TLSharp and Tests

TLSharp.Core/MTProto/Crypto/Crc32.cs

@@ -0,0 +1,104 @@
+using System;
+using System.Collections.Generic;
+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 {
+        public const UInt32 DefaultPolynomial = 0xedb88320u;
+        public const UInt32 DefaultSeed = 0xffffffffu;
+
+        private UInt32 hash;
+        private UInt32 seed;
+        private UInt32[] table;
+        private static UInt32[] defaultTable;
+
+        public Crc32() {
+            table = InitializeTable(DefaultPolynomial);
+            seed = DefaultSeed;
+            hash = seed;
+        }
+
+        public Crc32(UInt32 polynomial, UInt32 seed) {
+            table = InitializeTable(polynomial);
+            this.seed = seed;
+            hash = seed;
+        }
+
+        public override void Initialize() {
+            hash = seed;
+        }
+
+        protected override void HashCore(byte[] buffer, int start, int length) {
+            hash = CalculateHash(table, hash, buffer, start, length);
+        }
+
+        /// <summary>
+        /// Возвращает хеш в BigEndian
+        /// </summary>
+        /// <returns></returns>
+        protected override byte[] HashFinal() {
+            byte[] hashBuffer = UInt32ToBigEndianBytes(~hash);
+            this.HashValue = hashBuffer;
+            return hashBuffer;
+        }
+
+        public override int HashSize {
+            get { return 32; }
+        }
+
+        public static UInt32 Compute(byte[] buffer) {
+            return ~CalculateHash(InitializeTable(DefaultPolynomial), DefaultSeed, buffer, 0, buffer.Length);
+        }
+
+        public static UInt32 Compute(UInt32 seed, byte[] buffer) {
+            return ~CalculateHash(InitializeTable(DefaultPolynomial), seed, buffer, 0, buffer.Length);
+        }
+
+        public static UInt32 Compute(UInt32 polynomial, UInt32 seed, byte[] buffer) {
+            return ~CalculateHash(InitializeTable(polynomial), seed, buffer, 0, buffer.Length);
+        }
+
+        private static UInt32[] InitializeTable(UInt32 polynomial) {
+            if (polynomial == DefaultPolynomial && defaultTable != null)
+                return defaultTable;
+
+            UInt32[] createTable = new UInt32[256];
+            for (int i = 0; i < 256; i++) {
+                UInt32 entry = (UInt32)i;
+                for (int j = 0; j < 8; j++)
+                    if ((entry & 1) == 1)
+                        entry = (entry >> 1) ^ polynomial;
+                    else
+                        entry = entry >> 1;
+                createTable[i] = entry;
+            }
+
+            if (polynomial == DefaultPolynomial)
+                defaultTable = createTable;
+
+            return createTable;
+        }
+
+        private static UInt32 CalculateHash(UInt32[] table, UInt32 seed, 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;
+        }
+
+        private byte[] UInt32ToBigEndianBytes(UInt32 x) {
+            return new byte[] {
+			    (byte)((x >> 24) & 0xff),
+			    (byte)((x >> 16) & 0xff),
+			    (byte)((x >> 8) & 0xff),
+			    (byte)(x & 0xff)
+		    };
+        }
+    }
+}