/// <summary>
/// Decrypts WAV file with SDS.
/// </summary>
/// <param name="EncryptedWAVFile">WAV file to decrypt</param>
/// <param name="DecryptedWAVFile">Decrypted WAV file</param>
/// <param name="key">Decryption key - seed value for random number generator (same value should have been used for encryption)</param>
public static void DecryptWAVFile(WAVFile EncryptedWAVFile, WAVFile DecryptedWAVFile, int key)
{
// SDS values x1[i], x1[i+1], x1[i+2], c3 (contains encrypted sample value)
double x1i, x1i1, x1i2, c3;
// Normally distributed random variable z and white noise value n
double z, n;
// Decrypted sample value
short sample;
// Seed a new random (seed value is our key)
Random rnd = new Random(key);
using (FileStream fsEncrypted = new FileStream(EncryptedWAVFile.FileName, FileMode.Open, FileAccess.Read))
using (BinaryReader br = new BinaryReader(fsEncrypted))
using (FileStream fsDecrypted = new FileStream(DecryptedWAVFile.FileName, FileMode.Append, FileAccess.Write))
using (BinaryWriter bw = new BinaryWriter(fsDecrypted))
{
// Move to data position right after the header (header size is 44 bytes)
br.BaseStream.Position = 44;
int samplesCount = 0;
while (br.BaseStream.Length > br.BaseStream.Position)
{
// We need to read 3 consecutive SDS values x1[i], x1[i+1] and x1[i+2]
x1i = br.ReadDouble();
// We could reach EOF after reading
if (!(br.BaseStream.Length > br.BaseStream.Position))
break;
x1i1 = br.ReadDouble();
// We could reach EOF after reading
if (!(br.BaseStream.Length > br.BaseStream.Position))
break;
x1i2 = br.ReadDouble();
// Move 2 double positions back because we have read 3 values instead of 1
br.BaseStream.Seek(-2 * sizeof(double), SeekOrigin.Current);
// Calculate white noise value
z = Z1 + Z2 * rnd.NextDouble();
n = z * Math.Sqrt(N0 / DT);
// Calculate decrypted c3 parameter value
c3 = GetC3Decrypted(x1i, x1i1, x1i2, n);
// TODO: Several decrypted c3s are false. Should throw an exception as sample will be out of 'short' range
/*
//sample = Convert.ToInt16(c3);
if ((samplesCount == 48598) || (samplesCount == 48600))
{
//System.Diagnostics.Debugger.Break();
Console.WriteLine("Count {0}: {1}", samplesCount, c3);
}
if ((c3 > 1.0f) || (c3 < -1.0f))
{
//System.Diagnostics.Debugger.Break();
Console.WriteLine("{0} - {1}", c3, samplesCount);
}
*/
// Denormalize c3 value from [-1; 1] range to [-32768; 32767]
if (c3 < 0)
{
c3 *= Modif;
}
else
{
c3 *= Modif - 1;
}
// Convert to 16-bit sample (rounding is important when converting from floating point!)
sample = (short)Math.Round(c3);
// Decrypted sample is written to file
bw.Write(sample);
samplesCount++;
}
Console.WriteLine("Finished decrypting {0} samples.", samplesCount);
}
}
/// <summary>
/// Encrypts WAV file with SDS.
/// </summary>
/// <param name="OriginalWAVFile">WAV file to encrypt</param>
/// <param name="EncryptedWAVFile">Encrypted WAV file</param>
/// <param name="key">Encryption key - seed value for random number generator (same value should be used for decryption)</param>
public static void EncryptWAVFile(WAVFile OriginalWAVFile, WAVFile EncryptedWAVFile, int key)
{
// SDS values and white noise
double x1, x2, n;
// SDS values from previous step, required for calculations
double x1Prev, x2Prev, nPrev;
// Normally distributed random variable z and SDS input parameter c3 - normalized sample
double z, c3;
// Sound sample from WAV file
short sample;
// Seed a new random (seed value is our key)
Random rnd = new Random(key);
// Filling starting values
z = Z1 + Z2 * rnd.NextDouble();
nPrev = z * Math.Sqrt(N0 / DT);
x1Prev = X10;
x2Prev = X20;
using (FileStream fsOriginal = new FileStream(OriginalWAVFile.FileName, FileMode.Open, FileAccess.Read))
using (BinaryReader br = new BinaryReader(fsOriginal))
using (FileStream fsEncrypted = new FileStream(EncryptedWAVFile.FileName, FileMode.Append, FileAccess.Write))
using (BinaryWriter bw = new BinaryWriter(fsEncrypted))
{
// Move to data position right after the header (header size is 44 bytes)
br.BaseStream.Position = 44;
// x1 starting value is written as the first sample into encrypted file
bw.Write(x1Prev);
int samplesCount = 0;
while (br.BaseStream.Length > br.BaseStream.Position)
{
// Read 16-bit sample from WAV file
sample = br.ReadInt16();
// Normalize sample to [-1; 1]
if (sample < 0)
{
c3 = ((double)sample) / Modif;
}
else
{
c3 = ((double)sample) / (Modif - 1);
}
// TODO: Bug in decryption
/*
if ((samplesCount == 48598) || (samplesCount == 48600))
{
//System.Diagnostics.Debugger.Break();
Console.WriteLine("Count {0}: {1}", samplesCount, c3);
}
if ((samplesCount == 48599) || (samplesCount == 50954) || (samplesCount == 76648) || (samplesCount == 98925) || (samplesCount == 123705))
{
//System.Diagnostics.Debugger.Break();
Console.WriteLine("{0} - {1}", c3, samplesCount);
}
*/
// Calculate white noise and SDS values
z = Z1 + Z2 * rnd.NextDouble();
n = z * Math.Sqrt(N0 / DT);
x1 = GetX1Encrypted(x1Prev, x2Prev);
x2 = GetX2Encrypted(c3, x1Prev, x2Prev, nPrev);
// x1 is the encrypted sample so it's written to file
bw.Write(x1);
samplesCount++;
// Set current values as previous for the next iteration
x1Prev = x1;
x2Prev = x2;
nPrev = n;
}
Console.WriteLine("Finished encrypting {0} samples.", samplesCount);
}
}
static void Main(string[] args)
{
if (args.Length == 1)
{
string fileNameOriginal = args[0];
if (fileNameOriginal.Contains(".wav"))
{
// Set encrypted file name to "%fileNameOriginal% (encrypted).wav"
string fileNameEncrypted = fileNameOriginal.Insert(fileNameOriginal.IndexOf(".wav"), " (encrypted)");
// Set decrypted file name to "%fileNameOriginal% (decrypted).wav"
string fileNameDecrypted = fileNameOriginal.Insert(fileNameOriginal.IndexOf(".wav"), " (decrypted)");
//
// Input
//
WAVFile WAVFileOriginal = new WAVFile(fileNameOriginal);
// Read WAV file header
WAVFileOriginal.ReadWAVHeader();
// Output basic WAV file info
WAVFileOriginal.GetWAVFileInfo();
//
// Encryption
//
WAVFile WAVFileEncrypted = new WAVFile(fileNameEncrypted);
// Copy original WAV file header
WAVFileEncrypted.Header = WAVFileOriginal.Header;
// Fix WAV header for encrypted file and write it
WAVFileEncrypted.CreateEncryptedWAVFile();
// Encrypt WAV file with SDS and seed value 1
SDS.EncryptWAVFile(WAVFileOriginal, WAVFileEncrypted, 1);
//
// Decryption
//
WAVFile WAVFileDecrypted = new WAVFile(fileNameDecrypted);
// Copy original WAV file header
WAVFileDecrypted.Header = WAVFileOriginal.Header;
// Fix WAV header for decrypted file and write it
WAVFileDecrypted.CreateDecryptedWAVFile();
// Decrypt WAV file with SDS and seed value 1
SDS.DecryptWAVFile(WAVFileEncrypted, WAVFileDecrypted, 1);
}
else
{
Console.WriteLine("Please supply a correct WAV file for encryption.");
}
}
else
{
Console.WriteLine("Please supply only a WAV file for encryption.");
}
}
/// <summary>
/// Encrypts WAV file with SDS.
/// </summary>
/// <param name="OriginalWAVFile">WAV file to encrypt</param>
/// <param name="EncryptedWAVFile">Encrypted WAV file</param>
/// <param name="key">Encryption key - seed value for random number generator (same value should be used for decryption)</param>
public static void EncryptWAVFile(WAVFile OriginalWAVFile, WAVFile EncryptedWAVFile, int key)
{
// SDS values and white noise
double x1, x2, n;
// SDS values from previous step, required for calculations
double x1Prev, x2Prev, nPrev;
// Normally distributed random variable z and SDS input parameter c3 - normalized sample
double z, c3;
// Sound sample from WAV file
short sample;
// Seed a new random (seed value is our key)
Random rnd = new Random(key);
// Filling starting values
z = Z1 + Z2 * rnd.NextDouble();
nPrev = z * Math.Sqrt(N0 / DT);
x1Prev = X10;
x2Prev = X20;
using (FileStream fsOriginal = new FileStream(OriginalWAVFile.FileName, FileMode.Open, FileAccess.Read))
using (BinaryReader br = new BinaryReader(fsOriginal))
using (FileStream fsEncrypted = new FileStream(EncryptedWAVFile.FileName, FileMode.Append, FileAccess.Write))
using (BinaryWriter bw = new BinaryWriter(fsEncrypted))
{
// Move to data position right after the header (header size is 44 bytes)
br.BaseStream.Position = 44;
// x1 starting value is written as the first sample into encrypted file
bw.Write(x1Prev);
int samplesCount = 0;
while (br.BaseStream.Length > br.BaseStream.Position)
{
// Read 16-bit sample from WAV file
sample = br.ReadInt16();
// Normalize sample to [-1; 1]
if (sample < 0)
{
c3 = ((double)sample) / Modif;
}
else
{
c3 = ((double)sample) / (Modif - 1);
}
// TODO: Bug in decryption
/*
* if ((samplesCount == 48598) || (samplesCount == 48600))
* {
* //System.Diagnostics.Debugger.Break();
* Console.WriteLine("Count {0}: {1}", samplesCount, c3);
* }
*
* if ((samplesCount == 48599) || (samplesCount == 50954) || (samplesCount == 76648) || (samplesCount == 98925) || (samplesCount == 123705))
* {
* //System.Diagnostics.Debugger.Break();
* Console.WriteLine("{0} - {1}", c3, samplesCount);
* }
*/
// Calculate white noise and SDS values
z = Z1 + Z2 * rnd.NextDouble();
n = z * Math.Sqrt(N0 / DT);
x1 = GetX1Encrypted(x1Prev, x2Prev);
x2 = GetX2Encrypted(c3, x1Prev, x2Prev, nPrev);
// x1 is the encrypted sample so it's written to file
bw.Write(x1);
samplesCount++;
// Set current values as previous for the next iteration
x1Prev = x1;
x2Prev = x2;
nPrev = n;
}
Console.WriteLine("Finished encrypting {0} samples.", samplesCount);
}
}
/// <summary>
/// Decrypts WAV file with SDS.
/// </summary>
/// <param name="EncryptedWAVFile">WAV file to decrypt</param>
/// <param name="DecryptedWAVFile">Decrypted WAV file</param>
/// <param name="key">Decryption key - seed value for random number generator (same value should have been used for encryption)</param>
public static void DecryptWAVFile(WAVFile EncryptedWAVFile, WAVFile DecryptedWAVFile, int key)
{
// SDS values x1[i], x1[i+1], x1[i+2], c3 (contains encrypted sample value)
double x1i, x1i1, x1i2, c3;
// Normally distributed random variable z and white noise value n
double z, n;
// Decrypted sample value
short sample;
// Seed a new random (seed value is our key)
Random rnd = new Random(key);
using (FileStream fsEncrypted = new FileStream(EncryptedWAVFile.FileName, FileMode.Open, FileAccess.Read))
using (BinaryReader br = new BinaryReader(fsEncrypted))
using (FileStream fsDecrypted = new FileStream(DecryptedWAVFile.FileName, FileMode.Append, FileAccess.Write))
using (BinaryWriter bw = new BinaryWriter(fsDecrypted))
{
// Move to data position right after the header (header size is 44 bytes)
br.BaseStream.Position = 44;
int samplesCount = 0;
while (br.BaseStream.Length > br.BaseStream.Position)
{
// We need to read 3 consecutive SDS values x1[i], x1[i+1] and x1[i+2]
x1i = br.ReadDouble();
// We could reach EOF after reading
if (!(br.BaseStream.Length > br.BaseStream.Position))
{
break;
}
x1i1 = br.ReadDouble();
// We could reach EOF after reading
if (!(br.BaseStream.Length > br.BaseStream.Position))
{
break;
}
x1i2 = br.ReadDouble();
// Move 2 double positions back because we have read 3 values instead of 1
br.BaseStream.Seek(-2 * sizeof(double), SeekOrigin.Current);
// Calculate white noise value
z = Z1 + Z2 * rnd.NextDouble();
n = z * Math.Sqrt(N0 / DT);
// Calculate decrypted c3 parameter value
c3 = GetC3Decrypted(x1i, x1i1, x1i2, n);
// TODO: Several decrypted c3s are false. Should throw an exception as sample will be out of 'short' range
/*
* //sample = Convert.ToInt16(c3);
*
* if ((samplesCount == 48598) || (samplesCount == 48600))
* {
* //System.Diagnostics.Debugger.Break();
* Console.WriteLine("Count {0}: {1}", samplesCount, c3);
* }
*
* if ((c3 > 1.0f) || (c3 < -1.0f))
* {
* //System.Diagnostics.Debugger.Break();
* Console.WriteLine("{0} - {1}", c3, samplesCount);
* }
*/
// Denormalize c3 value from [-1; 1] range to [-32768; 32767]
if (c3 < 0)
{
c3 *= Modif;
}
else
{
c3 *= Modif - 1;
}
// Convert to 16-bit sample (rounding is important when converting from floating point!)
sample = (short)Math.Round(c3);
// Decrypted sample is written to file
bw.Write(sample);
samplesCount++;
}
Console.WriteLine("Finished decrypting {0} samples.", samplesCount);
}
}
static void Main(string[] args)
{
if (args.Length == 1)
{
string fileNameOriginal = args[0];
if (fileNameOriginal.Contains(".wav"))
{
// Set encrypted file name to "%fileNameOriginal% (encrypted).wav"
string fileNameEncrypted = fileNameOriginal.Insert(fileNameOriginal.IndexOf(".wav"), " (encrypted)");
// Set decrypted file name to "%fileNameOriginal% (decrypted).wav"
string fileNameDecrypted = fileNameOriginal.Insert(fileNameOriginal.IndexOf(".wav"), " (decrypted)");
//
// Input
//
WAVFile WAVFileOriginal = new WAVFile(fileNameOriginal);
// Read WAV file header
WAVFileOriginal.ReadWAVHeader();
// Output basic WAV file info
WAVFileOriginal.GetWAVFileInfo();
//
// Encryption
//
WAVFile WAVFileEncrypted = new WAVFile(fileNameEncrypted);
// Copy original WAV file header
WAVFileEncrypted.Header = WAVFileOriginal.Header;
// Fix WAV header for encrypted file and write it
WAVFileEncrypted.CreateEncryptedWAVFile();
// Encrypt WAV file with SDS and seed value 1
SDS.EncryptWAVFile(WAVFileOriginal, WAVFileEncrypted, 1);
//
// Decryption
//
WAVFile WAVFileDecrypted = new WAVFile(fileNameDecrypted);
// Copy original WAV file header
WAVFileDecrypted.Header = WAVFileOriginal.Header;
// Fix WAV header for decrypted file and write it
WAVFileDecrypted.CreateDecryptedWAVFile();
// Decrypt WAV file with SDS and seed value 1
SDS.DecryptWAVFile(WAVFileEncrypted, WAVFileDecrypted, 1);
}
else
{
Console.WriteLine("Please supply a correct WAV file for encryption.");
}
}
else
{
Console.WriteLine("Please supply only a WAV file for encryption.");
}
}
