I suspect the vast majority of Authy backups use passwords trivially susceptible to brute-force attacks despite only 1000 (!!!) iterations of PBKDF2. If Authy wanted to do things right, it would generate local encryption keys instead of asking normies for file encryption passphrases.
argon2/scrypt with significantly larger costs sound like the right fix. Asymmetric crypto can make backing up still cheap, who cares if restoring takes 30 seconds.
That would be a great improvement for technical users. But also consider that the target for Authy is the average mobile user. I’m not unconvinced that the typical backup password looks like S3cr3tP@s$w0rd, which no amount of key stretching will fix.
Yes. What I meant was that Authy does encrypted backups. You can criticize how it's implemented, but it's there, it works, and your 2FA secrets aren't just sitting in the cloud.
I think I'll refrain from posting on topics about Google — clearly there is a huge pro-Google sentiment among HN readers and anything detracting from that gets instantly downvoted.