Table of Contents

Class CyclicRedundancyCheck32

Namespace
Cuemon.Security
Assembly
Cuemon.Core.dll

Provides a CRC-32 implementation of the CRC (Cyclic Redundancy Check) checksum algorithm for 32-bit hash values. This class cannot be inherited.

public sealed class CyclicRedundancyCheck32 : CyclicRedundancyCheck, IHash, IConfigurable<CyclicRedundancyCheckOptions>
Inheritance
CyclicRedundancyCheck32
Implements
Inherited Members

Examples

The following example shows how to compute a CRC-32 checksum with the common reflected configuration.

using System;
using System.Text;
using Cuemon;
using Cuemon.Security;

namespace MyApp.Examples;

public static class CyclicRedundancyCheck32Example
{
    public static void Demonstrate()
    {
        var checksum = new CyclicRedundancyCheck32(setup: options =>
        {
            options.ByteOrder = Endianness.BigEndian;
            options.ReflectInput = true;
            options.ReflectOutput = true;
        });

        HashResult result = checksum.ComputeHash(Encoding.ASCII.GetBytes("123456789"));

        Console.WriteLine(result.ToHexadecimalString().ToLowerInvariant());
        Console.WriteLine(checksum.InitialValue);
        Console.WriteLine(checksum.FinalXor);

        var alternate = new CyclicRedundancyCheck32(polynomial: 0xEDB88320, initialValue: 0xFFFFFFFF, finalXor: 0xFFFFFFFF);
        Console.WriteLine(alternate.ComputeHash("Cuemon").ToBase64String());
    }
}

Constructors

CyclicRedundancyCheck32(uint, uint, uint, Action<CyclicRedundancyCheckOptions>)

Initializes a new instance of the CyclicRedundancyCheck32 class.

public CyclicRedundancyCheck32(uint polynomial = 79764919, uint initialValue = 4294967295, uint finalXor = 4294967295, Action<CyclicRedundancyCheckOptions> setup = null)

Parameters

polynomial uint

This is a binary value that should be specified as a hexadecimal number. Default is 0x4C11DB7.

initialValue uint

This parameter specifies the initial value of the register when the algorithm starts. Default is 0xFFFFFFFF.

finalXor uint

This is an W-bit value that should be specified as a hexadecimal number. Default is 0xFFFFFFFF.

setup Action<CyclicRedundancyCheckOptions>

The CyclicRedundancyCheckOptions which may be configured.

Methods

ComputeHash(byte[])

Computes the hash value for the specified byte[].

public override HashResult ComputeHash(byte[] input)

Parameters

input byte[]

The byte[] to compute the hash code for.

Returns

HashResult

A HashResult containing the computed hash code of the specified input.

Remarks

Inspiration and praises goes to http://www.sunshine2k.de/articles/coding/crc/understanding_crc.html

PolynomialIndexInitializer(byte)

Returns the initial value for the specified index of the polynomial LookupTable.

protected override ulong PolynomialIndexInitializer(byte index)

Parameters

index byte

The index of the array of polynomial values ranging from 0 to 255.

Returns

ulong

The initial value for the specified index.

PolynomialSlotCalculator(ref ulong, ulong)

Computes the polynomial checksum value in steps of 8 (0-7) x 256 (0-255) giving a total of 2048 times.

protected override void PolynomialSlotCalculator(ref ulong checksum, ulong polynomial)

Parameters

checksum ulong

The checksum that is iterated 8 times (0-7) in 256 steps (0-255).

polynomial ulong

The polynomial value.

See Also

CyclicRedundancyCheck
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