Tuesday, May 13, 2014

SSL Certificates - Time to Upgrade to SHA-2

When you go to get a new SSL certificate for your web applications, you should be aware that:
  • As of January 1, 2016, Microsoft will no longer allow certificate authorities in the Microsoft Root Certificate Program to issue certificates for SSL or code signing that use the SHA-1 hashing algorithm. SHA-2 is the preferred method now.
  • Many servers are susceptible to the Heartbldeed OpenSSL Vulnerability and if yours is one of them, then you should fix that.

Benefits of using SHA-2

SHA-2 addresses some weaknesses in the SHA-1 hashing algorithm.

SHA-1 is not considered to be unsafe at this time; however, the weaknesses that have been identified make the algorithm vulnerable to possible exploitation over the coming years.

Disadvantages of SHA-2

One of the drawbacks with SHA-2 is that there are some older applications and operating systems that do not support it. Compatibility problems are the main reason why SHA-2 algorithms have not been adopted more rapidly.

Unsupported Technologies

  • Windows XP Service Pack 2 or lower
  • Apache Web Server version 1.x or lower
  • Java based servers with Java SDK 1.4.1.x or lower
  • Openssl version 1.0.x or lower (pre April 7, 2013)

Supported Technologies

Windows Operating Systems

  • Windows Vista, 7, 8, 8.1
  • Windows XP SP3
  • The SHA-224 hash is not included.

Windows Servers

  • Windows Server 2008, 2008 R2, 2012, 2012 R2
  • Windows Server 2003 SP1 and SP2 with Hotfix KB 938397
  • The SHA-224 hash is not included.


  • Apache server 2.0.63 with OpenSSL0.9.8ο+


  • Internet Explorer 7+ with Windows XP SP3+
  • Safari with Mac OS X 10.5+
  • Firefox 1.5+
  • Netscape 7.1+
  • Mozilla 1.4+
  • Opera 9.0+
  • Konqueror 3.5.6+
  • Mozilla-based browsers since 3.8+
  • OpenSSL 0.9.8ο+
  • Java 1.4.2+ based products
  • Chrome 26+


In total, more than 98% of all SSL certificates in use on the Web are still using SHA-1 signatures. Netcraft's February 2014 SSL Survey found more than 256,000 of these certificates would otherwise be valid beyond the start of 2017 and, due to the planned deprecation of SHA-1, will need to be replaced before their natural expiry dates.

SHA-256 is the most commonly used signature algorithm from the SHA-2 family, but it is used by only 1.86% of the valid certificates in Netcraft's February 2014 SSL Survey; nonetheless, this share has more than doubled in the space of 4 months, suggesting that some certificate authorities are starting to take the issue seriously. So far in 2014, more than 61% of the new certificates signed with SHA-256 were issued by a single certificate authority, Go Daddy. SHA-512 is the only other SHA-2 family algorithm to be seen used in SSL certificates, albeit deployed on only 4 websites so far.



1 comment:

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