diff --git a/Crypto/src/crypto/encodings/Pkcs1Encoding.cs b/Crypto/src/crypto/encodings/Pkcs1Encoding.cs
new file mode 100644
index 000000000..d2225a7d4
--- /dev/null
+++ b/Crypto/src/crypto/encodings/Pkcs1Encoding.cs
@@ -0,0 +1,232 @@
+using System;
+
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Crypto.Digests;
+using Org.BouncyCastle.Security;
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Crypto.Encodings
+{
+ /**
+ * this does your basic Pkcs 1 v1.5 padding - whether or not you should be using this
+ * depends on your application - see Pkcs1 Version 2 for details.
+ */
+ public class Pkcs1Encoding
+ : IAsymmetricBlockCipher
+ {
+ /**
+ * some providers fail to include the leading zero in PKCS1 encoded blocks. If you need to
+ * work with one of these set the system property Org.BouncyCastle.Pkcs1.Strict to false.
+ */
+ public const string StrictLengthEnabledProperty = "Org.BouncyCastle.Pkcs1.Strict";
+
+ private const int HeaderLength = 10;
+
+ /**
+ * The same effect can be achieved by setting the static property directly
+ * <p>
+ * The static property is checked during construction of the encoding object, it is set to
+ * true by default.
+ * </p>
+ */
+ public static bool StrictLengthEnabled
+ {
+ get { return strictLengthEnabled[0]; }
+ set { strictLengthEnabled[0] = value; }
+ }
+
+ private static readonly bool[] strictLengthEnabled;
+
+ static Pkcs1Encoding()
+ {
+ string strictProperty = Platform.GetEnvironmentVariable(StrictLengthEnabledProperty);
+
+ strictLengthEnabled = new bool[]{ strictProperty == null || strictProperty.Equals("true")};
+ }
+
+
+ private SecureRandom random;
+ private IAsymmetricBlockCipher engine;
+ private bool forEncryption;
+ private bool forPrivateKey;
+ private bool useStrictLength;
+
+ /**
+ * Basic constructor.
+ * @param cipher
+ */
+ public Pkcs1Encoding(
+ IAsymmetricBlockCipher cipher)
+ {
+ this.engine = cipher;
+ this.useStrictLength = StrictLengthEnabled;
+ }
+
+ public IAsymmetricBlockCipher GetUnderlyingCipher()
+ {
+ return engine;
+ }
+
+ public string AlgorithmName
+ {
+ get { return engine.AlgorithmName + "/PKCS1Padding"; }
+ }
+
+ public void Init(
+ bool forEncryption,
+ ICipherParameters parameters)
+ {
+ AsymmetricKeyParameter kParam;
+ if (parameters is ParametersWithRandom)
+ {
+ ParametersWithRandom rParam = (ParametersWithRandom)parameters;
+
+ this.random = rParam.Random;
+ kParam = (AsymmetricKeyParameter)rParam.Parameters;
+ }
+ else
+ {
+ this.random = new SecureRandom();
+ kParam = (AsymmetricKeyParameter)parameters;
+ }
+
+ engine.Init(forEncryption, parameters);
+
+ this.forPrivateKey = kParam.IsPrivate;
+ this.forEncryption = forEncryption;
+ }
+
+ public int GetInputBlockSize()
+ {
+ int baseBlockSize = engine.GetInputBlockSize();
+
+ return forEncryption
+ ? baseBlockSize - HeaderLength
+ : baseBlockSize;
+ }
+
+ public int GetOutputBlockSize()
+ {
+ int baseBlockSize = engine.GetOutputBlockSize();
+
+ return forEncryption
+ ? baseBlockSize
+ : baseBlockSize - HeaderLength;
+ }
+
+ public byte[] ProcessBlock(
+ byte[] input,
+ int inOff,
+ int length)
+ {
+ return forEncryption
+ ? EncodeBlock(input, inOff, length)
+ : DecodeBlock(input, inOff, length);
+ }
+
+ private byte[] EncodeBlock(
+ byte[] input,
+ int inOff,
+ int inLen)
+ {
+ if (inLen > GetInputBlockSize())
+ throw new ArgumentException("input data too large", "inLen");
+
+ byte[] block = new byte[engine.GetInputBlockSize()];
+
+ if (forPrivateKey)
+ {
+ block[0] = 0x01; // type code 1
+
+ for (int i = 1; i != block.Length - inLen - 1; i++)
+ {
+ block[i] = (byte)0xFF;
+ }
+ }
+ else
+ {
+ random.NextBytes(block); // random fill
+
+ block[0] = 0x02; // type code 2
+
+ //
+ // a zero byte marks the end of the padding, so all
+ // the pad bytes must be non-zero.
+ //
+ for (int i = 1; i != block.Length - inLen - 1; i++)
+ {
+ while (block[i] == 0)
+ {
+ block[i] = (byte)random.NextInt();
+ }
+ }
+ }
+
+ block[block.Length - inLen - 1] = 0x00; // mark the end of the padding
+ Array.Copy(input, inOff, block, block.Length - inLen, inLen);
+
+ return engine.ProcessBlock(block, 0, block.Length);
+ }
+
+ /**
+ * @exception InvalidCipherTextException if the decrypted block is not in Pkcs1 format.
+ */
+ private byte[] DecodeBlock(
+ byte[] input,
+ int inOff,
+ int inLen)
+ {
+ byte[] block = engine.ProcessBlock(input, inOff, inLen);
+
+ if (block.Length < GetOutputBlockSize())
+ {
+ throw new InvalidCipherTextException("block truncated");
+ }
+
+ byte type = block[0];
+
+ if (type != 1 && type != 2)
+ {
+ throw new InvalidCipherTextException("unknown block type");
+ }
+
+ if (useStrictLength && block.Length != engine.GetOutputBlockSize())
+ {
+ throw new InvalidCipherTextException("block incorrect size");
+ }
+
+ //
+ // find and extract the message block.
+ //
+ int start;
+ for (start = 1; start != block.Length; start++)
+ {
+ byte pad = block[start];
+
+ if (pad == 0)
+ {
+ break;
+ }
+
+ if (type == 1 && pad != (byte)0xff)
+ {
+ throw new InvalidCipherTextException("block padding incorrect");
+ }
+ }
+
+ start++; // data should start at the next byte
+
+ if (start > block.Length || start < HeaderLength)
+ {
+ throw new InvalidCipherTextException("no data in block");
+ }
+
+ byte[] result = new byte[block.Length - start];
+
+ Array.Copy(block, start, result, 0, result.Length);
+
+ return result;
+ }
+ }
+
+}
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