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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;
}
}
}
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