wasSharpNET – Blame information for rev 1

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1 office 1 ///////////////////////////////////////////////////////////////////////////
2 // Copyright (C) Wizardry and Steamworks 2016 - License: GNU GPLv3 //
3 // Please see: http://www.gnu.org/licenses/gpl.html for legal details, //
4 // rights of fair usage, the disclaimer and warranty conditions. //
5 ///////////////////////////////////////////////////////////////////////////
6  
7 using System;
8 using System.Collections.Generic;
9 using System.IO;
10 using System.Linq;
11 using System.Security.Cryptography;
12 using System.Text;
13  
14 namespace wasSharpNET.Cryptography
15 {
16 public class AES
17 {
18 private static readonly RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
19 private const int AES_BLOCK_SIZE = 128;
20 private const CipherMode AES_CIPHER_MODE = CipherMode.CBC;
21 private const PaddingMode AES_PADDING_MODE = PaddingMode.PKCS7;
22 private const int AES_KEY_SALT_BYTES = 16;
23  
24 ///////////////////////////////////////////////////////////////////////////
25 // Copyright (C) Wizardry and Steamworks 2016 - License: GNU GPLv3 //
26 ///////////////////////////////////////////////////////////////////////////
27 /// <summary>
28 /// Encrypts a string given a key and initialization vector.
29 /// </summary>
30 /// <param name="data">the string to encrypt</param>
31 /// <param name="key">the encryption key</param>
32 /// <param name="separator">the separator to use between the cyphertext and the IV</param>
33 /// <returns>Base64 encoded encrypted data</returns>
34 public string wasAESEncrypt(string data, string key, string separator = ":")
35 {
36 using (var rijdanelManaged = new RijndaelManaged())
37 {
38 // FIPS-197 / CBC
39 rijdanelManaged.BlockSize = AES_BLOCK_SIZE;
40 rijdanelManaged.Mode = AES_CIPHER_MODE;
41 rijdanelManaged.Padding = AES_PADDING_MODE;
42  
43 // Compute the salt and the IV from the key.
44 var salt = new byte[AES_KEY_SALT_BYTES];
45 rng.GetBytes(salt);
46 var derivedKey = new Rfc2898DeriveBytes(key, salt);
47 rijdanelManaged.Key = derivedKey.GetBytes(rijdanelManaged.KeySize/8);
48 rijdanelManaged.IV = derivedKey.GetBytes(rijdanelManaged.BlockSize/8);
49  
50 byte[] encryptedData;
51 using (var encryptor = rijdanelManaged.CreateEncryptor(rijdanelManaged.Key, rijdanelManaged.IV))
52 {
53 using (var memoryStream = new MemoryStream())
54 {
55 using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
56 {
57 using (var streamWriter = new StreamWriter(cryptoStream))
58 {
59 streamWriter.Write(data);
60 }
61 }
62 encryptedData = memoryStream.ToArray();
63 }
64 }
65 return string.Join(separator, Convert.ToBase64String(salt), Convert.ToBase64String(encryptedData));
66 }
67 }
68  
69 ///////////////////////////////////////////////////////////////////////////
70 // Copyright (C) Wizardry and Steamworks 2016 - License: GNU GPLv3 //
71 ///////////////////////////////////////////////////////////////////////////
72 /// <summary>
73 /// Decrypts a Base64 encoded string using AES with a given key and initialization vector.
74 /// </summary>
75 /// <param name="data">
76 /// a string consisting of the cyphertext to decrypt in Base64 and the IV in Base64 separated by the
77 /// separator
78 /// </param>
79 /// <param name="key">the encryption key</param>
80 /// <param name="separator">the separator to use between the cyphertext and the IV</param>
81 /// <returns>the decrypted data</returns>
82 public string wasAESDecrypt(string data, string key, string separator = ":")
83 {
84 // retrieve the salt from the data.
85 var segments = new List<string>(data.Split(new[] {separator}, StringSplitOptions.None));
86 if (!segments.Count.Equals(2))
87 throw new ArgumentException("Invalid data.");
88  
89 string plaintext;
90 using (var rijdanelManaged = new RijndaelManaged())
91 {
92 // FIPS-197 / CBC
93 rijdanelManaged.BlockSize = AES_BLOCK_SIZE;
94 rijdanelManaged.Mode = AES_CIPHER_MODE;
95 rijdanelManaged.Padding = AES_PADDING_MODE;
96  
97 // Retrieve the key and the IV from the salt.
98 var derivedKey = new Rfc2898DeriveBytes(key, Convert.FromBase64String(segments.First().Trim()));
99 rijdanelManaged.Key = derivedKey.GetBytes(rijdanelManaged.KeySize/8);
100 rijdanelManaged.IV = derivedKey.GetBytes(rijdanelManaged.BlockSize/8);
101  
102 using (var decryptor = rijdanelManaged.CreateDecryptor(rijdanelManaged.Key, rijdanelManaged.IV))
103 {
104 using (var memoryStream = new MemoryStream(Convert.FromBase64String(segments.Last().Trim())))
105 {
106 using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
107 {
108 using (var streamReader = new StreamReader(cryptoStream))
109 {
110 plaintext = streamReader.ReadToEnd();
111 }
112 }
113 }
114 }
115 }
116 return plaintext;
117 }
118 }
119 }