かけがえのない愛

// Initialize internal values

this._Key = new byte[24];

this._IV = new byte[16]; 


// Perform a hash operation using the phrase.  This will generate

// a unique 48 character value to be used as the key and IV.

byte[] bytePhrase = Encoding.ASCII.GetBytes(Phrase);

SHA384Managed sha384 = new SHA384Managed();

sha384.ComputeHash(bytePhrase);

byte[] result = sha384.Hash;

 

// Transfer the first 24 characters of the hashed value to the key

// and 16 more characters for the initialization vector.

for( int loop=0; loop<24; loop++ ) this._Key[loop] = result[loop];

for( int loop=24; loop<40; loop++ ) this._IV[loop-24] = result[loop];

using System;

using System.IO;

using System.Security.Cryptography;

using System.Text;


internal class MyEncryptor

{

  // Internal value of the phrase used to generate the secret key

  private string _Phrase = "";

  /// Set the phrase used to generate the secret key.

  public override string Phrase

  {

    set 

    { 

       this._Phrase = value; 

       this.GenerateKey();

    }

  }


  // Internal initialization vector value to 

  // encrypt/decrypt the first block

  private byte[] _IV;


  // Internal secret key value

  private byte[] _Key;


    /// 


  /// Constructor

  /// 


  /// Secret phrase to 

       generate key

    public MyEncryptor(string SecretPhrase)

  {

     this.Phrase = SecretPhrase;

  }


  /// 


  /// Encrypt the given value with the Rijndael algorithm.

  /// 


  /// Value to encrypt

  /// Encrypted value. 

  public string Encrypt(string EncryptValue)

  {

    CryptoStream encryptStream = null;       // Stream used to encrypt

    RijndaelManaged rijndael = null;         // Rijndael provider

    ICryptoTransform rijndaelEncrypt = null; // Encrypting object

    MemoryStream memStream = new MemoryStream(); // Stream to contain 

                                                 // data


    try

    {

      if( EncryptValue.Length > 0 )

      {

        // Create the crypto objects

        rijndael = new RijndaelManaged();

        rijndael.Key = this._Key;

        rijndael.IV = this._IV;

        rijndaelEncrypt = rijndael.CreateEncryptor();

        encryptStream = new CryptoStream(

             memStream, rijndaelEncrypt, CryptoStreamMode.Write);


        // Write the encrypted value into memory

        byte[] input = Encoding.UTF8.GetBytes(EncryptValue);

        encryptStream.Write(input, 0, input.Length);

        encryptStream.FlushFinalBlock();


        // Retrieve the encrypted value and return it

        return( Convert.ToBase64String(memStream.ToArray()) );

      }

      else

      {

        return "";

      }

    }

    finally

    {

      if( rijndael != null ) rijndael.Clear();

      if( rijndaelEncrypt != null ) rijndaelEncrypt.Dispose();

      if( memStream != null ) memStream.Close();

    }

  }


  /*****************************************************************

   * Generate an encryption key based on the given phrase.  The 

   * phrase is hashed to create a unique 32 character (256-bit) 

   * value, of which 24 characters (192 bit) are used for the

   * key and the remaining 8 are used for the initialization 

   * vector (IV).

   * 

   * Parameters:  SecretPhrase - phrase to generate the key and 

   * IV from.

   * 

   * Return Val:  None  

   ***************************************************************/

  private void GenerateKey(string SecretPhrase)

  {

    // Initialize internal values

    this._Key = new byte[24];

    this._IV = new byte[16]; 


    // Perform a hash operation using the phrase.  This will 

    // generate a unique 32 character value to be used as the key.

    byte[] bytePhrase = Encoding.ASCII.GetBytes(SecretPhrase);

    SHA384Managed sha384 = new SHA384Managed();

    sha384.ComputeHash(bytePhrase);

    byte[] result = sha384.Hash;

 

    // Transfer the first 24 characters of the hashed value to the key

    // and the remaining 8 characters to the intialization vector.

    for( int loop=0; loop<24; loop++ ) this._Key[loop] = result[loop];

    for( int loop=24; loop<40; loop++ ) this._IV[loop-24] = result[loop];

  }

}