Add ZipConstants entries for AESAuthCodeLength and AESPasswordVerifyLength, so the values can be shared

Author: Numpsy

src/ICSharpCode.SharpZipLib/Encryption/ZipAESStream.cs

@@ -37,7 +37,7 @@ public ZipAESStream(Stream stream, ZipAESTransform transform, CryptoStreamMode m
 		}
 
 		// The final n bytes of the AES stream contain the Auth Code.
-		private const int AUTH_CODE_LENGTH = 10;
+		private const int AUTH_CODE_LENGTH = Zip.ZipConstants.AESAuthCodeLength;
 
 		// Blocksize is always 16 here, even for AES-256 which has transform.InputBlockSize of 32.
 		private const int CRYPTO_BLOCK_SIZE = 16;

src/ICSharpCode.SharpZipLib/Encryption/ZipAESTransform.cs

@@ -33,8 +33,6 @@ static class HashAlgorithmName
 		}
 #endif
 
-		private const int PWD_VER_LENGTH = 2;
-
 		// WinZip use iteration count of 1000 for PBKDF2 key generation
 		private const int KEY_ROUNDS = 1000;
 
@@ -84,7 +82,7 @@ public ZipAESTransform(string key, byte[] saltBytes, int blockSize, bool writeMo
 
 			// Use empty IV for AES
 			_encryptor = rm.CreateEncryptor(key1bytes, new byte[16]);
-			_pwdVerifier = pdb.GetBytes(PWD_VER_LENGTH);
+			_pwdVerifier = pdb.GetBytes(Zip.ZipConstants.AESPasswordVerifyLength);
 			//
 			_hmacsha1 = IncrementalHash.CreateHMAC(HashAlgorithmName.SHA1, key2bytes);
 			_writeMode = writeMode;

src/ICSharpCode.SharpZipLib/Zip/ZipConstants.cs

@@ -345,6 +345,16 @@ public static class ZipConstants
 		[Obsolete("Use CryptoHeaderSize instead")]
 		public const int CRYPTO_HEADER_SIZE = 12;
 
+		/// <summary>
+		/// The number of bytes in the WinZipAes Auth Code.
+		/// </summary>
+		internal const int AESAuthCodeLength = 10;
+
+		/// <summary>
+		/// The number of bytes in the password verifier for WinZipAes.
+		/// </summary>
+		internal const int AESPasswordVerifyLength = 2;
+
 		/// <summary>
 		/// The size of the Zip64 central directory locator.
 		/// </summary>