Name: TOR隱藏服務 - Computerphile (TOR Hidden Services - Computerphile)
Uploaded: 2021-01-14T10:46:57.000Z
Duration: 11 min 42 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

We've talked about Onion Routing and TOR, and

now i'd like to address the prickly subject of

hidden services, right? AKA the "dark web".

So Max has done a good video on the Dark Web,

and so you should definitely watch that one first,

so you know what it is. But it's quite a controversial topic,

because a lot of what happens on the Dark Web

is illegal, right? There's no two ways about it, that is true.

Some of it isn't, right, and a lot of what happens on TOR

in general--in fact the majority of what happens on TOR

and that, and above--is perfectly fine, right?

it's just anonymous users browsing the web,

doing regular things but the TOR Hidden Services

are ones that the debate is about because

'well, look, is it worth this bit of encryption?

Is it worth, you know, all the criminality that's on there and so on?'

and in essence, we've got lots of people going into

the network. lots of encrypted layers and things

happening, bouncing around, and then people

coming out of the network to servers, right?

Now the issue, from a security standpoint

Is what happens if There's someone Sniffing?

and They Can Correlate Traffic between the in and The out

Specifically Right then the whole Report the whole Point of Tor Which is Anonymization?

Has been defeated, Right? We already have encryption, so that isn't the point of talk,

that's just how, They do the anonymous communication

so the Dark web. or a hidden service to use the Proper Term, is

in Essence Where This server Moves inside this Cloud right so now We have a hidden service Running Inside this Cloud and

There is no B that's the Idea right so it Makes it very very difficult to find so there is Now a circuit that goes

and at no point has that left the network so there's no traffic correlation that can be done, Right?

All of these are just TOR  sale messages that all look exacly the same.

Now, the way that TOR does this Is very very clever.

Euh, and I Look I will look into a little bit of detail on the protocol that it uses

know who each other are, but we can still have a conversation which Is kind of nifty?

So then, let's start again with Onion routing

So, Onion routing is a protocol that could theoretically be implemented elsewhere.

There are other Mixing networks and things and other anonymization networks

But Hidden Services Is put predominately in the domain of TOR.

And TOR got the most users and the most nodes and it's the biggest and is in the News the most.

Let's Draw a little bit of a Network again, so

I shouldn't Have Drawn These Boxes Like This Because Now it takes me ages

I'm Just going to Drawn with Boxes Because otherwise it's going to take far too long

These are Onion routers, so remember in normal Onion routing

[Circuits] [or] some Hops and then they will Just Talk to the server but A server will be out on the normal Web Doing normal

and won't be Anonymous what Hidden Services do Is

Anonymize This Server so they Allow Both the Server and The Client to talk to each other Despite the fact that

No One Knows who each other is Which Is quite Impressive

[Now] of Course if You then use [that] service Connection to Log in You're going to know you are but You get the idea

The Server Has To lay some Groundwork Down before A client Connects use a hidden Service Right so there's protocols in the Tor

Specification for doing This but [what] the server will do when they come online Is they will pick Three Onion Routers at Random and

Name Them as Introduction Points so let's Pick Them at Random now These are just normal Onion Routers They're very Likely to be Just doing

Normal Routing Tasks Like Circuits Through other Clients Into Servers and Things Some of These might be Exit Nodes

Entry Nodes and so on but As far as I know all Onion Routers Can, also act as

Introduction Points it's not A big Job [I] didn't Require A Huge Amount of Bandwidth the server will Make Connections

to These introduction Points They've Either Full on tour Circuits with Three hops in Between Them the idea being That These introduction Points Know They're

Going to be introducing People to this server

Why it's Already the server is Hiding behind A layer of Anonymity here it will send Them a message to say I'd like you to

It will Create something Called A server Hidden Service Descriptor which I was [write] Down here that will Include the service Public key for

Occasion Purposes But I won't dwell on that Particularly but

Also Crucially the ip Addresses [of] These introduction Points Here Now These are all public Anyway they will Publicly Listed

Now it will Publish This Descriptor to something Called a Distributed hash Table that is to [Say] all [of] the Routers on Tor

will Hold Some in Some Part of the Information [on] all of These hidden Services

And the idea Is that if I try and Look up a hidden Service

The [Roots] Are Responsible for it will Give Me Back the Descriptor by including the Addresses

[Over] The Introduction Points Now the key for this Hash table is the Onion Address

Right so the Onion dress that Everyone Knows about

Is actually derived from the public key [of] this Server and Is in Essence the key but Gets

These ips Out of the Distributed hash table the whole Point of this Is [that] the Onion Address isn't publicized on the Global Tor Network

You Just find it other Ways like on A net

On an Internet or your friend tells you or?

in an Email or something like this the [Waiver] [the] Distributed hash Table Is

Programmed The vast Majority of Nodes Won't know what the description Is for A given Key I?

Only want more Probably or couple so there's an Inherent Security here it doesn't until Recently it's

Also Made it Quite difficult to Work at how Many Hidden services There were so this Is all set up now the server sits There

And Waits for [Internet] [Connections] [Or] People to ask for A, web web file Now

Introduction Points Just sit There Being in Being normal Routed and Waiting here me I want to connect to this Hidden Service and Someone gave

Me the Onion Address so that's Really, what I need so what I do is I?

Request The descriptor off the hash Table and it gives it back that has the Three ip

And i pick one At random right let's Say This Top

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