Google Authenticator(谷歌身份验证器)C#版
杜弘光
Google Authenticator(谷歌身份验证器)
什么是认证器？怎么对接？
Google Authenticator(谷歌身份验证器)是谷歌推出的一个动态密令工具，它有两种密令模式。分别是“TOTP 基于时间”、“HOTP 基于计数器”，通过手机上 简单的设置就可以设定自己独一的动态密令， 那么我们怎么将我们的程序和认证器进行对接呢？其实谷歌认证器并不是需要我们对接这个工具的API而是通过算法来决定，谷歌使用使用HMAC算法生成密令，通过基于次数或者基于时间两个模板进行计算，因此在程序中只需要使用相同的算法即可与之匹配。
TOTP 基于时间
- HMAC算法使用固定为HmacSHA1
- 更新时长固定为30秒
- APP端输入数据维度只有两个：账户名称（自己随意填写方便自己查看）和base32格式的key
HOTP 基于计数器
基于计数器模式是根据一个共享秘钥K和一个C计数器进行算法计算
认证器安装
手机需要安装认证器：
1、Base32.cs
using System;
namespace GoogleAuthorization
{
public static class Base32
{
public static byte[] ToBytes(string input)
{
if (string.IsNullOrEmpty(input))
{
throw new ArgumentNullException("input");
}
input = input.TrimEnd('=');
int byteCount = input.Length * 5 / 8;
byte[] returnArray = new byte[byteCount];
byte curByte = 0, bitsRemaining = 8;
int mask = 0, arrayIndex = 0;
foreach (char c in input)
{
int cValue = CharToValue(c);
if (bitsRemaining > 5)
{
mask = cValue << (bitsRemaining - 5);
curByte = (byte)(curByte | mask);
bitsRemaining -= 5;
}
else
{
mask = cValue >> (5 - bitsRemaining);
curByte = (byte)(curByte | mask);
returnArray[arrayIndex++] = curByte;
curByte = (byte)(cValue << (3 + bitsRemaining));
bitsRemaining += 3;
}
}
if (arrayIndex != byteCount)
{
returnArray[arrayIndex] = curByte;
}
return returnArray;
}
public static string ToString(byte[] input)
{
if (input == null || input.Length == 0)
{
throw new ArgumentNullException("input");
}
int charCount = (int)Math.Ceiling(input.Length / 5d) * 8;
char[] returnArray = new char[charCount];
byte nextChar = 0, bitsRemaining = 5;
int arrayIndex = 0;
foreach (byte b in input)
{
nextChar = (byte)(nextChar | (b >> (8 - bitsRemaining)));
returnArray[arrayIndex++] = ValueToChar(nextChar);
if (bitsRemaining < 4)
{
nextChar = (byte)((b >> (3 - bitsRemaining)) & 31);
returnArray[arrayIndex++] = ValueToChar(nextChar);
bitsRemaining += 5;
}
bitsRemaining -= 3;
nextChar = (byte)((b << bitsRemaining) & 31);
}
if (arrayIndex != charCount)
{
returnArray[arrayIndex++] = ValueToChar(nextChar);
while (arrayIndex != charCount) returnArray[arrayIndex++] = '=';
}
return new string(returnArray);
}
private static int CharToValue(char c)
{
var value = (int)c;
if (value < 91 && value > 64)
{
return value - 65;
}
if (value < 56 && value > 49)
{
return value - 24;
}
if (value < 123 && value > 96)
{
return value - 97;
}
throw new ArgumentException("Character is not a Base32 character.", "c");
}
private static char ValueToChar(byte b)
{
if (b < 26)
{
return (char)(b + 65);
}
if (b < 32)
{
return (char)(b + 24);
}
throw new ArgumentException("Byte is not a value Base32 value.", "b");
}
}
}
2、GoogleAuthenticator.cs
using GoogleAuthorization;
using System;
using System.Security.Cryptography;
using System.Text;
namespace GoogleAuthenticator
{
public class GoogleAuthenticator
{
/// <summary>
/// 初始化验证码生成规则
/// </summary>
/// <param name="key">秘钥(手机使用Base32码)</param>
/// <param name="duration">验证码间隔多久刷新一次（默认30秒和google同步）</param>
public GoogleAuthenticator(string key)
{
this.SERECT_KEY = key;
this.SERECT_KEY_MOBILE = Base32.ToString(Encoding.UTF8.GetBytes(key));
this.DURATION_TIME = 30;
}
/// <summary>
/// 初始化验证码生成规则
/// </summary>
/// <param name="key">秘钥(手机使用Base32码)</param>
/// <param name="duration">验证码间隔多久刷新一次（默认30秒和google同步）</param>
public GoogleAuthenticator(long duration = 30, string key = "test")
{
this.SERECT_KEY = key;
this.SERECT_KEY_MOBILE = Base32.ToString(Encoding.UTF8.GetBytes(key));
this.DURATION_TIME = duration;
}
/// <summary>
/// 间隔时间
/// </summary>
private long DURATION_TIME { get; set; }
/// <summary>
/// 迭代次数
/// </summary>
private long COUNTER
{
get
{
return (long)(DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalSeconds / DURATION_TIME;
}
}
/// <summary>
/// 秘钥
/// </summary>
private string SERECT_KEY { get; set; }
/// <summary>
/// 手机端输入的秘钥
/// </summary>
private string SERECT_KEY_MOBILE { get; set; }
/// <summary>
/// 到期秒数
/// </summary>
public long EXPIRE_SECONDS
{
get
{
return (DURATION_TIME - (long)(DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalSeconds % DURATION_TIME);
}
}
/// <summary>
/// 获取手机端秘钥
/// </summary>
/// <returns></returns>
public string GetMobilePhoneKey()
{
if (SERECT_KEY_MOBILE == null)
throw new ArgumentNullException("SERECT_KEY_MOBILE");
return SERECT_KEY_MOBILE;
}
/// <summary>
/// 生成认证码
/// </summary>
/// <returns>返回验证码</returns>
public string GenerateCode()
{
return GenerateHashedCode(SERECT_KEY, COUNTER);
}
/// <summary>
/// 按照次数生成哈希编码
/// </summary>
/// <param name="secret">秘钥</param>
/// <param name="iterationNumber">迭代次数</param>
/// <param name="digits">生成位数</param>
/// <returns>返回验证码</returns>
private string GenerateHashedCode(string secret, long iterationNumber, int digits = 6)
{
byte[] counter = BitConverter.GetBytes(iterationNumber);
if (BitConverter.IsLittleEndian)
Array.Reverse(counter);
byte[] key = Encoding.ASCII.GetBytes(secret);
HMACSHA1 hmac = new HMACSHA1(key, true);
byte[] hash = hmac.ComputeHash(counter);
int offset = hash[hash.Length - 1] & 0xf;
int binary =
((hash[offset] & 0x7f) << 24)
| ((hash[offset + 1] & 0xff) << 16)
| ((hash[offset + 2] & 0xff) << 8)
| (hash[offset + 3] & 0xff);
int password = binary % (int)Math.Pow(10, digits); // 6 digits
return password.ToString(new string('0', digits));
}
}
}
3、使用方法
string user_Code = Request["Google_Code"].ToString();
string google_key = Common.PDDCommon.GetCode_GoogleAuthenticator(phone);
if (string.IsNullOrEmpty(googleCode) || google_key.ToUpper() != googleCode.ToUpper())
{
json = SerializerJson.SuccessFlagToJson(0, "谷歌验证码不正确！");
Response.Clear();
Response.Write(json);
Response.End();
}案例地址：
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