c# - 通缉 : C# hash algorithm that returns UInt16?

Question

我需要一个哈希算法，它接受一个字符串并返回一个可以存储在 UInt16 中的数字。 .我需要它来计算一个小的校验和数。

.Net 有这方面的算法吗？

Answer 1

也许您正在寻找crc16 . Here是一个使用 byte[] 作为输入的示例，也许您可​​以修改它以改为处理字符。


为下一个人添加了一些代码:
用法:ushort hash = Crc16.ComputeHash("Hello World!");

using System;

/// <summary>
/// Creates a checksum as a ushort / UInt16.
/// </summary>
public class Crc16
{
    const ushort polynomial = 0xA001;
    ushort[] table = new ushort[256];

    /// <summary>
    /// Initializes a new instance of the <see cref="Crc16"/> class.
    /// </summary>
    public Crc16()
    {
        ushort value;
        ushort temp;
        for (ushort i = 0; i < table.Length; ++i)
        {
            value = 0;
            temp = i;
            for (byte j = 0; j < 8; ++j)
            {
                if (((value ^ temp) & 0x0001) != 0)
                {
                    value = (ushort)((value >> 1) ^ polynomial);
                }
                else
                {
                    value >>= 1;
                }
                temp >>= 1;
            }
            table[i] = value;
        }
    }

    /// <summary>
    /// Computes the hash.
    /// </summary>
    /// <param name="input">The input.</param>
    /// <returns></returns>
    public static ushort ComputeHash(string input)
    {
        if(input == null)
        {
            input = "";
        }

        Crc16 crc = new Crc16();
        byte[] bytes = Encoding.UTF8.GetBytes(input);
        return crc.ComputeChecksum(bytes);
    }

    /// <summary>
    /// Computes the checksum.
    /// </summary>
    /// <param name="bytes">The bytes.</param>
    /// <returns>The checkum.</returns>
    public ushort ComputeChecksum(byte[] bytes)
    {
        ushort crc = 0;
        for (int i = 0; i < bytes.Length; ++i)
        {
            byte index = (byte)(crc ^ bytes[i]);
            crc = (ushort)((crc >> 8) ^ table[index]);
        }
        return crc;
    }

    /// <summary>
    /// Computes the checksum bytes.
    /// </summary>
    /// <param name="bytes">The bytes.</param>
    /// <returns>The checksum.</returns>
    public byte[] ComputeChecksumBytes(byte[] bytes)
    {
        ushort crc = ComputeChecksum(bytes);
        return BitConverter.GetBytes(crc);
    }
}