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AES Two-way salting encryption

I use the following class, written by Mark Brittingham, for two-way AES encryption in my application. How can I change it to add a solo line?

using System; using System.Data; using System.Security.Cryptography; using System.IO; public class SimpleAES { // Change these keys private byte[] Key = { 123, 217, 19, 11, 24, 26, 85, 45, 114, 184, 27, 162, 37, 112, 222, 209, 241, 24, 175, 144, 173, 53, 196, 29, 24, 26, 17, 218, 131, 236, 53, 209 }; private byte[] Vector = { 146, 64, 191, 111, 23, 3, 113, 119, 231, 121, 2521, 112, 79, 32, 114, 156 }; private ICryptoTransform EncryptorTransform, DecryptorTransform; private System.Text.UTF8Encoding UTFEncoder; public SimpleAES() { //This is our encryption method RijndaelManaged rm = new RijndaelManaged(); //Create an encryptor and a decryptor using our encryption method, key, and vector. EncryptorTransform = rm.CreateEncryptor(this.Key, this.Vector); DecryptorTransform = rm.CreateDecryptor(this.Key, this.Vector); //Used to translate bytes to text and vice versa UTFEncoder = new System.Text.UTF8Encoding(); } /// -------------- Two Utility Methods (not used but may be useful) ----------- /// Generates an encryption key. static public byte[] GenerateEncryptionKey() { //Generate a Key. RijndaelManaged rm = new RijndaelManaged(); rm.GenerateKey(); return rm.Key; } /// Generates a unique encryption vector static public byte[] GenerateEncryptionVector() { //Generate a Vector RijndaelManaged rm = new RijndaelManaged(); rm.GenerateIV(); return rm.IV; } /// ----------- The commonly used methods ------------------------------ /// Encrypt some text and return a string suitable for passing in a URL. public string EncryptToString(string TextValue) { return ByteArrToString(Encrypt(TextValue)); } /// Encrypt some text and return an encrypted byte array. public byte[] Encrypt(string TextValue) { //Translates our text value into a byte array. Byte[] bytes = UTFEncoder.GetBytes(TextValue); //Used to stream the data in and out of the CryptoStream. MemoryStream memoryStream = new MemoryStream(); /* * We will have to write the unencrypted bytes to the stream, * then read the encrypted result back from the stream. */ #region Write the decrypted value to the encryption stream CryptoStream cs = new CryptoStream(memoryStream, EncryptorTransform, CryptoStreamMode.Write); cs.Write(bytes, 0, bytes.Length); cs.FlushFinalBlock(); #endregion #region Read encrypted value back out of the stream memoryStream.Position = 0; byte[] encrypted = new byte[memoryStream.Length]; memoryStream.Read(encrypted, 0, encrypted.Length); #endregion //Clean up. cs.Close(); memoryStream.Close(); return encrypted; } /// The other side: Decryption methods public string DecryptString(string EncryptedString) { return Decrypt(StrToByteArray(EncryptedString)); } /// Decryption when working with byte arrays. public string Decrypt(byte[] EncryptedValue) { #region Write the encrypted value to the decryption stream MemoryStream encryptedStream = new MemoryStream(); CryptoStream decryptStream = new CryptoStream(encryptedStream, DecryptorTransform, CryptoStreamMode.Write); decryptStream.Write(EncryptedValue, 0, EncryptedValue.Length); decryptStream.FlushFinalBlock(); #endregion #region Read the decrypted value from the stream. encryptedStream.Position = 0; Byte[] decryptedBytes = new Byte[encryptedStream.Length]; encryptedStream.Read(decryptedBytes, 0, decryptedBytes.Length); encryptedStream.Close(); #endregion return UTFEncoder.GetString(decryptedBytes); } /// Convert a string to a byte array. NOTE: Normally we'd create a Byte Array from a string using an ASCII encoding (like so). // System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding(); // return encoding.GetBytes(str); // However, this results in character values that cannot be passed in a URL. So, instead, I just // lay out all of the byte values in a long string of numbers (three per - must pad numbers less than 100). public byte[] StrToByteArray(string str) { if (str.Length == 0) throw new Exception("Invalid string value in StrToByteArray"); byte val; byte[] byteArr = new byte[str.Length / 3]; int i = 0; int j = 0; do { val = byte.Parse(str.Substring(i, 3)); byteArr[j++] = val; i += 3; } while (i < str.Length); return byteArr; } // Same comment as above. Normally the conversion would use an ASCII encoding in the other direction: // System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding(); // return enc.GetString(byteArr); public string ByteArrToString(byte[] byteArr) { byte val; string tempStr = ""; for (int i = 0; i <= byteArr.GetUpperBound(0); i++) { val = byteArr[i]; if (val < (byte)10) tempStr += "00" + val.ToString(); else if (val < (byte)100) tempStr += "0" + val.ToString(); else tempStr += val.ToString(); } return tempStr; } }
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2 answers

I used a solo line with hashed passwords, but not with two-way encryption. So, take this offer with grain ...

Add a salt string along with your key and vector (they really should be stored elsewhere, not hardcoded in your class, but for now this will work).

 private string salt = " $e7?8f@l4 ";

Use it in EncryptToString added to the text value:

 return ByteArrToString(Encrypt(TextValue + salt));

Then delete it in DecryptString:

 return Decrypt(StrToByteArray(EncryptedString)).Replace(salt, string.Empty);
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I recently discovered Mark code and modified it a bit. I added some salt by adding crypto numbers to the beginning and end of the byte array. The salt size can be changed using constant salt. Thus, the same text almost never looks the same when encrypted. However, since it is two-way encrypted, if someone sees your code, he knows your key, your vector, and where is the salt ...

 using System; using System.Security.Cryptography; using System.IO; public class SimpleAES { // Change these keys private byte[] Key = { 123, 217, 19, 11, 24, 26, 85, 45, 114, 184, 27, 162, 37, 112, 222, 209, 241, 24, 175, 144, 173, 53, 196, 29, 24, 26, 17, 218, 131, 236, 53, 209 }; private byte[] Vector = { 146, 64, 191, 111, 23, 3, 113, 119, 231, 121, 2521, 112, 79, 32, 114, 156 }; private const int Salt = 8; private ICryptoTransform EncryptorTransform, DecryptorTransform; private System.Text.UTF8Encoding UTFEncoder; public SimpleAES() { //This is our encryption method RijndaelManaged rm = new RijndaelManaged(); //Create an encryptor and a decryptor using our encryption method, key, and vector. EncryptorTransform = rm.CreateEncryptor(this.Key, this.Vector); DecryptorTransform = rm.CreateDecryptor(this.Key, this.Vector); //Used to translate bytes to text and vice versa UTFEncoder = new System.Text.UTF8Encoding(); } /// -------------- Two Utility Methods (not used but may be useful) ----------- /// Generates an encryption key. static public byte[] GenerateEncryptionKey() { //Generate a Key. RijndaelManaged rm = new RijndaelManaged(); rm.GenerateKey(); return rm.Key; } /// Generates a unique encryption vector static public byte[] GenerateEncryptionVector() { //Generate a Vector RijndaelManaged rm = new RijndaelManaged(); rm.GenerateIV(); return rm.IV; } /// ----------- The commonly used methods ------------------------------ /// Encrypt some text and return a string suitable for passing in a URL. public string EncryptString(string TextValue) { return (TextValue != "") ? Convert.ToBase64String(Encrypt(TextValue)) : ""; } /// Encrypt some text and return an encrypted byte array. public byte[] Encrypt(string TextValue) { //Translates our text value into a byte array. Byte[] pepper = UTFEncoder.GetBytes(TextValue); // add salt Byte[] salt = new byte[Salt]; RNGCryptoServiceProvider crypto = new RNGCryptoServiceProvider(); crypto.GetNonZeroBytes(salt); Byte[] bytes = new byte[2 * Salt + pepper.Length]; System.Buffer.BlockCopy(salt, 0, bytes, 0, Salt); System.Buffer.BlockCopy(pepper, 0, bytes, Salt, pepper.Length); crypto.GetNonZeroBytes(salt); System.Buffer.BlockCopy(salt, 0, bytes, Salt + pepper.Length, Salt); //Used to stream the data in and out of the CryptoStream. MemoryStream memoryStream = new MemoryStream(); /* * We will have to write the unencrypted bytes to the stream, * then read the encrypted result back from the stream. */ #region Write the decrypted value to the encryption stream CryptoStream cs = new CryptoStream(memoryStream, EncryptorTransform, CryptoStreamMode.Write); cs.Write(bytes, 0, bytes.Length); cs.FlushFinalBlock(); #endregion #region Read encrypted value back out of the stream memoryStream.Position = 0; byte[] encrypted = new byte[memoryStream.Length]; memoryStream.Read(encrypted, 0, encrypted.Length); #endregion //Clean up. cs.Close(); memoryStream.Close(); return encrypted; } /// The other side: Decryption methods public string DecryptString(string EncryptedString) { return (EncryptedString != "") ? Decrypt(Convert.FromBase64String(EncryptedString)) : ""; } /// Decryption when working with byte arrays. public string Decrypt(byte[] EncryptedValue) { #region Write the encrypted value to the decryption stream MemoryStream encryptedStream = new MemoryStream(); CryptoStream decryptStream = new CryptoStream(encryptedStream, DecryptorTransform, CryptoStreamMode.Write); decryptStream.Write(EncryptedValue, 0, EncryptedValue.Length); decryptStream.FlushFinalBlock(); #endregion #region Read the decrypted value from the stream. encryptedStream.Position = 0; Byte[] decryptedBytes = new Byte[encryptedStream.Length]; encryptedStream.Read(decryptedBytes, 0, decryptedBytes.Length); encryptedStream.Close(); #endregion // remove salt int len = decryptedBytes.Length - 2 * Salt; Byte[] pepper = new Byte[len]; System.Buffer.BlockCopy(decryptedBytes, Salt, pepper, 0, len); return UTFEncoder.GetString(pepper); } }
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Source: https://habr.com/ru/post/1304181/

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