Certificates with SHA-1 and SunCertPathBuilderException

As SHA-1 is heading to deprecation as hashing algoritm for certificate signatures, unpleasant effects start to appear.

Our partners we need to communicate with over HTTPS have brand new certificate signed by GoDaddy Certificate Authority. Accessing their https secured site via browser does not show anything alarming.

But accessing REST endpoint hosted on same site using java HttpUrlConnection blows up with javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

What is going on?

Every internet browser comes with quite a big set of preinstalled Certificate Authorities (CA) trusted certificates, because your browser's vendors trusts them. And because they are CAs and they are trusted, then every certificate that is signed by them is trusted too.

Same story with JVM. There is truststore file inside every JVM named cacerts. In Oracle jdk1.7.0_67 there is 87 Certificate Authorities in it as they are trused by Oracle. GoDady is there too, so why that SunCertPathBuilderException? Let's examine it more closely.

Every JVM is also shipped with command line tool named keytool. Using it you can list and also modify any keystore in jks format such as cacerts Executing... (default password is changeit)

 
keytool -list -v -keystore ${JAVA_HOME}/jre/lib/security/cacerts -storepass changeit | grep -A 14 godaddy

...will print following...

Alias name: godaddyclass2ca
Creation date: 20-Jan-2005
Entry type: trustedCertEntry

Owner: OU=Go Daddy Class 2 Certification Authority, O="The Go Daddy Group, Inc.", C=US
Issuer: OU=Go Daddy Class 2 Certification Authority, O="The Go Daddy Group, Inc.", C=US
Serial number: 0
Valid from: Tue Jun 29 18:06:20 BST 2004 until: Thu Jun 29 18:06:20 BST 2034
Certificate fingerprints:
  MD5:  91:DE:06:25:AB:DA:FD:32:17:0C:BB:25:17:2A:84:67
  SHA1: 27:96:BA:E6:3F:18:01:E2:77:26:1B:A0:D7:77:70:02:8F:20:EE:E4
  SHA256: C3:84:6B:F2:4B:9E:93:CA:64:27:4C:0E:C6:7C:1E:CC:5E:02:4F:FC:AC:D2:D7:40:19:35:0E:81:FE:54:6A:E4
  Signature algorithm name: SHA1withRSA
  Version: 3

Now cmparing to certificate from HTTPS website... GoDaddyG2 cerificate

There is obvious mismatch. Apart from different certificate name, validity date range also notice that Signature Algorithm is "SHA-256 with RSA". GoDaddy's certificate in JVM is different from the one in use on website, therefore SunCertPathBuilderException.

To fix this, we need to add right (G2) GoDaddy's certificate into JVM cacert keystore. Visiting GoDaddy's certificate repository obvious candidate "GoDaddy Class 2 Certification Authority Root Certificate - G2" can be found there.

wget https://certs.godaddy.com/repository/gdroot-g2.crt
keytool -printcert -file gdroot-g2.crt

Will give us something we saw in website certificate...

Owner: CN=Go Daddy Root Certificate Authority - G2, O="GoDaddy.com, Inc.", L=Scottsdale, ST=Arizona, C=US
Issuer: CN=Go Daddy Root Certificate Authority - G2, O="GoDaddy.com, Inc.", L=Scottsdale, ST=Arizona, C=US
Serial number: 0
Valid from: Mon Aug 31 20:00:00 EDT 2009 until: Thu Dec 31 18:59:59 EST 2037
Certificate fingerprints:
  MD5:  80:3A:BC:22:C1:E6:FB:8D:9B:3B:27:4A:32:1B:9A:01
  SHA1: 47:BE:AB:C9:22:EA:E8:0E:78:78:34:62:A7:9F:45:C2:54:FD:E6:8B
  SHA256: 45:14:0B:32:47:EB:9C:C8:C5:B4:F0:D7:B5:30:91:F7:32:92:08:9E:6E:5A:63:E2:74:9D:D3:AC:A9:19:8E:DA
  Signature algorithm name: SHA256withRSA
  Version: 3

Now just import gdroot-g2.crt into JVM cacerts truststore

sudo keytool -import -alias godaddyg2ca -file gdroot-g2.cer -keystore ${JAVA_HOME}/jre/lib/security/cacerts -storepass changeit

Owner: CN=Go Daddy Root Certificate Authority - G2, O="GoDaddy.com, Inc.", L=Scottsdale, ST=Arizona, C=US
Issuer: CN=Go Daddy Root Certificate Authority - G2, O="GoDaddy.com, Inc.", L=Scottsdale, ST=Arizona, C=US
Serial number: 0
Valid from: Tue Sep 01 01:00:00 BST 2009 until: Thu Dec 31 23:59:59 GMT 2037
Certificate fingerprints:
  MD5:  80:3A:BC:22:C1:E6:FB:8D:9B:3B:27:4A:32:1B:9A:01
  SHA1: 47:BE:AB:C9:22:EA:E8:0E:78:78:34:62:A7:9F:45:C2:54:FD:E6:8B
  SHA256: 45:14:0B:32:47:EB:9C:C8:C5:B4:F0:D7:B5:30:91:F7:32:92:08:9E:6E:5A:63:E2:74:9D:D3:AC:A9:19:8E:DA
  Signature algorithm name: SHA256withRSA
  Version: 3

Extensions: 

#1: ObjectId: 2.5.29.19 Criticality=true
BasicConstraints:[
  CA:true
  PathLen:2147483647
]

#2: ObjectId: 2.5.29.15 Criticality=true
KeyUsage [
  Key_CertSign
  Crl_Sign
]

#3: ObjectId: 2.5.29.14 Criticality=false
SubjectKeyIdentifier [
KeyIdentifier [
0000: 3A 9A 85 07 10 67 28 B6   EF F6 BD 05 41 6E 20 C1  :....g(.....An .
0010: 94 DA 0F DE                                        ....
]
]

Trust this certificate? [no]:  yes
Certificate was added to keystore

Problem solved and REST call should succeed from now using this JVM

For completeness sake, if you want to get rid of it, execute

keytool -delete -alias godaddyg2ca -keystore ${JAVA_HOME}/jre/lib/security/cacerts

What in case you are not allowed to modify JVM cacerts truststore?

Then make a copy of it, import gdroot-g2.cer into it and use this custom truststore instead of default JVM truststore using -Djavax.net.ssl.trustStore=/path/to/custom_cacerts -Djavax.net.ssl.trustStorePassword=changeit java parameters

What in case you need multiple keystores or something similarily complex?

Such scenarios cannot be solved simply by using JVM switches and parameters anymore and you have to roll your own X509TrustManager implementation. Then you need to plug it into your http client connection setup - (HttpsUrlConnection SSLSocketFactory) (Apache HttpClient 3 SecureProtocolSocketFactory) (Apache HttpClient 4 SSLConnectionSocketFactory ) (Jersey SslConfigurator)