X923Padding
A padder that adds X9.23 padding to a block - if a SecureRandom is passed in random padding is assumed,
otherwise padding with zeros is used.
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities;
using System;
namespace Org.BouncyCastle.Crypto.Paddings
{
public class X923Padding : IBlockCipherPadding
{
private SecureRandom m_random;
public string PaddingName => "X9.23";
public void Init(SecureRandom random)
{
m_random = random;
}
public int AddPadding(byte[] input, int inOff)
{
int num = input.Length - inOff;
if (num > 1) {
if (m_random == null)
Arrays.Fill(input, inOff, input.Length - 1, 0);
else
m_random.NextBytes(input, inOff, num - 1);
}
input[input.Length - 1] = (byte)num;
return num;
}
public int AddPadding(Span<byte> block, int position)
{
int num = block.Length - position;
if (num > 1) {
Span<byte> buffer = block.Slice(position, block.Length - 1 - position);
if (m_random == null)
buffer.Fill(0);
else
m_random.NextBytes(buffer);
}
block[block.Length - 1] = (byte)num;
return num;
}
public int PadCount(byte[] input)
{
int num = input[input.Length - 1];
if (((input.Length - num) | (num - 1)) >> 31 != 0)
throw new InvalidCipherTextException("pad block corrupted");
return num;
}
public int PadCount(ReadOnlySpan<byte> block)
{
int num = block[block.Length - 1];
if (((block.Length - num) | (num - 1)) >> 31 != 0)
throw new InvalidCipherTextException("pad block corrupted");
return num;
}
}
}