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I was quickly wondering, why don't ISPs offer encryption for the traffic from the customer's router to the ISP-server?

Until now, if you want to protect against e.g a MitM-attack you solely rely on TLS, a VPN, or an encrypted proxy-network like Tor. Encryption from the ISP would offer a big extra layer of security.

How could it work?

For example, the ISP sends a new generated key to the routers every day. This key is encrypted using an algorithm which does calculations on vectors like time, and/or a pattern (similar to product keys). The algorithm to decrypt this key is hard-coded in the routers. Now, the routers have a new key each day, and that key can be used to encrypt the connection from router -> ISP.

Of course to hide info for your ISP, you'd still have to use a VPN or Tor. Yet this would be an extra layer of security.

Why aren't ISPs doing this?

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1  
Someone correct me if I'm wrong but my understanding is that the DOCSIS standard, which is used to connect end-user cable modems to ISPs, does provide support for encryption. – tlng05 Feb 15 at 17:33
    
@tlng05 Does it mean because it's supported, it's also used? And why are MiTM attacks (before packet reached ISP) possible then? – O'Niel Feb 15 at 17:40
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What's your question? How to theoretically design encryption for router-to-ISP links? What would be be the benefit? The entire stream isn't being encrypted, so the user would have to encrypt, then the ISP encrypts over top, causing huge costs. – schroeder Feb 15 at 17:50
    
Why would the ISPs want to? what is their incentive? having the NSA on their backs to remove the encryption? – user2813274 Feb 16 at 2:39
up vote 9 down vote accepted

For ISPs to do encryption across all lines they'd have to make sure that all devices on their backbone can support encryption. Many of these devices are old. As the OPM leaks taught us, many organizations don't upgrade equipment that can support what we consider now to be "secure communications".

At the root of it though is that it wouldn't make a difference in your communications. Even if your communications to the ISP is encrypted, going out past them to a server would then be dumped back out into the Internet in plaintext. No one's end point for data is the ISP. Protecting this portion of the communication is redundant because anyone who wants to secure their entire communication path would use a VPN/TLS/HTTPS anyway.

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+1, yet still having a few questions before accepting. 1) Can't encryption be an option for modern hardware-routers? Like you sometimes also need to update software for accessing new features. This'd cause a complex infrastructure (checking who uses encryption) at the ISPs hand. But that can be fixed. 2) The data after ISP indeed would be plaintext, however, at least the connection to the ISP would be encrypted; shouldn't we try to strife to encryption for everything and every single channel? – O'Niel Feb 15 at 20:10
    
@O'Niel if you made the encryption optional, then downgrade attacks would be very simple :) You would just listen for the handshake between the device/router/etc. and ISP and just tell it you support no encryption. – iismathwizard Feb 15 at 22:30
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@O'Niel 1) Encryption can be an option for modern hardware, but a lot of this infrastructure was put down decades ago. Some software might not even be upgradable and new hardware might be required. This becomes a complex problem quickly. 2) Encryption everywhere on every channel is tedious, and doesn't solve any problems. A traceroute to google shows me that it takes 4 hops to get to my ISP. The other 10 are outside of what an ISP would encrypt. That's 10 links of plaintext traffic that someone could sniff or MitM. It just doesn't add security to the overall communication. – RoraΖ Feb 16 at 13:06

The ISPs do not offer encryption because they cannot reliably provide such, and even if they could, it is hardy any protection compared to what end-to-end encryption provides.

End to end protection

Take todays HTTPS traffic for example. The "ends" of the encryption is the smallest unit that needs to access data. For a web site, it is the servers web server software, and on the clients end, it is the web browser. In theory, nobody else can tamper or read the data. Not other software installed on your computer, not other peers connected to your local network, not you own ISP, not the servers ISP, or other servers reside in the data centers can read your data.

As you can see, your own ISP to your router is just a small part of the solution.

Many ISPs already offer tunneling protection and authentication already

In theory, it should be possible someone to access your telephone lines or intercept your 3G/4G or even 2G GSM signals and become a man in the middle. However, some ISPs provide tunnelling features such as PPTP. For 2G/3G/4G, this page has great information about authentication methods provided by those technologies.

Practical issues

I think @Roraz's answer explains it a lot better.

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Alot of standards have the encryption in design, but no ISP implementation has it implemented, why? The answer is too simple : when feds need to illegally hack you without a warrant, they has to be disguised, or you will be able to prosecute them or,at least, do a whistleblow. They are forcing unsafe/unecrypted ISP environments by not-providing permissive dosc for ISP's, etc, if the ISP does some security precautions.

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