first commit

2026-03-11 11:18:25 -05:00
commit f3cb730f3b
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+using System.Security.Cryptography;
+using System.Text;
+
+namespace Landmark.OLA.Application.Common.Security
+{
+    public static class CookieCryptor
+    {
+        private static byte[] RandomBytes(int len)
+        {
+            var b = new byte[len];
+            RandomNumberGenerator.Fill(b);
+            return b;
+        }
+
+        private static byte[] DeriveKey(string pass, byte[] salt, int keyBytes = 32, int iterations = 100_000)
+            => new Rfc2898DeriveBytes(pass, salt, iterations, HashAlgorithmName.SHA256).GetBytes(keyBytes);
+
+
+        public static string EncryptJwt(string jwt, string key)
+        {
+            var salt = RandomBytes(32);
+
+            using var aes = Aes.Create();
+            aes.KeySize = 256;
+            aes.BlockSize = 128;
+            aes.Mode = CipherMode.CBC;
+            aes.Padding = PaddingMode.PKCS7;
+
+            aes.GenerateIV();
+            aes.Key = DeriveKey(key, salt, 32);
+
+            using var ms = new MemoryStream();
+
+            ms.Write(salt, 0, salt.Length);
+            ms.Write(aes.IV, 0, aes.IV.Length);
+
+            using (var crypto = new CryptoStream(ms, aes.CreateEncryptor(), CryptoStreamMode.Write))
+            using (var writer = new StreamWriter(crypto, Encoding.UTF8))
+            {
+                writer.Write(jwt);
+                writer.Flush();
+                crypto.FlushFinalBlock();
+            }
+
+            return Convert.ToBase64String(ms.ToArray());
+        }
+
+        public static string DecryptJwt(string cipherText, string passPhrase)
+        {
+            var all = Convert.FromBase64String(cipherText);
+
+            var saltLen = 32;
+            var ivLen = 16;
+
+            if (all.Length < saltLen + ivLen)
+                throw new CryptographicException("Ciphertext too short.");
+
+            var salt = new byte[saltLen];
+            Buffer.BlockCopy(all, 0, salt, 0, saltLen);
+
+            var iv = new byte[ivLen];
+            Buffer.BlockCopy(all, saltLen, iv, 0, ivLen);
+
+            var cipher = new byte[all.Length - saltLen - ivLen];
+            Buffer.BlockCopy(all, saltLen + ivLen, cipher, 0, cipher.Length);
+
+            using var aes = Aes.Create();
+            aes.KeySize = 256;
+            aes.BlockSize = 128;
+            aes.Mode = CipherMode.CBC;
+            aes.Padding = PaddingMode.PKCS7;
+            aes.Key = DeriveKey(passPhrase, salt, 32);
+            aes.IV = iv;
+
+            using var ms = new MemoryStream(cipher);
+            using var crypto = new CryptoStream(ms, aes.CreateDecryptor(), CryptoStreamMode.Read);
+            using var reader = new StreamReader(crypto, Encoding.UTF8);
+
+            return reader.ReadToEnd();
+        }
+    }
+}