最近公司的数据统计平台报了大量ssl证书错误.类似于这种
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| javax.net.ssl.sslhandshakeexception:
com.android.org.bouncycastle.jce.exception.extcertpathvalidatorexception:
could not validate certificate:
current time: mon jan 04 13:33:18 格林尼治标准时间+0800 2010,
validation time: fri mar 08 20:00:00 格林尼治标准时间+0800 2013
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拿着上报信息中的链接在浏览器打开,并没有证书错误,我们的后台也并没有做什么自定义证书,完全是系统默认的SSL Context.
结合异常信息,并检查对应域名的证书信息,可以断定是手机系统时间修改后,超出证书有效期,导致证书校验错误.
虽说这本质上是一个安全性措施,但是修改系统时间的场景也无法完全避免.初步推测是某些云测平台的系统时间有误导致.
信任所有证书肯定是不行的.不仅有安全问题,同时各种app安全扫描平台基本上都把这个当高危项目.
那么问题来了,如何单单将证书时间错误的问题忽略掉呢?
一开始我是这么干的,检测到指定Exception时,忽略掉.
关键代码都在这个自定义的TrustManager里面.在checkServerTrusted中对异常类型进行检查.
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| final TrustManager[] trustAllCerts = new TrustManager[]{new X509TrustManager() {
@Override
public void checkClientTrusted(
java.security.cert.X509Certificate[] chain,
String authType) throws CertificateException {
}
@Override
public void checkServerTrusted(
java.security.cert.X509Certificate[] chain,
String authType) throws CertificateException {
try {
defaultTrustManager.checkServerTrusted(chain, authType);
} catch (CertificateException e) {
e.printStackTrace();
Throwable t = e;
while (t != null) {
if (t instanceof CertificateExpiredException
|| t instanceof CertificateNotYetValidException)
return;
t = t.getCause();
}
throw e;
}
}
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这里面有个问题:
通常这个证书链是包含多个证书的,如果一检测到有效期相关的异常就return,会导致后面的所有证书都被信任了.不太安全.
更坑爹的是,实际使用中抛出来的是CertPathValidatorException!!!看这个异常的描述,不能保证触发它的一定是有效期问题.
既然TrustManager不能做文章了.那就再往下一层.在X509Certificate上看看吧.
X509Certificate有很多方法,其中和本文相关的checkValidity()**和checkValidity(Date date)**就是证书有效期检查相关的方法.
于是用自定义的X509Certificate封装一层,把这两个方法给屏蔽掉.就可以既不影响其他的证书校验,就可以忽略日期异常了.
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| private class EternalCertificate extends X509Certificate {
private final X509Certificate originalCertificate;
public EternalCertificate(X509Certificate originalCertificate) {
this.originalCertificate = originalCertificate;
}
@Override
public void checkValidity() throws CertificateExpiredException, CertificateNotYetValidException {
}
@Override
public void checkValidity(Date date) throws CertificateExpiredException, CertificateNotYetValidException {
}
@Override
public int getVersion() {
return originalCertificate.getVersion();
}
@Override
public BigInteger getSerialNumber() {
return originalCertificate.getSerialNumber();
}
@Override
public Principal getIssuerDN() {
return originalCertificate.getIssuerDN();
}
@Override
public Principal getSubjectDN() {
return originalCertificate.getSubjectDN();
}
@Override
public Date getNotBefore() {
return originalCertificate.getNotBefore();
}
@Override
public Date getNotAfter() {
return originalCertificate.getNotAfter();
}
@Override
public byte[] getTBSCertificate() throws CertificateEncodingException {
return originalCertificate.getTBSCertificate();
}
@Override
public byte[] getSignature() {
return originalCertificate.getSignature();
}
@Override
public String getSigAlgName() {
return originalCertificate.getSigAlgName();
}
@Override
public String getSigAlgOID() {
return originalCertificate.getSigAlgOID();
}
@Override
public byte[] getSigAlgParams() {
return originalCertificate.getSigAlgParams();
}
@Override
public boolean[] getIssuerUniqueID() {
return originalCertificate.getIssuerUniqueID();
}
@Override
public boolean[] getSubjectUniqueID() {
return originalCertificate.getSubjectUniqueID();
}
@Override
public boolean[] getKeyUsage() {
return originalCertificate.getKeyUsage();
}
@Override
public int getBasicConstraints() {
return originalCertificate.getBasicConstraints();
}
@Override
public byte[] getEncoded() throws CertificateEncodingException {
return originalCertificate.getEncoded();
}
@Override
public void verify(PublicKey key) throws CertificateException, NoSuchAlgorithmException, InvalidKeyException, NoSuchProviderException,
SignatureException {
originalCertificate.verify(key);
}
@Override
public void verify(PublicKey key, String sigProvider) throws CertificateException, NoSuchAlgorithmException, InvalidKeyException,
NoSuchProviderException, SignatureException {
originalCertificate.verify(key, sigProvider);
}
@Override
public String toString() {
return originalCertificate.toString();
}
@Override
public PublicKey getPublicKey() {
return originalCertificate.getPublicKey();
}
@Override
public Set<String> getCriticalExtensionOIDs() {
return originalCertificate.getCriticalExtensionOIDs();
}
@Override
public byte[] getExtensionValue(String oid) {
return originalCertificate.getExtensionValue(oid);
}
@Override
public Set<String> getNonCriticalExtensionOIDs() {
return originalCertificate.getNonCriticalExtensionOIDs();
}
@Override
public boolean hasUnsupportedCriticalExtension() {
return originalCertificate.hasUnsupportedCriticalExtension();
}
}
|
这里是checkServerTrusted中对证书链的处理
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| @Override
public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
chain = Arrays.copyOf(chain, chain.length);
X509Certificate[] newChain = new X509Certificate[chain.length];
for (int i = 0; i < chain.length; i++) {
newChain[i] = new EternalCertificate(chain[i]);
}
chain = newChain;
this.innerTrustManager.checkServerTrusted(chain, authType);
}
|
这里innerTrustManager是默认的trustManager.可以这样拿到,传给自定义的TrustManager,以便调用原本的相关方法.
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| TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
trustManagerFactory.init((KeyStore) null);
final X509TrustManager defaultTrustManager = (X509TrustManager) trustManagerFactory.getTrustManagers()[0];
|
到这里问题差不多解决了.但是为安全着想,以及影响范围最小化的原则,我们最好是针对本公司的证书做这样的忽略.这里涉及到证书结构.顺便学习了一波.
Android用的是X509证书格式.这里是一个证书示例.
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| Certificate:
Data:
Version: 3 (0x2)
Serial Number:
05:6f:a7:c7:98:b4:9a:cd:68:a9:39:37:7b:bd:66:73
Signature Algorithm: sha256WithRSAEncryption
Issuer: C=US, O=DigiCert Inc, CN=DigiCert SHA2 Secure Server CA
Validity
Not Before: Dec 5 00:00:00 2017 GMT
Not After : Feb 5 12:00:00 2019 GMT
Subject: C=CN, L=Changsha, O=xxxxxx xxxx xxxxx xxxxx Co., Ltd, OU=IT, CN=*.xxx.com
Subject Public Key Info:
Public Key Algorithm: rsaEncryption
Public-Key: (2048 bit)
Modulus:
00:c0:31:45:83:9f:01:81:e8:b1:9f:75:ed:9b:45:
04:05:3b:6e:14:f1:68:35:b2:80:d1:bc:d3:53:40:
ac:b4:b6:fe:8d:f2:bf:c1:58:f8:b6:a8:54:b8:ae:
bf:01:b8:77:10:3a:7b:f8:33:90:67:01:70:d2:cc:
80:91:c0:02:7c:b0:87:8d:8d:c0:30:3c:e2:44:69:
ef:8a:07:80:b0:b9:8a:8e:e9:fd:28:08:9b:b5:7f:
ac:60:5d:6e:b2:c9:c9:b4:fc:12:0a:df:1a:5a:0b:
39:8d:5c:7f:f7:7d:16:1a:6a:f3:a7:dd:2c:81:aa:
b8:83:c2:60:11:f6:05:0d:6e:8b:75:36:44:74:a0:
96:fd:86:36:30:58:90:6a:13:48:a7:c9:16:af:72:
58:a5:f1:3c:39:95:93:e4:e4:78:78:f4:68:4a:59:
0c:e4:e2:7d:14:21:8a:91:ea:5d:5b:95:d0:dc:a4:
cb:64:9c:33:98:db:4b:52:5e:fa:0c:3a:f4:45:f6:
98:04:81:ec:45:1e:60:f9:a2:23:6c:84:f7:e2:d0:
bb:12:70:7f:e1:83:f6:9b:f2:6f:9d:53:ce:57:3d:
60:90:db:a6:b7:e0:15:bb:7a:7e:b0:53:ad:0a:97:
c2:91:4a:5c:a9:81:9a:ee:ad:17:80:68:a4:50:74:
19:c1
Exponent: 65537 (0x10001)
X509v3 extensions:
X509v3 Authority Key Identifier:
keyid:0F:80:61:1C:82:31:61:D5:2F:28:E7:8D:46:38:B4:2C:E1:C6:D9:E2
X509v3 Subject Key Identifier:
EF:85:1D:4E:E3:57:C2:03:63:BD:70:C0:0F:4D:E5:58:42:60:E8:72
X509v3 Subject Alternative Name:
DNS:*.xxx.com, DNS:*.api.xxx.com, DNS:*.bz.xxx.com, DNS:*.log.xxx.com
X509v3 Key Usage: critical
Digital Signature, Key Encipherment
X509v3 Extended Key Usage:
TLS Web Server Authentication, TLS Web Client Authentication
X509v3 CRL Distribution Points:
Full Name:
URI:http://crl3.digicert.com/ssca-sha2-g6.crl
Full Name:
URI:http://crl4.digicert.com/ssca-sha2-g6.crl
X509v3 Certificate Policies:
Policy: 2.16.840.1.114412.1.1
CPS: https://www.digicert.com/CPS
Policy: 2.23.140.1.2.2
Authority Information Access:
OCSP - URI:http://ocsp.digicert.com
CA Issuers - URI:http://cacerts.digicert.com/DigiCertSHA2SecureServerCA.crt
X509v3 Basic Constraints: critical
CA:FALSE
Signature Algorithm: sha256WithRSAEncryption
81:f9:b8:e6:ae:ee:e2:89:12:8d:d4:d0:6c:c0:04:45:f2:9e:
5b:38:67:ea:12:f8:0f:50:2f:27:77:ab:45:79:31:4c:16:cc:
2f:58:9b:7c:11:43:a7:88:c3:6e:ce:b0:89:fb:e4:c1:ac:8b:
d3:ae:d0:ee:3c:cb:33:54:03:0c:aa:4f:6a:23:02:58:e5:ed:
55:16:1a:d3:a8:95:1e:0a:6d:f9:49:25:53:02:9b:19:fb:22:
e2:b1:8f:1c:22:ac:08:76:3f:fd:4f:d4:7e:57:17:93:2c:80:
b0:0c:ff:d5:c9:bb:b2:bb:fc:95:61:2c:e9:94:f9:e2:e9:45:
7c:02:64:e1:52:a3:8b:fa:48:8c:9b:5a:bd:76:f3:91:b0:3a:
d9:27:6c:b6:35:38:ac:88:bf:48:9e:19:e3:17:59:7e:00:d9:
e6:2f:bc:08:0a:c5:37:4d:ed:4d:14:78:d1:94:c3:40:6a:95:
96:91:f6:38:2e:e4:63:f7:fd:f6:fb:25:a5:1c:b0:5a:29:e3:
dd:d7:68:97:2a:58:26:fb:a1:18:e7:e3:80:94:6b:1f:b0:65:
a6:65:1d:79:8f:d7:1a:3a:7b:7a:3c:db:a6:60:a9:99:de:57:
f5:7a:bc:4d:05:e3:64:e2:a9:6f:a1:64:09:6f:a5:51:62:a2:
da:b3:6d:f3
|
关于里面的字段解释,可以对照这个来看
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| 1. 证书版本号(Version)
版本号指明X.509证书的格式版本，现在的值可以为:
1) 0: v1
2) 1: v2
3) 2: v3
也为将来的版本进行了预定义
2. 证书序列号(Serial Number)
序列号指定由CA分配给证书的唯一的"数字型标识符"。当证书被取消时，实际上是将此证书的序列号放入由CA签发的CRL中，
这也是序列号唯一的原因。
3. 签名算法标识符(Signature Algorithm)
签名算法标识用来指定由CA签发证书时所使用的"签名算法"。算法标识符用来指定CA签发证书时所使用的:
1) 公开密钥算法
2) hash算法
example: sha256WithRSAEncryption
须向国际知名标准组织(如ISO)注册
4. 签发机构名(Issuer)
此域用来标识签发证书的CA的X.500 DN(DN-Distinguished Name)名字。包括:
1) 国家(C)
2) 省市(ST)
3) 地区(L)
4) 组织机构(O)
5) 单位部门(OU)
6) 通用名(CN)
7) 邮箱地址
5. 有效期(Validity)
指定证书的有效期，包括:
1) 证书开始生效的日期时间
2) 证书失效的日期和时间
每次使用证书时，需要检查证书是否在有效期内。
6. 证书用户名(Subject)
指定证书持有者的X.500唯一名字。包括:
1) 国家(C)
2) 省市(ST)
3) 地区(L)
4) 组织机构(O)
5) 单位部门(OU)
6) 通用名(CN)
7) 邮箱地址
7. 证书持有者公开密钥信息(Subject Public Key Info)
证书持有者公开密钥信息域包含两个重要信息:
1) 证书持有者的公开密钥的值
2) 公开密钥使用的算法标识符。此标识符包含公开密钥算法和hash算法。
8. 扩展项(extension)
X.509 V3证书是在v2的基础上一标准形式或普通形式增加了扩展项，以使证书能够附带额外信息。标准扩展是指
由X.509 V3版本定义的对V2版本增加的具有广泛应用前景的扩展项，任何人都可以向一些权威机构，如ISO，来
注册一些其他扩展，如果这些扩展项应用广泛，也许以后会成为标准扩展项。
9. 签发者唯一标识符(Issuer Unique Identifier)
签发者唯一标识符在第2版加入证书定义中。此域用在当同一个X.500名字用于多个认证机构时，用一比特字符串
来唯一标识签发者的X.500名字。可选。
10. 证书持有者唯一标识符(Subject Unique Identifier)
持有证书者唯一标识符在第2版的标准中加入X.509证书定义。此域用在当同一个X.500名字用于多个证书持有者时，
用一比特字符串来唯一标识证书持有者的X.500名字。可选。
11. 签名算法(Signature Algorithm)
证书签发机构对证书上述内容的签名算法
example: sha256WithRSAEncryption
12. 签名值(Issuer's Signature)
证书签发机构对证书上述内容的签名值
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所以在X509Certificate封装过程中如何识别,就根据实际情况自行决定了.