init commit

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Crypto/Paddings/Pkcs7Padding.cs

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+using Org.BouncyCastle.Security;
+
+namespace Org.BouncyCastle.Crypto.Paddings;
+
+public class Pkcs7Padding : IBlockCipherPadding
+{
+	public string PaddingName => "PKCS7";
+
+	public void Init(SecureRandom random)
+	{
+	}
+
+	public int AddPadding(byte[] input, int inOff)
+	{
+		byte b = (byte)(input.Length - inOff);
+		while (inOff < input.Length)
+		{
+			input[inOff] = b;
+			inOff++;
+		}
+		return b;
+	}
+
+	public int PadCount(byte[] input)
+	{
+		byte b = input[^1];
+		int num = b;
+		if (num < 1 || num > input.Length)
+		{
+			throw new InvalidCipherTextException("pad block corrupted");
+		}
+		for (int i = 2; i <= num; i++)
+		{
+			if (input[^i] != b)
+			{
+				throw new InvalidCipherTextException("pad block corrupted");
+			}
+		}
+		return num;
+	}
+}