>(action);
-
             Assert.ThrowsExactly<FormatException>(() => _ = string.Empty.Base58CheckDecode());
         }
 
@@ -90,20 +89,22 @@ public void TestKeccak256()
         public void TestRIPEMD160()
         {
             ReadOnlySpan<byte> value = Encoding.ASCII.GetBytes("hello world");
-            byte[] result = value.RIPEMD160();
+            var result = value.RIPEMD160();
             Assert.AreEqual("98c615784ccb5fe5936fbc0cbe9dfdb408d92f0f", result.ToHexString());
         }
 
         [TestMethod]
         public void TestAESEncryptAndDecrypt()
         {
-            NEP6Wallet wallet = new NEP6Wallet("", "1", TestProtocolSettings.Default);
+            var wallet = new NEP6Wallet("", "1", TestProtocolSettings.Default);
             wallet.CreateAccount();
-            WalletAccount account = wallet.GetAccounts().ToArray()[0];
-            KeyPair key = account.GetKey();
-            Random random = new Random();
-            byte[] nonce = new byte[12];
+
+            var account = wallet.GetAccounts().ToArray()[0];
+            var key = account.GetKey();
+            var random = new Random();
+            var nonce = new byte[12];
             random.NextBytes(nonce);
+
             var cypher = Helper.AES256Encrypt(Encoding.UTF8.GetBytes("hello world"), key.PrivateKey, nonce);
             var m = Helper.AES256Decrypt(cypher, key.PrivateKey);
             var message2 = Encoding.UTF8.GetString(m);
@@ -113,35 +114,41 @@ public void TestAESEncryptAndDecrypt()
         [TestMethod]
         public void TestEcdhEncryptAndDecrypt()
         {
-            NEP6Wallet wallet = new NEP6Wallet("", "1", ProtocolSettings.Default);
+            var wallet = new NEP6Wallet("", "1", ProtocolSettings.Default);
             wallet.CreateAccount();
             wallet.CreateAccount();
-            WalletAccount account1 = wallet.GetAccounts().ToArray()[0];
-            KeyPair key1 = account1.GetKey();
-            WalletAccount account2 = wallet.GetAccounts().ToArray()[1];
-            KeyPair key2 = account2.GetKey();
+
+            var account1 = wallet.GetAccounts().ToArray()[0];
+            var key1 = account1.GetKey();
+            var account2 = wallet.GetAccounts().ToArray()[1];
+            var key2 = account2.GetKey();
             Console.WriteLine($"Account:{1},privatekey:{key1.PrivateKey.ToHexString()},publicKey:{key1.PublicKey.ToArray().ToHexString()}");
             Console.WriteLine($"Account:{2},privatekey:{key2.PrivateKey.ToHexString()},publicKey:{key2.PublicKey.ToArray().ToHexString()}");
+
             var secret1 = Helper.ECDHDeriveKey(key1, key2.PublicKey);
             var secret2 = Helper.ECDHDeriveKey(key2, key1.PublicKey);
             Assert.AreEqual(secret1.ToHexString(), secret2.ToHexString());
+
             var message = Encoding.ASCII.GetBytes("hello world");
-            Random random = new Random();
-            byte[] nonce = new byte[12];
+            var random = new Random();
+            var nonce = new byte[12];
             random.NextBytes(nonce);
+
             var cypher = message.AES256Encrypt(secret1, nonce);
             cypher.AES256Decrypt(secret2);
             Assert.AreEqual("hello world", Encoding.ASCII.GetString(cypher.AES256Decrypt(secret2)));
+
+            Assert.ThrowsExactly<ArgumentException>(() => Helper.AES256Decrypt(new byte[11], key1.PrivateKey));
+            Assert.ThrowsExactly<ArgumentException>(() => Helper.AES256Decrypt(new byte[11 + 16], key1.PrivateKey));
         }
 
         [TestMethod]
         public void TestTest()
         {
             int m = 7, n = 10;
             uint nTweak = 123456;
-            BloomFilter filter = new(m, n, nTweak);
-
-            Transaction tx = new()
+            var filter = new BloomFilter(m, n, nTweak);
+            var tx = new Transaction()
             {
                 Script = TestUtils.GetByteArray(32, 0x42),
                 SystemFee = 4200000000,