首先引用这个命名空间

using System.Security.Cryptography;

//建立SHA1对象

SHA1 sha = new SHA1CryptoServiceProvider();

//将mystr转换成byte[]

ASCIIEncoding enc = new ASCIIEncoding();

byte[] dataToHash = enc.GetBytes(mystr);

//Hash运算

byte[] dataHashed = SHA1.ComputeHash(dataToHash );

//将运算结果转换成string

string hash = BitConverter.ToString(dataHashed).Replace("-", "");

return hash;