Remove unnecessary dependencies

TLSharp.Core/MTProto/Crypto/Crc32.cs

@@ -4,32 +4,42 @@ using System.Linq;
 using System.Security.Cryptography;
 using System.Text;
 using System.Threading.Tasks;
-using Ionic.Crc;
 
 namespace TLSharp.Core.MTProto.Crypto
 {
-    public class Crc32 : HashAlgorithm
+    /// <summary>
+    /// Implements a 32-bit CRC hash algorithm compatible with Zip etc.
+    /// </summary>
+    /// <remarks>
+    /// Crc32 should only be used for backward compatibility with older file formats
+    /// and algorithms. It is not secure enough for new applications.
+    /// If you need to call multiple times for the same data either use the HashAlgorithm
+    /// interface or remember that the result of one Compute call needs to be ~ (XOR) before
+    /// being passed in as the seed for the next Compute call.
+    /// </remarks>
+    public sealed class Crc32 : HashAlgorithm
     {
         public const UInt32 DefaultPolynomial = 0xedb88320u;
         public const UInt32 DefaultSeed = 0xffffffffu;
 
-        private UInt32 hash;
-        private UInt32 seed;
-        private UInt32[] table;
-        private static UInt32[] defaultTable;
+        static UInt32[] defaultTable;
+
+        readonly UInt32 seed;
+        readonly UInt32[] table;
+        UInt32 hash;
 
         public Crc32()
+            : this(DefaultPolynomial, DefaultSeed)
         {
-            table = InitializeTable(DefaultPolynomial);
-            seed = DefaultSeed;
-            hash = seed;
         }
 
         public Crc32(UInt32 polynomial, UInt32 seed)
         {
+            if (!BitConverter.IsLittleEndian)
+                throw new PlatformNotSupportedException("Not supported on Big Endian processors");
+
             table = InitializeTable(polynomial);
-            this.seed = seed;
-            hash = seed;
+            this.seed = hash = seed;
         }
 
         public override void Initialize()
@@ -37,35 +47,28 @@ namespace TLSharp.Core.MTProto.Crypto
             hash = seed;
         }
 
-        protected override void HashCore(byte[] buffer, int start, int length)
+        protected override void HashCore(byte[] array, int ibStart, int cbSize)
         {
-            hash = CalculateHash(table, hash, buffer, start, length);
+            hash = CalculateHash(table, hash, array, ibStart, cbSize);
         }
 
-        /// <summary>
-        /// Возвращает хеш в BigEndian
-        /// </summary>
-        /// <returns></returns>
         protected override byte[] HashFinal()
         {
-            byte[] hashBuffer = UInt32ToBigEndianBytes(~hash);
-            this.HashValue = hashBuffer;
+            var hashBuffer = UInt32ToBigEndianBytes(~hash);
+            HashValue = hashBuffer;
             return hashBuffer;
         }
 
-        public override int HashSize
-        {
-            get { return 32; }
-        }
+        public override int HashSize { get { return 32; } }
 
         public static UInt32 Compute(byte[] buffer)
         {
-            return ~CalculateHash(InitializeTable(DefaultPolynomial), DefaultSeed, buffer, 0, buffer.Length);
+            return Compute(DefaultSeed, buffer);
         }
 
         public static UInt32 Compute(UInt32 seed, byte[] buffer)
         {
-            return ~CalculateHash(InitializeTable(DefaultPolynomial), seed, buffer, 0, buffer.Length);
+            return Compute(DefaultPolynomial, seed, buffer);
         }
 
         public static UInt32 Compute(UInt32 polynomial, UInt32 seed, byte[] buffer)
@@ -73,20 +76,20 @@ namespace TLSharp.Core.MTProto.Crypto
             return ~CalculateHash(InitializeTable(polynomial), seed, buffer, 0, buffer.Length);
         }
 
-        private static UInt32[] InitializeTable(UInt32 polynomial)
+        static UInt32[] InitializeTable(UInt32 polynomial)
         {
             if (polynomial == DefaultPolynomial && defaultTable != null)
                 return defaultTable;
 
-            UInt32[] createTable = new UInt32[256];
-            for (int i = 0; i < 256; i++)
+            var createTable = new UInt32[256];
+            for (var i = 0; i < 256; i++)
             {
-                UInt32 entry = (UInt32)i;
-                for (int j = 0; j < 8; j++)
+                var entry = (UInt32)i;
+                for (var j = 0; j < 8; j++)
                     if ((entry & 1) == 1)
                         entry = (entry >> 1) ^ polynomial;
                     else
-                        entry = entry >> 1;
+                        entry >>= 1;
                 createTable[i] = entry;
             }
 
@@ -96,25 +99,23 @@ namespace TLSharp.Core.MTProto.Crypto
             return createTable;
         }
 
-        private static UInt32 CalculateHash(UInt32[] table, UInt32 seed, byte[] buffer, int start, int size)
+        static UInt32 CalculateHash(UInt32[] table, UInt32 seed, IList<byte> buffer, int start, int size)
         {
-            UInt32 crc = seed;
-            for (int i = start; i < size; i++)
-                unchecked
-                {
-                    crc = (crc >> 8) ^ table[buffer[i] ^ crc & 0xff];
-                }
-            return crc;
+            var hash = seed;
+            for (var i = start; i < start + size; i++)
+                hash = (hash >> 8) ^ table[buffer[i] ^ hash & 0xff];
+            return hash;
         }
 
-        private byte[] UInt32ToBigEndianBytes(UInt32 x)
+        static byte[] UInt32ToBigEndianBytes(UInt32 uint32)
         {
-            return new byte[] {
-                (byte)((x >> 24) & 0xff),
-                (byte)((x >> 16) & 0xff),
-                (byte)((x >> 8) & 0xff),
-                (byte)(x & 0xff)
-            };
+            var result = BitConverter.GetBytes(uint32);
+
+            if (BitConverter.IsLittleEndian)
+                Array.Reverse(result);
+
+            return result;
         }
     }
+
 }