From 75c60b71e20986e04aada7ff5b5f8f12f1a730d2 Mon Sep 17 00:00:00 2001
From: Matt Nadareski <mnadareski@outlook.com>
Date: Tue, 12 May 2026 20:42:49 -0400
Subject: [PATCH] Port AES/CBC code from Serialization

---
 SabreTools.Security.Cryptography/AESCBC.cs | 88 ++++++++++++++++++++++
 SabreTools.Security.Cryptography/AESCTR.cs |  4 +-
 2 files changed, 90 insertions(+), 2 deletions(-)
 create mode 100644 SabreTools.Security.Cryptography/AESCBC.cs

diff --git a/SabreTools.Security.Cryptography/AESCBC.cs b/SabreTools.Security.Cryptography/AESCBC.cs
new file mode 100644
index 0000000..f740bba
--- /dev/null
+++ b/SabreTools.Security.Cryptography/AESCBC.cs
@@ -0,0 +1,88 @@
+using System;
+using Org.BouncyCastle.Crypto;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Security;
+
+namespace SabreTools.Security.Cryptography
+{
+    public static class AESCBC
+    {
+        /// <summary>
+        /// Create AES/CBC with no padding decryption cipher and intialize
+        /// </summary>
+        /// <param name="key">Byte array representation of 128-bit encryption key</param>
+        /// <param name="iv">AES initial value for counter</param>
+        /// <returns>Initialized AES cipher</returns>
+        /// <exception cref="ArgumentOutOfRangeException">
+        /// Thrown if <paramref name="key"/> does not have a length of 16.
+        /// </exception>
+        public static IBufferedCipher CreateDecryptionCipher(byte[] key, byte[] iv)
+        {
+            if (key.Length != 16)
+                throw new ArgumentOutOfRangeException(nameof(key));
+
+            var keyParam = new KeyParameter(key);
+            var cipher = CipherUtilities.GetCipher("AES/CBC/NoPadding");
+            cipher.Init(forEncryption: false, new ParametersWithIV(keyParam, iv));
+            return cipher;
+        }
+
+        /// <summary>
+        /// Create AES/CBC with no padding encryption cipher and intialize
+        /// </summary>
+        /// <param name="key">Byte array representation of 128-bit encryption key</param>
+        /// <param name="iv">AES initial value for counter</param>
+        /// <returns>Initialized AES cipher</returns>
+        /// <exception cref="ArgumentOutOfRangeException">
+        /// Thrown if <paramref name="key"/> does not have a length of 16.
+        /// </exception>
+        public static IBufferedCipher CreateEncryptionCipher(byte[] key, byte[] iv)
+        {
+            if (key.Length != 16)
+                throw new ArgumentOutOfRangeException(nameof(key));
+
+            var keyParam = new KeyParameter(key);
+            var cipher = CipherUtilities.GetCipher("AES/CBC/NoPadding");
+            cipher.Init(forEncryption: true, new ParametersWithIV(keyParam, iv));
+            return cipher;
+        }
+
+        /// <summary>
+        /// Decrypts <paramref name="data"/> with AES-128-CBC (no padding).
+        /// Returns null if any argument is invalid or decryption fails.
+        /// </summary>
+        /// <param name="data">Ciphertext to decrypt.</param>
+        /// <param name="key">16-byte AES key.</param>
+        /// <param name="iv">16-byte initialisation vector.</param>
+        public static byte[]? Decrypt(byte[] data, byte[] key, byte[] iv)
+        {
+            // Validate the key and IV
+            if (key.Length != 16)
+                return null;
+            if (iv.Length != 16)
+                return null;
+
+            var cipher = CreateDecryptionCipher(key, iv);
+            return cipher.DoFinal(data);
+        }
+
+        /// <summary>
+        /// Encrypts <paramref name="data"/> with AES-128-CBC (no padding).
+        /// Returns null if any argument is invalid or encryption fails.
+        /// </summary>
+        /// <param name="data">Plaintext to encrypt.</param>
+        /// <param name="key">16-byte AES key.</param>
+        /// <param name="iv">16-byte initialisation vector.</param>
+        public static byte[]? Encrypt(byte[] data, byte[] key, byte[] iv)
+        {
+            // Validate the key and IV
+            if (key.Length != 16)
+                return null;
+            if (iv.Length != 16)
+                return null;
+
+            var cipher = CreateEncryptionCipher(key, iv);
+            return cipher.DoFinal(data);
+        }
+    }
+}
diff --git a/SabreTools.Security.Cryptography/AESCTR.cs b/SabreTools.Security.Cryptography/AESCTR.cs
index a09fd69..bd7322e 100644
--- a/SabreTools.Security.Cryptography/AESCTR.cs
+++ b/SabreTools.Security.Cryptography/AESCTR.cs
@@ -11,7 +11,7 @@ namespace SabreTools.Security.Cryptography
     public static class AESCTR
     {
         /// <summary>
-        /// Create AES decryption cipher and intialize
+        /// Create AES/CTR decryption cipher and intialize
         /// </summary>
         /// <param name="key">Byte array representation of 128-bit encryption key</param>
         /// <param name="iv">AES initial value for counter</param>
@@ -31,7 +31,7 @@ namespace SabreTools.Security.Cryptography
         }
 
         /// <summary>
-        /// Create AES encryption cipher and intialize
+        /// Create AES/CTR encryption cipher and intialize
         /// </summary>
         /// <param name="key">Byte array representation of 128-bit encryption key</param>
         /// <param name="iv">AES initial value for counter</param>