From e6ca7a484d9cc213fb00c34ebf7cb55ace892c04 Mon Sep 17 00:00:00 2001
From: ivarlovlie <git@ivarlovlie.no>
Date: Wed, 31 Mar 2021 18:00:22 +0200
Subject: Initial commit

---
 src/IOL.VippsEcommerce/Helpers.cs | 86 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 src/IOL.VippsEcommerce/Helpers.cs

(limited to 'src/IOL.VippsEcommerce/Helpers.cs')

diff --git a/src/IOL.VippsEcommerce/Helpers.cs b/src/IOL.VippsEcommerce/Helpers.cs
new file mode 100644
index 0000000..8d6fb50
--- /dev/null
+++ b/src/IOL.VippsEcommerce/Helpers.cs
@@ -0,0 +1,86 @@
+using System;
+using System.IO;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace IOL.VippsEcommerce
+{
+	internal static class Helpers
+	{
+		private const int AES_BLOCK_BYTE_SIZE = 128 / 8;
+		private static readonly RandomNumberGenerator _random = RandomNumberGenerator.Create();
+
+		public static bool IsNullOrWhiteSpace(this string value) => string.IsNullOrWhiteSpace(value);
+		public static bool IsPresent(this string value) => !string.IsNullOrWhiteSpace(value);
+
+		public static bool IsDirectoryWritable(this string dirPath, bool throwIfFails = false) {
+			try {
+				using (var fs = File.Create(
+				                            Path.Combine(dirPath, Path.GetRandomFileName()),
+				                            1,
+				                            FileOptions.DeleteOnClose)
+				) { }
+
+				return true;
+			} catch {
+				if (throwIfFails)
+					throw;
+
+				return false;
+			}
+		}
+
+		//https://tomrucki.com/posts/aes-encryption-in-csharp/
+		public static string EncryptWithAes(this string toEncrypt, string password) {
+			var key = GetKey(password);
+
+			using var aes = CreateAes();
+			var iv = GenerateRandomBytes(AES_BLOCK_BYTE_SIZE);
+			var plainText = Encoding.UTF8.GetBytes(toEncrypt);
+
+			using var encryptor = aes.CreateEncryptor(key, iv);
+			var cipherText = encryptor
+				.TransformFinalBlock(plainText, 0, plainText.Length);
+
+			var result = new byte[iv.Length + cipherText.Length];
+			iv.CopyTo(result, 0);
+			cipherText.CopyTo(result, iv.Length);
+
+			return Convert.ToBase64String(result);
+		}
+
+		private static Aes CreateAes() {
+			var aes = Aes.Create();
+			aes.Mode = CipherMode.CBC;
+			aes.Padding = PaddingMode.PKCS7;
+			return aes;
+		}
+
+		public static string DecryptWithAes(this string input, string password) {
+			var key = GetKey(password);
+			var encryptedData = Convert.FromBase64String(input);
+
+			using var aes = CreateAes();
+			var iv = encryptedData.Take(AES_BLOCK_BYTE_SIZE).ToArray();
+			var cipherText = encryptedData.Skip(AES_BLOCK_BYTE_SIZE).ToArray();
+
+			using var decryptor = aes.CreateDecryptor(key, iv);
+			var decryptedBytes = decryptor
+				.TransformFinalBlock(cipherText, 0, cipherText.Length);
+			return Encoding.UTF8.GetString(decryptedBytes);
+		}
+
+		private static byte[] GetKey(string password) {
+			var keyBytes = Encoding.UTF8.GetBytes(password);
+			using var md5 = MD5.Create();
+			return md5.ComputeHash(keyBytes);
+		}
+
+		private static byte[] GenerateRandomBytes(int numberOfBytes) {
+			var randomBytes = new byte[numberOfBytes];
+			_random.GetBytes(randomBytes);
+			return randomBytes;
+		}
+	}
+}
\ No newline at end of file
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