我有一个从C#生成SHA1线索，但不能在PHP中实现

using System;
using System.Security.Cryptography;
using System.Text;

public class SHA1Generator
{
    public static string GenerateSHA1(string input)
    {
        using (SHA1Managed sha1 = new SHA1Managed())
        {
            byte[] inputBytes = Encoding.UTF8.GetBytes(input);
            byte[] hashBytes = sha1.ComputeHash(inputBytes);

            StringBuilder sb = new StringBuilder();
            foreach (byte b in hashBytes)
            {
                sb.Append(b.ToString("x2"));
            }

            return sb.ToString();
        }
    }
}

$input = "your_input_string";
$sha1 = sha1($input);

echo $sha1;