Microsoft finally bans SHA-1 certificates in Internet Explorer and Edge

All SHA-1 certificates that chain back to publicly trusted certificate authorities will be blocked, but enterprise and self-signed certificates won't be affected.

The Tuesday updates for Internet Explorer and Microsoft Edge force those browsers to flag SSL/TLS certificates signed with the aging SHA-1 hashing function as insecure. The move follows similar actions by Google Chrome and Mozilla Firefox earlier this year.

Browser vendors and certificate authorities have been engaged in a coordinated effort to phase out the use of SHA-1 certificates on the web for the past few years, because the hashing function no longer provides sufficient security against spoofing.

SHA-1 (Secure Hash Algorithm 1) dates back to 1995 and has been known to be vulnerable to theoretical attacks since 2005. The U.S. National Institute of Standards and Technology has banned the use of SHA-1 by U.S. federal agencies since 2010, and digital certificate authorities have not been allowed to issue SHA-1-signed certificates since Jan. 1, 2016, although some exemptions have been made -- for example, for outdated payment terminals.

A hash function like SHA-1 is used to calculate an alphanumeric string that serves as the cryptographic representation of a file or a piece of data. This is called a digest and can serve as a digital signature. It is supposed to be unique and non-reversible.

In February, researchers from Google and CWI (Centrum Wiskunde & Informatica, a math research center in The Netherlands) have proved the first practical collision attack against SHA-1, producing two PDF files with the same SHA-1 digest. This proved without a doubt that the aging hashing function is effectively broken and should not be used for sensitive applications.

Browser vendors have planned since 2015 to flag SHA-1 certificates as insecure and block them. Google Chrome and Mozilla Firefox used a staged approach: Since early 2016 the browsers blocked SHA-1 certificates issued after Jan. 1, 2016 and since January this year they started blocking all existing SHA-1 certificates, including old ones that have long validity periods.

Chrome version 56, released in January, started blocking all SHA-1 certificates that chain back to publicly trusted certificate authorities. In version 57 it also started blocking SHA-1 certificates that chain back to a local root CA. However, it provides a policy mechanism for organizations to disable this restriction. That's because enterprises might run their own internal certificate infrastructures that rely on self-generated SHA-1 root certificates and cannot easily replace them due to legacy systems that don't support newer hashing functions like SHA-2.

The ban on SHA-1 certificates introduced Tuesday in IE and Edge will only impact certificates that chain to a root certificate in the Microsoft Trusted Root Program, Microsoft said in a security advisory.

Enterprise and self-signed SHA-1 certificates will not be affected for now, but Microsoft's long term plan is to phase out SHA-1 from all usages in Windows, including the function's use for verifying the integrity of downloaded files.

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Lucian Constantin

IDG News Service
Show Comments

Brand Post

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Luke Hill

MSI GT75 TITAN

I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Laura Johnston

MSI GS65 Stealth Thin

If you can afford the price tag, it is well worth the money. It out performs any other laptop I have tried for gaming, and the transportable design and incredible display also make it ideal for work.

Andrew Teoh

Brother MFC-L9570CDW Multifunction Printer

Touch screen visibility and operation was great and easy to navigate. Each menu and sub-menu was in an understandable order and category

Louise Coady

Brother MFC-L9570CDW Multifunction Printer

The printer was convenient, produced clear and vibrant images and was very easy to use

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Featured Content

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?