/// <summary>
/// Factory method for creating instances of the string encryptor classes.
/// </summary>
/// <param name="alg">Type of encryption algorithm.</param>
/// <returns>IStringEncryptor interface representing the chosen string encryptor.</returns>
public static IStringEncryptor GetStringEncryptor(pfEncryptionAlgorithm alg)
{
IStringEncryptor enc;
switch (alg)
{
case pfEncryptionAlgorithm.AES:
enc = new StringEncryptorAES();
break;
case pfEncryptionAlgorithm.DES:
enc = new StringEncryptorDES();
break;
case pfEncryptionAlgorithm.TripleDES:
enc = new StringEncryptorTripleDES();
break;
default:
enc = new StringEncryptorAES();
break;
}
return(enc);
}
/// <summary>
/// Loads contents of encryptedInputFile to string, decrypts the string and returns decrypted string to caller.
/// </summary>
/// <param name="encryptedInputFile">Path to file containing encrypted data.</param>
/// <returns>Decrypted string.</returns>
public string Decrypt(string encryptedInputFile)
{
string encryptedString = string.Empty;
string decryptedString = string.Empty;
IStringEncryptor encryptor = new StringEncryptorAES();
if (String.IsNullOrEmpty(encryptedInputFile))
{
throw new ArgumentNullException("Path to both the encrypted input file needs to be specified.");
}
if (KeyIsValid(GetStringFromByteArray(_key)) == false)
{
throw new System.Exception("Invalid length for Key.");
}
if (IVIsValid(GetStringFromByteArray(_iv)) == false)
{
throw new System.Exception("Invalid length for IV.");
}
try
{
encryptedString = File.ReadAllText(encryptedInputFile);
encryptor.Key = this.Key;
encryptor.IV = this.IV;
decryptedString = encryptor.Decrypt(encryptedString);
}
catch (System.Exception ex)
{
_msg.Length = 0;
_msg.Append("Attempt to decrypt file to string failed: Make sure you are using the same key and IV used to encryp ");
_msg.Append(encryptedInputFile);
_msg.Append("\r\n");
_msg.Append("Error Message:");
_msg.Append("\r\n");
_msg.Append(AppMessages.FormatErrorMessage(ex));
throw new System.Exception(_msg.ToString());
}
finally
{
;
}
return(decryptedString);
}
/// <summary>
/// Decrypts by loading encryptedInputFile to a string and then decrypting the string. Decrypted string is then written out as text to the outputFile.
/// </summary>
/// <param name="encryptedInputFile">Full path to file containing the encrypted data.</param>
/// <param name="outputFile">Full path to file that will contain decrypted data.</param>
/// <returns>Returns path to output file.</returns>
public string Decrypt(string encryptedInputFile, string outputFile)
{
IStringEncryptor encryptor = new StringEncryptorAES();
if (String.IsNullOrEmpty(encryptedInputFile) || String.IsNullOrEmpty(outputFile))
{
throw new ArgumentNullException("Paths to both the encrypted input file and the output file need to be specified.");
}
if (KeyIsValid(GetStringFromByteArray(_key)) == false)
{
throw new System.Exception("Invalid length for Key.");
}
if (IVIsValid(GetStringFromByteArray(_iv)) == false)
{
throw new System.Exception("Invalid length for IV.");
}
try
{
string encryptedData = File.ReadAllText(encryptedInputFile);
encryptor.Key = this.Key;
encryptor.IV = this.IV;
string decryptedData = encryptor.Decrypt(encryptedData);
File.WriteAllText(outputFile, decryptedData);
}
catch (System.Exception ex)
{
_msg.Length = 0;
_msg.Append("Attempt to decrypt file ");
_msg.Append(encryptedInputFile);
_msg.Append(" failed. Verify you are using same key/iv pair used to encrypt. Error message: ");
_msg.Append("\r\n");
_msg.Append(AppMessages.FormatErrorMessage(ex));
throw new System.Exception(_msg.ToString());
}
finally
{
;
}
return(outputFile);
}
/// <summary>
/// Encrypts by loading inputFile to a string and then encrypting the string. String is then written out as text to the encryptedOutputFile.
/// </summary>
/// <param name="inputFile">Full path to file that will be encrypted.</param>
/// <param name="encryptedOutputFile">Full path to file that will contain encrypted data.</param>
/// <returns>Returns path to encrypted output file.</returns>
public string Encrypt(string inputFile, string encryptedOutputFile)
{
IStringEncryptor encryptor = new StringEncryptorAES();
if (String.IsNullOrEmpty(inputFile) || String.IsNullOrEmpty(encryptedOutputFile))
{
throw new ArgumentNullException("Paths to both input and encrypted output file need to specified.");
}
if (KeyIsValid(GetStringFromByteArray(_key)) == false)
{
throw new System.Exception("Invalid length for Key.");
}
if (IVIsValid(GetStringFromByteArray(_iv)) == false)
{
throw new System.Exception("Invalid length for IV.");
}
try
{
string data = File.ReadAllText(inputFile);
encryptor.Key = this.Key;
encryptor.IV = this.IV;
string encryptedData = encryptor.Encrypt(data);
File.WriteAllText(encryptedOutputFile, encryptedData);
}
catch (System.Exception ex)
{
_msg.Length = 0;
_msg.Append("Attempt to encrypt file ");
_msg.Append(inputFile);
_msg.Append(" failed with following message: ");
_msg.Append("\r\n");
_msg.Append(AppMessages.FormatErrorMessage(ex));
throw new System.Exception(_msg.ToString());
}
finally
{
;
}
return(encryptedOutputFile);
}
