Google Authenticator(谷歌身份驗證器)
什麼是認證器？怎麼對接？
Google Authenticator(谷歌身份驗證器)是谷歌推出的一個動態密令工具，它有兩種密令模式。分別是“TOTP 基於時間”、“HOTP 基於計數器”，通過手機上 簡單的設置就可以設定自己獨一的動態密令， 那麼我們怎麼將我們的程序和認證器進行對接呢？其實谷歌認證器並不是需要我們對接這個工具的API而是通過算法來決定，谷歌使用使用HMAC算法生成密令，通過基於次數或者基於時間兩個模板進行計算，因此在程序中只需要使用相同的算法即可與之匹配。
TOTP 基於時間
- HMAC算法使用固定爲HmacSHA1
- 更新時長固定爲30秒
- APP端輸入數據維度只有兩個：賬戶名稱（自己隨意填寫方便自己查看）和base32格式的key
HOTP 基於計數器
基於計數器模式是根據一個共享祕鑰K和一個C計數器進行算法計算
認證器安裝
手機需要安裝認證器：
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>
/// 初始化驗證碼生成規則
/// </summary>
/// <param name="key">祕鑰(手機使用Base32碼)</param>
/// <param name="duration">驗證碼間隔多久刷新一次（默認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>
/// 初始化驗證碼生成規則
/// </summary>
/// <param name="key">祕鑰(手機使用Base32碼)</param>
/// <param name="duration">驗證碼間隔多久刷新一次（默認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>
/// 間隔時間
/// </summary>
private long DURATION_TIME { get; set; }
/// <summary>
/// 迭代次數
/// </summary>
private long COUNTER
{
get
{
return (long)(DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalSeconds / DURATION_TIME;
}
}
/// <summary>
/// 祕鑰
/// </summary>
private string SERECT_KEY { get; set; }
/// <summary>
/// 手機端輸入的祕鑰
/// </summary>
private string SERECT_KEY_MOBILE { get; set; }
/// <summary>
/// 到期秒數
/// </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>
/// 獲取手機端祕鑰
/// </summary>
/// <returns></returns>
public string GetMobilePhoneKey()
{
if (SERECT_KEY_MOBILE == null)
throw new ArgumentNullException("SERECT_KEY_MOBILE");
return SERECT_KEY_MOBILE;
}
/// <summary>
/// 生成認證碼
/// </summary>
/// <returns>返回驗證碼</returns>
public string GenerateCode()
{
return GenerateHashedCode(SERECT_KEY, COUNTER);
}
/// <summary>
/// 按照次數生成哈希編碼
/// </summary>
/// <param name="secret">祕鑰</param>
/// <param name="iterationNumber">迭代次數</param>
/// <param name="digits">生成位數</param>
/// <returns>返回驗證碼</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, "谷歌驗證碼不正確！");
Response.Clear();
Response.Write(json);
Response.End();
}
案例地址：
