I need CRC Reverse Code for my CRC64 Checksum Coding

Question

Can someone please code me the CRC64 Reverse Algorithm in C#? I am unable to code it, can't understand anything. Thanks,

I have copied the CRC64 Checksum code from C++ and converted it into C# .NET. The entire code is displayed below:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CRC64
{
    public class cCRC64
    {
        public UInt64[] crc64_table = {
             0x0000000000000000, 0x42F0E1EBA9EA3693,
             0x85E1C3D753D46D26, 0xC711223CFA3E5BB5,
             0x493366450E42ECDF, 0x0BC387AEA7A8DA4C,
             0xCCD2A5925D9681F9, 0x8E224479F47CB76A,
             0x9266CC8A1C85D9BE, 0xD0962D61B56FEF2D,
             0x17870F5D4F51B498, 0x5577EEB6E6BB820B,
             0xDB55AACF12C73561, 0x99A54B24BB2D03F2,
             0x5EB4691841135847, 0x1C4488F3E8F96ED4,
             0x663D78FF90E185EF, 0x24CD9914390BB37C,
             0xE3DCBB28C335E8C9, 0xA12C5AC36ADFDE5A,
             0x2F0E1EBA9EA36930, 0x6DFEFF5137495FA3,
             0xAAEFDD6DCD770416, 0xE81F3C86649D3285,
             0xF45BB4758C645C51, 0xB6AB559E258E6AC2,
             0x71BA77A2DFB03177, 0x334A9649765A07E4,
             0xBD68D2308226B08E, 0xFF9833DB2BCC861D,
             0x388911E7D1F2DDA8, 0x7A79F00C7818EB3B,
             0xCC7AF1FF21C30BDE, 0x8E8A101488293D4D,
             0x499B3228721766F8, 0x0B6BD3C3DBFD506B,
             0x854997BA2F81E701, 0xC7B97651866BD192,
             0x00A8546D7C558A27, 0x4258B586D5BFBCB4,
             0x5E1C3D753D46D260, 0x1CECDC9E94ACE4F3,
             0xDBFDFEA26E92BF46, 0x990D1F49C77889D5,
             0x172F5B3033043EBF, 0x55DFBADB9AEE082C,
             0x92CE98E760D05399, 0xD03E790CC93A650A,
             0xAA478900B1228E31, 0xE8B768EB18C8B8A2,
             0x2FA64AD7E2F6E317, 0x6D56AB3C4B1CD584,
             0xE374EF45BF6062EE, 0xA1840EAE168A547D,
             0x66952C92ECB40FC8, 0x2465CD79455E395B,
             0x3821458AADA7578F, 0x7AD1A461044D611C,
             0xBDC0865DFE733AA9, 0xFF3067B657990C3A,
             0x711223CFA3E5BB50, 0x33E2C2240A0F8DC3,
             0xF4F3E018F031D676, 0xB60301F359DBE0E5,
             0xDA050215EA6C212F, 0x98F5E3FE438617BC,
             0x5FE4C1C2B9B84C09, 0x1D14202910527A9A,
             0x93366450E42ECDF0, 0xD1C685BB4DC4FB63,
             0x16D7A787B7FAA0D6, 0x5427466C1E109645,
             0x4863CE9FF6E9F891, 0x0A932F745F03CE02,
             0xCD820D48A53D95B7, 0x8F72ECA30CD7A324,
             0x0150A8DAF8AB144E, 0x43A04931514122DD,
             0x84B16B0DAB7F7968, 0xC6418AE602954FFB,
             0xBC387AEA7A8DA4C0, 0xFEC89B01D3679253,
             0x39D9B93D2959C9E6, 0x7B2958D680B3FF75,
             0xF50B1CAF74CF481F, 0xB7FBFD44DD257E8C,
             0x70EADF78271B2539, 0x321A3E938EF113AA,
             0x2E5EB66066087D7E, 0x6CAE578BCFE24BED,
             0xABBF75B735DC1058, 0xE94F945C9C3626CB,
             0x676DD025684A91A1, 0x259D31CEC1A0A732,
             0xE28C13F23B9EFC87, 0xA07CF2199274CA14,
             0x167FF3EACBAF2AF1, 0x548F120162451C62,
             0x939E303D987B47D7, 0xD16ED1D631917144,
             0x5F4C95AFC5EDC62E, 0x1DBC74446C07F0BD,
             0xDAAD56789639AB08, 0x985DB7933FD39D9B,
             0x84193F60D72AF34F, 0xC6E9DE8B7EC0C5DC,
             0x01F8FCB784FE9E69, 0x43081D5C2D14A8FA,
             0xCD2A5925D9681F90, 0x8FDAB8CE70822903,
             0x48CB9AF28ABC72B6, 0x0A3B7B1923564425,
             0x70428B155B4EAF1E, 0x32B26AFEF2A4998D,
             0xF5A348C2089AC238, 0xB753A929A170F4AB,
             0x3971ED50550C43C1, 0x7B810CBBFCE67552,
             0xBC902E8706D82EE7, 0xFE60CF6CAF321874,
             0xE224479F47CB76A0, 0xA0D4A674EE214033,
             0x67C58448141F1B86, 0x253565A3BDF52D15,
             0xAB1721DA49899A7F, 0xE9E7C031E063ACEC,
             0x2EF6E20D1A5DF759, 0x6C0603E6B3B7C1CA,
             0xF6FAE5C07D3274CD, 0xB40A042BD4D8425E,
             0x731B26172EE619EB, 0x31EBC7FC870C2F78,
             0xBFC9838573709812, 0xFD39626EDA9AAE81,
             0x3A28405220A4F534, 0x78D8A1B9894EC3A7,
             0x649C294A61B7AD73, 0x266CC8A1C85D9BE0,
             0xE17DEA9D3263C055, 0xA38D0B769B89F6C6,
             0x2DAF4F0F6FF541AC, 0x6F5FAEE4C61F773F,
             0xA84E8CD83C212C8A, 0xEABE6D3395CB1A19,
             0x90C79D3FEDD3F122, 0xD2377CD44439C7B1,
             0x15265EE8BE079C04, 0x57D6BF0317EDAA97,
             0xD9F4FB7AE3911DFD, 0x9B041A914A7B2B6E,
             0x5C1538ADB04570DB, 0x1EE5D94619AF4648,
             0x02A151B5F156289C, 0x4051B05E58BC1E0F,
             0x87409262A28245BA, 0xC5B073890B687329,
             0x4B9237F0FF14C443, 0x0962D61B56FEF2D0,
             0xCE73F427ACC0A965, 0x8C8315CC052A9FF6,
             0x3A80143F5CF17F13, 0x7870F5D4F51B4980,
             0xBF61D7E80F251235, 0xFD913603A6CF24A6,
             0x73B3727A52B393CC, 0x31439391FB59A55F,
             0xF652B1AD0167FEEA, 0xB4A25046A88DC879,
             0xA8E6D8B54074A6AD, 0xEA16395EE99E903E,
             0x2D071B6213A0CB8B, 0x6FF7FA89BA4AFD18,
             0xE1D5BEF04E364A72, 0xA3255F1BE7DC7CE1,
             0x64347D271DE22754, 0x26C49CCCB40811C7,
             0x5CBD6CC0CC10FAFC, 0x1E4D8D2B65FACC6F,
             0xD95CAF179FC497DA, 0x9BAC4EFC362EA149,
             0x158E0A85C2521623, 0x577EEB6E6BB820B0,
             0x906FC95291867B05, 0xD29F28B9386C4D96,
             0xCEDBA04AD0952342, 0x8C2B41A1797F15D1,
             0x4B3A639D83414E64, 0x09CA82762AAB78F7,
             0x87E8C60FDED7CF9D, 0xC51827E4773DF90E,
             0x020905D88D03A2BB, 0x40F9E43324E99428,
             0x2CFFE7D5975E55E2, 0x6E0F063E3EB46371,
             0xA91E2402C48A38C4, 0xEBEEC5E96D600E57,
             0x65CC8190991CB93D, 0x273C607B30F68FAE,
             0xE02D4247CAC8D41B, 0xA2DDA3AC6322E288,
             0xBE992B5F8BDB8C5C, 0xFC69CAB42231BACF,
             0x3B78E888D80FE17A, 0x7988096371E5D7E9,
             0xF7AA4D1A85996083, 0xB55AACF12C735610,
             0x724B8ECDD64D0DA5, 0x30BB6F267FA73B36,
             0x4AC29F2A07BFD00D, 0x08327EC1AE55E69E,
             0xCF235CFD546BBD2B, 0x8DD3BD16FD818BB8,
             0x03F1F96F09FD3CD2, 0x41011884A0170A41,
             0x86103AB85A2951F4, 0xC4E0DB53F3C36767,
             0xD8A453A01B3A09B3, 0x9A54B24BB2D03F20,
             0x5D45907748EE6495, 0x1FB5719CE1045206,
             0x919735E51578E56C, 0xD367D40EBC92D3FF,
             0x1476F63246AC884A, 0x568617D9EF46BED9,
             0xE085162AB69D5E3C, 0xA275F7C11F7768AF,
             0x6564D5FDE549331A, 0x279434164CA30589,
             0xA9B6706FB8DFB2E3, 0xEB46918411358470,
             0x2C57B3B8EB0BDFC5, 0x6EA7525342E1E956,
             0x72E3DAA0AA188782, 0x30133B4B03F2B111,
             0xF7021977F9CCEAA4, 0xB5F2F89C5026DC37,
             0x3BD0BCE5A45A6B5D, 0x79205D0E0DB05DCE,
             0xBE317F32F78E067B, 0xFCC19ED95E6430E8,
             0x86B86ED5267CDBD3, 0xC4488F3E8F96ED40,
             0x0359AD0275A8B6F5, 0x41A94CE9DC428066,
             0xCF8B0890283E370C, 0x8D7BE97B81D4019F,
             0x4A6ACB477BEA5A2A, 0x089A2AACD2006CB9,
             0x14DEA25F3AF9026D, 0x562E43B4931334FE,
             0x913F6188692D6F4B, 0xD3CF8063C0C759D8,
             0x5DEDC41A34BBEEB2, 0x1F1D25F19D51D821,
             0xD80C07CD676F8394, 0x9AFCE626CE85B507
        };

        /* Initialize a CRC accumulator */
        public void Init_crc(ref UInt64 crc)
        {
            crc = 0xffffffffffffffff;
        }

        /* Finish a CRC calculation */
        public void Fin_crc(ref UInt64 crc)
        {
            crc ^= 0xffffffffffffffff;
        }

        /* Accumulate some (more) bytes into a CRC */
        public void Calc_crc(ref UInt64 crc, Byte[] pbData, uint len)
        {
            /* Constant table for CRC calculation */
            uint __len = len;
            uint pos = 0;
            byte byteInput = 0;

            while (__len-- > 0)
            {
                uint __tab_index = ((uint) (crc >> 56) ^ pbData[pos++]) & 0xFF;
                crc = crc64_table[__tab_index] ^ (crc << 8);
            }
        }
    }
}

Waiting for help!

Answer 1

No.

Hashing algorithms are not reversible. You can't get back the original data, but you can get all possible sets of a specific length by calculating the hash for all possible combinations and compare to the hash that you have.

This is of course imensely calculation intensive. Just ten bytes for example gives you 1 208 925 819 614 629 174 706 176 combinations to test...