Old devices that are still fully operational often land in the hands of people in developing economies as they approach the end of their lives. Smartphones might only be 2–4 years old, but their manufacturers have long since finished patching their software. One of the older algorithms used for encrypting web sites has become more realistically crackable in recent years. sha1 is now being marked as insecure and even completely blocked by some major browsers as of Jan. 1st, potentially leaving up to 37 million older devices without access to encrypted sites. Should weak security be allowed so as not to alienate those without the resources to upgrade, or should we at all cost disallow insecure channels of communication by killing SHA1?
The lock that precedes the URL in your favorite browser on secure sites signifies that you are theoretically loading a page from the real server as well as that all data transmitted between your browser and that server is jumbled so that passive onlookers along the pipe cannot decipher its content. Multiple algorithms provide this encryption, and one of the older ones has been deemed to be relatively weak for use in 2016. The CA/Browser Forum, the industry working group that manages web encryption standards, has officially disallowed SHA1 as of the first of the year. There is no evidence that anyone has accomplished a collision (the feared hack). Moreover, even if someone creates a collision, the hacker would still require access to the domain’s DNS records to imitate the legitimate site. All that to say, SHA1 is indeed weak, but still, potentially has some life in it. Maybe it should not be killed until researchers surface more evidence of it being crackable.
It is especially notable that it is often in these developing countries where extreme censorship by repressive governments is most commonplace. If SHA1 is deprecated altogether by major websites and browsers, citizens who cannot afford more modern technology will be completely shut off from the resources that the open Internet provides. However, if SHA1 becomes crackable in the very near future as experts suggest, communication that citizens believe to be secure might be passively snooped upon by government agencies.
In conclusion, for those with means, upgrade. Upgrade both your hardware and your software. Support manufacturers who patch their devices for years after production. For those who cannot afford to upgrade their devices, however, it seems that the best solution would be for websites to offer encrypted connections primarily via the more modern SHA2, but still, provide a fallback without killing SHA1 completely only for browsers that are not capable of using the newer algorithm. This is what both Facebook’s and CloudFlare’s (speed and security proxy for millions of websites including this one) properties are doing. There is a risk, though, that SHA1 will be cracked very soon and that unsuspecting and potentially uneducated folks using these old devices will unknowingly offer highly sensitive and personal information to corrupt governments and bad actors.