Java实现谷歌身份验证器-蒲公英云

Java实现谷歌身份验证器

生成一个随机秘钥

public static String generateSecretKey() throws NoSuchAlgorithmException {

    SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
    sr.setSeed(Base64.decodeBase64("fooabrbalabala"));
    byte[] buffer = sr.generateSeed(10);
    Base32 codec = new Base32();
    byte[] bEncodedKey = codec.encode(buffer);
    return new String(bEncodedKey);
}

生成二维码

public static String getQRBarcode(String user, String secret, String issuer) {

    String format = "otpauth://totp/%s?secret=%s&issuer=%s";
    return String.format(format, user, secret, issuer);
}

扫码添加
根据服务端生成的二维码字符串生成二维码图片，用户在身份验真器扫码添加。
e.g.

otpauth://totp/yimcarson?secret=VIABPOEXKBBMLZD2&issuer=CSDN

身份验证器二维码

Google身份验证器截屏

生成验证码
身份验证器每个30秒更新一次验证码，服务端校验时根据系统时间和密钥生成验证码。

public static int generateCode(byte[] key, long t) throws NoSuchAlgorithmException, InvalidKeyException {

    byte[] data = new byte[8];
    long value = t;
    for (int i = 8; i-- > 0; value >>>= 8) { 
        data[i] = (byte) value;
    }
    SecretKeySpec signKey = new SecretKeySpec(key, "HmacSHA1");
    Mac mac = Mac.getInstance("HmacSHA1");
    mac.init(signKey);
    byte[] hash = mac.doFinal(data);
    int offset = hash[20 - 1] & 0xF;
    // We're using a long because Java hasn't got unsigned int.
    long truncatedHash = 0;
    for (int i = 0; i < 4; ++i) { 
        truncatedHash <<= 8;
        // We are dealing with signed bytes:
        // we just keep the first byte.
        truncatedHash |= (hash[offset + i] & 0xFF);
    }
    truncatedHash &= 0x7FFFFFFF;
    truncatedHash %= 1000000;
    return (int) truncatedHash;
}

@Test

public void generateCode() throws InvalidKeyException, NoSuchAlgorithmException { 
    byte[] key = new Base32().decode("H3GKOORXVD76URAB");
    long t = (System.currentTimeMillis() / 1000L) / 30L;
    int code = GoogleAuthenticator.generateCode(key, t);
    System.out.println(code);
}

校验验证码
为了避免用户输入、网路等延时因素引起的校验问题，服务端通常会根据时间校验多个值。

/* 最多可偏移的时间 default 3 - max 17 /

int window_size = 3;
public boolean checkCode(String secret, long code, long timeMsec) { 
    Base32 codec = new Base32();
    byte[] decodedKey = codec.decode(secret);
    long t = (timeMsec / 1000L) / 30L;
    for (int i = -window_size; i <= window_size; ++i) { 
        long hash;
        try { 
            hash = generateCode(decodedKey, t + i);
        } catch (Exception e) { 
            e.printStackTrace();
            throw new RuntimeException(e.getMessage());
        }
        if (hash == code) { 
            return true;
        }
    }
    return false;
}