public static MemoryStream DecryptRsa(Stream inputStream, string pemKey)
{
AsymmetricKeyParameter keyParameter = ReadPem(pemKey);
var engine = new RsaEngine();
engine.Init(false, keyParameter);
var outputStream = new MemoryStream();
int inputBlockSize = engine.GetInputBlockSize();
int outputBlockSize = engine.GetOutputBlockSize();
byte[] inputBlock = new byte[inputBlockSize];
while (inputStream.Read(inputBlock, 0, inputBlock.Length) > 0)
{
byte[] outputBlock = engine.ProcessBlock(inputBlock, 0, inputBlockSize);
int requiredPadding = outputBlockSize - outputBlock.Length;
if (requiredPadding > 0)
{
byte[] paddedOutputBlock = new byte[outputBlockSize];
outputBlock.CopyTo(paddedOutputBlock, requiredPadding);
outputBlock = paddedOutputBlock;
}
outputStream.Write(outputBlock, 0, outputBlock.Length);
}
outputStream.Seek(0, SeekOrigin.Begin);
return(outputStream);
}
public static string Decrypt(string CipherText, string mod, string exp)
{
var Modulus = HelperFunctions.FromHexToByte(mod);
var Exponent = HelperFunctions.FromHexToByte(exp);
var CipherTextBytes = Convert.FromBase64String(CipherText);
var modulus = new BigInteger(1, Modulus);
var exponent = new BigInteger(1, Exponent);
var Parameters = new RsaKeyParameters(true, modulus, exponent);
var RSAengine = new RsaEngine();
RSAengine.Init(false, Parameters);
var blockSize = RSAengine.GetInputBlockSize();
var output = new List <byte>();
for (var chunkPosition = 0; chunkPosition < CipherTextBytes.Length; chunkPosition += blockSize)
{
var chunkSize = Math.Min(blockSize, CipherTextBytes.Length - chunkPosition * blockSize);
output.AddRange(RSAengine.ProcessBlock(CipherTextBytes, chunkPosition, chunkSize));
}
var output2 = output.ToArray();
var PlainText = Encoding.ASCII.GetString(output2);
return(PlainText);
}
public static byte[] Decrypt(byte[] data, AsymmetricKeyParameter privateKey)
{
if (privateKey == null || !privateKey.IsPrivate)
{
throw new ArgumentException("Not a valid decryption key");
}
// purely mathematical RSA
var engine = new RsaEngine();
// use padding
var cipher = new OaepEncoding(engine);
cipher.Init(false, privateKey);
var length = data.Length;
var blockSize = engine.GetInputBlockSize();
var plainTextBytes = new List <byte>();
for (var i = 0; i < length; i += blockSize)
{
var chunkSize = Math.Min(blockSize, length - i);
plainTextBytes.AddRange(engine.ProcessBlock(data, i, chunkSize));
}
return(plainTextBytes.ToArray());
}
public int GetBlockSize()
{
RsaEngine rsa = new RsaEngine();
rsa.Init(true, publicKey);
return(rsa.GetInputBlockSize());
}
public byte[] Decrypt(byte[] cipher)
{
RsaEngine rsa = new RsaEngine();
rsa.Init(false, privateKey);
int blockSize = rsa.GetInputBlockSize();
List <byte> output = new List <byte>();
for (int chunkPosition = 0; chunkPosition < cipher.Length; chunkPosition += blockSize)
{
int chunkSize = Math.Min(blockSize, cipher.Length - chunkPosition);
byte[] tmp = cipher.ToList().GetRange(chunkPosition, chunkSize).ToArray().Reverse().ToArray();
output.AddRange(rsa.ProcessBlock(tmp, 0, tmp.Length));
}
return(output.ToArray());
}
public byte[] Encrypt(byte[] message)
{
RsaEngine rsa = new RsaEngine();
rsa.Init(true, publicKey);
int blockSize = rsa.GetInputBlockSize();
List <byte> output = new List <byte>();
for (int chunkPosition = 0; chunkPosition < message.Length; chunkPosition += blockSize)
{
int chunkSize = Math.Min(blockSize, message.Length - (chunkPosition * blockSize));
byte[] tmp = rsa.ProcessBlock(message, chunkPosition, chunkSize);
output.AddRange(tmp);
}
return(output.ToArray());
}
/// <summary>
/// Decrypts a file with a provided decryption key.
/// </summary>
/// <param name="filePath">An encrypted file</param>
/// <param name="key">The RSA key in PEM format</param>
/// <exception cref="ArgumentNullException">When the argument filePath is null</exception>
/// <exception cref="ArgumentNullException">When the argument keyPath is null</exception>
/// <returns>A memory stream with the decrypted file</returns>
public static MemoryStream DecryptRsa(string filePath, string key)
{
if (filePath == null)
{
throw new ArgumentNullException(nameof(filePath));
}
if (key == null)
{
throw new ArgumentNullException(nameof(key));
}
AsymmetricKeyParameter keyParameter = GetKeyOrDefault(key);
RsaEngine engine = new RsaEngine();
engine.Init(false, keyParameter);
MemoryStream outputStream = new MemoryStream();
using (FileStream inputStream = File.OpenRead(filePath))
{
int inputBlockSize = engine.GetInputBlockSize();
int outputBlockSize = engine.GetOutputBlockSize();
byte[] inputBlock = new byte[inputBlockSize];
while (inputStream.Read(inputBlock, 0, inputBlock.Length) > 0)
{
byte[] outputBlock = engine.ProcessBlock(inputBlock, 0, inputBlockSize);
int requiredPadding = outputBlockSize - outputBlock.Length;
if (requiredPadding > 0)
{
byte[] paddedOutputBlock = new byte[outputBlockSize];
outputBlock.CopyTo(paddedOutputBlock, requiredPadding);
outputBlock = paddedOutputBlock;
}
outputStream.Write(outputBlock, 0, outputBlock.Length);
}
}
outputStream.Seek(0, SeekOrigin.Begin);
return(outputStream);
}
/// <summary>
/// Decrypts data using RSA methology with VisualGest PUBLIC KEY
/// </summary>
/// <param name="cipherText">string data to Decrypt</param>
/// <returns></returns>
public static string Decrypt(string cipherText, int encodingPageNumber = VGEST_ENCODING_PAGE)
{
string executableLocation = Path.GetDirectoryName(
System.Reflection.Assembly.GetExecutingAssembly().Location);
string pemFilename = Path.Combine(executableLocation, "RSAEncryption\\VGestKeys\\VGPubKey.pem");
//string pemFilename = "RSAEncryption\\VGestKeys\\VGPubKey.pem";
byte[] cipherTextBytes = Convert.FromBase64String(cipherText);
RsaKeyParameters keys;
using (var reader = File.OpenText(pemFilename))
keys = (RsaKeyParameters) new PemReader(reader).ReadObject();
// Pure mathematical RSA implementation
RsaEngine eng = new RsaEngine();
// PKCS1 v1.5 paddings
// Pkcs1Encoding eng = new Pkcs1Encoding(new RsaEngine());
// PKCS1 OAEP paddings
//OaepEncoding eng = new OaepEncoding(new RsaEngine());
eng.Init(false, keys);
int length = cipherTextBytes.Length;
int blockSize = eng.GetInputBlockSize();
List <byte> plainTextBytes = new List <byte>();
for (int chunkPosition = 0;
chunkPosition < length;
chunkPosition += blockSize)
{
int chunkSize = Math.Min(blockSize, length - chunkPosition);
plainTextBytes.AddRange(eng.ProcessBlock(
cipherTextBytes, chunkPosition, chunkSize
));
}
return(Encoding.GetEncoding(encodingPageNumber).GetString(plainTextBytes.ToArray()));
}
public byte[] Decrypt(byte[] data, AsymmetricKeyParameter key)
{
if (key == null)
{
throw new Exception("licmanPrivateKey not Found: Please check your settings in SomeResources.resx");
}
RsaEngine e = new RsaEngine();
e.Init(false, key);
int blockSize = e.GetInputBlockSize();
List <byte> output = new List <byte>();
for (int chunkPosition = 0; chunkPosition < data.Length; chunkPosition += blockSize)
{
int chunkSize = Math.Min(blockSize, data.Length -
(chunkPosition * blockSize));
output.AddRange(e.ProcessBlock(data, chunkPosition,
chunkSize));
}
return(output.ToArray());
}
