namespace com.hitrust.Security.Cryptography
{
	using System;
	using System.Security.Cryptography;

	public abstract class RC4 : SymmetricAlgorithm
	{
		private RNGCryptoServiceProvider m_RNG;

		protected RC4()
		{
			base.KeySizeValue = 0x80;
		}

		public new static RC4 Create()
		{
			return Create("ARCFOUR");
		}

		public new static RC4 Create(string AlgName)
		{
			try {
				if ((AlgName.ToUpper() == "RC4") || (AlgName.ToLower() == "org.mentalis.security.cryptography.rc4cryptoserviceprovider")) {
					return new RC4CryptoServiceProvider();
				}
				if ((AlgName.ToUpper() == "ARCFOUR") || (AlgName.ToLower() == "org.mentalis.security.cryptography.arcfourmanaged")) {
					return new ARCFourManaged();
				}
			} catch {}
			return null;
		}

		public override void GenerateIV() {}

		public override void GenerateKey()
		{
			byte[] key = new byte[this.KeySize / 8];
			this.GetRNGCSP().GetBytes(key);
			this.Key = key;
		}

		protected RNGCryptoServiceProvider GetRNGCSP()
		{
			if (this.m_RNG == null) {
				this.m_RNG = new RNGCryptoServiceProvider();
			}
			return this.m_RNG;
		}

		public override int BlockSize
		{
			get { return 8; }
			set
			{
				if ((value != 8) && (value != 0)) {
					throw new CryptographicException("RC4 is a stream cipher, not a block cipher.");
				}
			}
		}

		public override int FeedbackSize
		{
			get { throw new CryptographicException("RC4 doesn't use the feedback size property."); }
			set { throw new CryptographicException("RC4 doesn't use the feedback size property."); }
		}

		public override byte[] IV
		{
			get { return new byte[1]; }
			set
			{
				if ((value != null) && (value.Length > 1)) {
					throw new CryptographicException("RC4 doesn't use an Initialization Vector.");
				}
			}
		}

		public override KeySizes[] LegalBlockSizes
		{
			get { return new KeySizes[] {new KeySizes(8, 8, 0)}; }
		}

		public override KeySizes[] LegalKeySizes
		{
			get { return new KeySizes[] {new KeySizes(8, 0x800, 8)}; }
		}

		public override CipherMode Mode
		{
			get { return CipherMode.OFB; }
			set
			{
				if (value != CipherMode.OFB) {
					throw new CryptographicException("RC4 only supports OFB.");
				}
			}
		}

		public override PaddingMode Padding
		{
			get { return PaddingMode.None; }
			set
			{
				if (value != PaddingMode.None) {
					throw new CryptographicException("RC4 is a stream cipher, not a block cipher.");
				}
			}
		}
	}
}