It’s About Time to Move onto SHA-2

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If you aren’t using a SHA-2 SSL certificate, you are in trouble

It is always advisable to stay well-informed about the latest and safest cryptographic protocols in the Internet security market, as these are specially devised to protect your data and applications from modern-day cyber-attacks.

Secure Hash Algorithm (SHA)

SHA is a family of several cryptographic hash functions, namely SHA-0, SHA-1, SHA-2 and SHA-3. It was published by the National Institute of Security and Technology (NIST). Certification Authorities (CAs) use SHA hash functions while signing digital certificates and Certificate Revocation Lists (CRLs). The concept was initialized with the purpose to generate unique hash values from the files. In the case of SSL certificates, the rationale of a hashing algorithm is to reduce reasonably a message to use it with a digital signature algorithm.

As an effective cryptographic solution, security experts make sure the hash functions are advanced enough to be in-sync with computers’ calculation capacity to avoid vulnerabilities. This is precisely the reason why advanced versions are introduced to ensure effective safety.

Why all the rush to transition from SHA-1 to SHA-2?

The Year 2011 marked the onset of SHA-1 deprecation, when an industry group of leading web browsers and Certificate Authorities (CAs) at the CA/Browser Forum worked together to establish basic security requirements for SSL certificates and published their ‘Baseline Requirements for SSL’. These requirements recommended all the CAs to move on to SHA-2 from SHA-1.

So, based on the SHA-1 weaknesses found in SHA-1, in terms of security, here is why all users should reconsider their conventional choice and select SHA-2 when it comes to choosing a hash algorithm.

Switch to SHA-2 from SHA-1


Ever since the late 1990s, SHA-1 has been every CA’s popular choice for signing digital certificates. So much so, that by 2013, SHA-1 certificates accounted for almost 98% of the total number of certificates being issued. However, of late, the cryptographically advanced cyber-attacks on SHA-1 has led security experts to believe that the industry cannot afford anymore to continue using SHA-1, at the stake of users’ online security.

A recent research on cyber-attacks has revealed a picture that depicts SHA-1 to have become a regular target for attackers. Even if there has never been a successful complete collision (attack) in case of SHA-1, the evolution of our computers’ calculation capacities will soon make it possible. However, unlike SHA-1, SHA-2 is totally collision-resistant.

Now, a hashing algorithm is considered to be secure only if a unique output is produced for any given input which works one way and cannot be reversed. But, in 2005, SHA-1 was found to be the victim of ‘collision’ attacks. These are the kind of attacks where multiple inputs can produce the same output, which makes SHA-1 incapable of producing a cryptographically secure message digest. After that attack, SHA-1 was quite often found to be vulnerable towards many different attacks.

1995: SHA-1 published
2005: SHA-1 collision attack published in 2^69 calls
2005: NIST recommendation for movement away from SHA-1
2012: Identical-prefix collision 2^61 calls presented
2012: Chosen-prefix collision 2^77.1 calls presented

Microsoft© SHA-1 Deprecation Policy

By November 2013, Microsoft© announced a new policy about deprecating the use of SHA-1 algorithm in SSL certificates for all the certificate authorities (CAs). As per the policy, Microsoft© shall allow CAs to continue certificate issuance using SHA-1 only till January 1 2016, after which it will permit the usage of only SHA-2, which is considered to be a safer option.

Following the vulnerabilities found in SHA-1, even the US NIST Guidance has advised that SHA-1 should not be trusted after January 1 2017 for achieving a higher level of assured communications over the US Federal Bridge PKI.

With the fundamental goal of protecting the integrity of the Windows platform and Windows customers, Microsoft© released a deprecation policy comprising of deadlines that gives fair amount of time for such massive transition.

Key Points

  • Jan 1 2016 – All the CAs should stop issuing SHA-1
  • Jan 1 2017 – MS Windows will not accept SHA-1 SSL certificates
  • Jan 1 2017 – SHA-1 code signing certificates without time-stamp won’t be accepted after that.

Google Disapproves SHA-1

Google© announced their SHA-1 deprecation policy in September 2014. As per the new policy, by 2017 Google Chrome will stop accepting SHA-1 certificates in a phased way.

The SHA-1 deprecation on Google’s Chromium user interface is projected to evolve in the following pattern:

  • In Chrome 39, which is all set to release in November 2014, any SHA-1 SSL certificate with an expiration date on or after January 1 2017 will trigger ‘minor’ errors on the address bar.
  • In Chrome 40, which is expected to be released in post-holiday season, the web pages that rely on SHA-1 SSL certificate with expiration date between June 1 2016 to December 31 2016, will generate minor errors on the address bar and the ones that are expiring after January 1 2017 shall be treated as ‘neutral, lacking security’.
  • In Chrome 41, which is to be released in the second quarter of 2015, the SHA-1 certificates that are expiring between January 1 2016 and December 31 2016 will be treated with minor errors. And in the case of certificates expiring on or after January 1 2017, affirmative warnings depicting ‘insecure’ status will be generated.


SHA-2 is a set of hashing algorithms, which features a high level of security as compared to its older version, SHA-1. It is developed through the National Institute of Standards and Technology (NIST) and National Security Agency (NSA). The SHA-2 set of algorithms is patented in US 6829355 and the United States has released the patent under royalty-free license. Currently, the SHA-2 family consists of the following algorithms:

SHA-256 & SHA-512 – These the novel hash functions, which are computed with 32-bit and 64-bit words respectively. Their structures are almost identical in spite of using different shift amounts and additive constants. Their structures differ only in the number of rounds.

SHA-224 & SHA- 384 – Commonly referred to as the truncated versions of the above mentioned algorithms. Both these are computed with different initial values.

SHA-512/224 & SHA 512/256 – These are the truncated versions of SHA-512.

Servers Compatible with SHA-2

The servers in the list below are compatible with SHA-2 algorithm:

  • Apache server (tested with Apache 2.0.63 and Open SSL 0.9.7m. It requires OpenSSL 0.9.80+ for complete implementation)
  • Windows Server 2008+
  • Windows Vista
  • Windows Server 2003 with patch 938397
  • Windows Server 2003 or XP client with patch 968730
  • Oracle WebLogic from the version 10.3.1, see bug8422

Browsers Compatible with SHA-2

All browsers mentioned below are compatible with SHA-2:

  • Internet Explorer under Seven and higher
  • Internet Explorer 7+ under Vista
  • Internet Explorer 7+ under Windows XP SP3
  • Firefox 1.5+
  • Netscape 7.1+
  • Mozilla 1.4+
  • Safari from Mac OS X 10.5
  • Opera 9.0+
  • Mozilla products based on NSS 3.8+ (since April 2003)
  • Products based on OpenSSL 0.9.8o+
  • Java 1.4.2+ based products
  • Chrome under Windows Vista and higher
  • Chrome under Mac from Mac OS X 10.5
  • Chrome under Linux

SHA-2 Applications

Here are just a few applications for SHA-2:

  1. This algorithm is widely implemented in popular security applications and protocols like SSL, TLS, IPSec, S/MIME, SSH, PGP etc.
  2. There are many Cryptocurrencies that rely on SHA-2 as a part of their proof-of-work scheme.
  3. Just like SHA-1, SHA-2 is also needed by law, to be used in many US government applications.
  4. SHA-2 rightfully performs the most basic SHA function of effectively verifying the procedure of message authentication along with password verification as well.
  5. Authenticating Debian, GNU/ Linux & DKIM Message signing standard are performed using SHA-2.

How to Migrate for New SHA-2 Algorithm?

Apparently the SHA-2 Revolution has taken Internet security by storm. Especially after having SHA-1 deprecation policies coming from leading web browsers. So, this brings us to the juncture where it has become almost necessary to replace SHA-1 with its secure predecessor, SHA-2 algorithm. Here is the procedure for all the users intending to migrate or concerned about the migration from SHA-1 to SHA-2 should do.

First of all, the users are requested to check their websites and confirming which algorithm is being used by the SSL certificate securing the website. Please click here to check your website for SHA-1 encryption. After getting the results, if you find your website to be relying on an SHA-1 SSL certificate, then you are advised to migrate it to SHA-2 SSL certificate. Here is a stepwise procedure for our users to follow, steps of which can be performed even without any expertise:

Existing Customers

If you are an existing customer and have already purchased an SSL certificate but it has SHA-1 algorithm, then you can upgrade it by following these steps-

Step 1 – Go to the ‘My Order’ or ‘Order Listing’ page and click on the ‘Order ID’ option to get to the order details page. On the order detail page, click on the re-issue button located on the bottom side on the same page.

Step 2 – After that, you shall receive an e-mail from ComodoSSLStore© which contains a centralapi link.

Step 3 – You shall be soon re-directed to the panel of ‘Certificate Reissue’

Step 4 – Now enter your SSL certificate’s CSR with SHA-2. After that, scroll the drop down menu given for ‘Algorithm’ and carefully select SHA-2.

Step 5 – Above step completes the procedure of migration for existing customers. Your re-issued certificate shall be sent to you via e-mail. You can download and install this certificate by following the routine procedures.

New Customer

However, if you are a new customer and wish to purchase a SHA-2 SSL certificate, please follow all the steps mentioned below:

Step 1 – First of all, the customers need to generate a new CSR by choosing the SHA-2 algorithm..

Step 2 – Next, click on the ‘Generate Certificate’ button to proceed to the order.

Step 3 – Next, you would be directed to the panel of ‘Certificate Issuance’ process panel where you need to enter the CSR you generated in the first step.

NOTE: Keep in mind to select SHA-2 algorithm while placing the order.

Step 4– Certificate Authorities shall soon send you an email with your new SSL Certificate.