Add missing documentation for DecryptionLimit

Author: Remo Gloor

src/ICSharpCode.SharpZipLib/Zip/Compression/Streams/InflaterInputStream.cs

@@ -95,6 +95,14 @@ public int Available
 			set { available = value; }
 		}
 
+		/// <summary>
+		/// A limitation how much data is decrypted. If null all the data in the input buffer will be decrypted.
+		/// Setting limit is important in case the HMAC has to be calculated for each zip entry. In this case
+		/// it is not possible to decrypt all available data in the input buffer. In this case only the data
+		/// belonging to the current zip entry must be decrypted so that the HMAC is correctly calculated. 
+		/// </summary>
+		internal int? DecryptionLimit { get; set; }
+
 		/// <summary>
 		/// Call <see cref="Inflater.SetInput(byte[], int, int)"/> passing the current clear text buffer contents.
 		/// </summary>
@@ -303,18 +311,16 @@ public ICryptoTransform CryptoTransform
 
 		private int CalculateDecryptionSize(int availableBufferSize)
 		{
-			int size = DecryptSize ?? availableBufferSize;
+			int size = DecryptionLimit ?? availableBufferSize;
 			size = Math.Min(size, availableBufferSize);
-			if (DecryptSize.HasValue)
+			if (DecryptionLimit.HasValue)
 			{
-				DecryptSize -= size;
+				DecryptionLimit -= size;
 			}
 
 			return size;
 		}
 
-		public int? DecryptSize { get; set; }
-
 		#region Instance Fields
 
 		private int rawLength;

src/ICSharpCode.SharpZipLib/Zip/ZipInputStream.cs

@@ -611,7 +611,7 @@ private int InitialRead(byte[] destination, int offset, int count)
 					// The AES data has saltLen+AESPasswordVerifyLength bytes as a header, and AESAuthCodeLength bytes
 					// as a footer.
 					csize -= (saltLen + ZipConstants.AESPasswordVerifyLength + ZipConstants.AESAuthCodeLength);
-					inputBuffer.DecryptSize = (int)csize;
+					inputBuffer.DecryptionLimit = (int)csize;
 					inputBuffer.CryptoTransform = decryptor;
 					this.cryptoTransform = decryptor;
 				}