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> Firefox used to have great sync security. I ran my own sync server for years, and was very happy with it. But when they revised the protocol they destroyed it

> Firefox used to have great sync security. I ran my own sync server for years, and was very happy with it. But when they revised the protocol they destroyed its security. Firefox Sync is unacceptable for password storage Oh, I'm unknowledgeable about this. Could you expand a bit on why it is insecure or what they did to it to make it insecure etc. Even just links would be enough.

zeveb 10y ago
> Could you expand a bit on why it is insecure Sure thing. I'm referring to https://blog.mozilla.org/warner/2014/05/23/the-new-sync-protocol/ https://blog.mozilla.org/warner/2014/05/23/the-new-sync-prot... for details of the new protocol. Your synced data is encrypted with a 256-bit key kB. So far, so good. The problem is that kB is encrypted using a function of your Firefox Account password: if someone can guess or intercept your password, then he can decrypt kB and then decrypt any synced data. So, how hard is it to guess or intercept your password? Well, if you can remember your Firefox Account password, it's almost certainly guessable given enough machines. Human-memorable passwords almost never have high enough entropy to survive sustained attack. But maybe you store a truly high-entropy password (e.g. i2FH9E0G6PoCZm41C0pIJdLg1uOcGaA0GfhxKUtSQ) elsewhere, and enter it into the Firefox Account sign-in screen. Now no-one can guess your password, and that means that you're secure, right? Wrong: the Firefox Account sign-in screen (https://accounts.firefox.com/signin https://accounts.firefox.com/signin) is served from Mozilla's servers, which means that any time you visit it they may choose to serve JavaScript which transmits your password to them (normally they would perform all operations on your password locally). 'But I trust Mozilla to write Firefox!' you might argue. Sure, but it's (theoretically) possible to verify the Firefox source and binaries once; it's (theoretically) possible to verify that the source or binary they serve you is the same as that they serve to the rest of the world. With code delivered online, an attack can be targeted just once, at a single person: if you're not logging each and every login form's source code then you're exposed. A malicious (or compelled) Mozilla employee (or employees) could target a user; moreover, any government Mozilla is subject to could compel it to target a user. Their old system performed all operations locally, always; it never downloaded and then executed source. It was secure. Their new system is not much better than, 'trust us.'

zeveb 10y ago

> Could you expand a bit on why it is insecure Sure thing. I'm referring to https://blog.mozilla.org/warner/2014/05/23/the-new-sync-protocol/ https://blog.mozilla.org/warner/2014/05/23/the-new-sync-prot... for details of the new protocol. Your synced data is encrypted with a 256-bit key kB. So far, so good. The problem is that kB is encrypted using a function of your Firefox Account password: if someone can guess or intercept your password, then he can decrypt kB and then decrypt any synced data. So, how hard is it to guess or intercept your password? Well, if you can remember your Firefox Account password, it's almost certainly guessable given enough machines. Human-memorable passwords almost never have high enough entropy to survive sustained attack. But maybe you store a truly high-entropy password (e.g. i2FH9E0G6PoCZm41C0pIJdLg1uOcGaA0GfhxKUtSQ) elsewhere, and enter it into the Firefox Account sign-in screen. Now no-one can guess your password, and that means that you're secure, right? Wrong: the Firefox Account sign-in screen (https://accounts.firefox.com/signin https://accounts.firefox.com/signin) is served from Mozilla's servers, which means that any time you visit it they may choose to serve JavaScript which transmits your password to them (normally they would perform all operations on your password locally). 'But I trust Mozilla to write Firefox!' you might argue. Sure, but it's (theoretically) possible to verify the Firefox source and binaries once; it's (theoretically) possible to verify that the source or binary they serve you is the same as that they serve to the rest of the world. With code delivered online, an attack can be targeted just once, at a single person: if you're not logging each and every login form's source code then you're exposed. A malicious (or compelled) Mozilla employee (or employees) could target a user; moreover, any government Mozilla is subject to could compel it to target a user. Their old system performed all operations locally, always; it never downloaded and then executed source. It was secure. Their new system is not much better than, 'trust us.'