Part 4, Going dark Flashcards
1
Q
how would law enforcement use the Law Enforcement Access Field (LEAF) if they were investigating alice or bob
A
- Intercept the LEAF and the encrypted message
- Arrange with a judge that their unit key be released by the US treasury and the national institute of standards and technology (NIST)
- Decrypt the first layer of encryption using the family key
- Decrypt the second layer of the LEAF using the unit key revealing bob and alices symmetric key
- Decrypt the message using the symmetric key
2
Q
the
unit key of the clipper chip
was held in key escrow but how exactly was it held
A
this was split in half and split between:
- The US treasury
- The National Institute of Standards and Technology (NIST)
3
Q
the keys this held were:
- An 80 bit unit key - a unique key for each device
- A family key - a generic key, held by government
A
what two keys were held by the
clipper chip
4
Q
this is a claim or statement that you would like your audience to believe
A
what is the
main claim
within an argument
5
Q
what is a
TOR node
A
this is a computer that is currently connected to the TOR network and is able to relay messages and be part of a TOR circuit
6
Q
this used the
skipjack symmetric algorithm
A
what encryption algorith did the
clipper chip
use
7
Q
why did the
clipper chip fail
A
- Weaknesses were found with the hash authentication of the LEAF being that collisions were present
- Later it was found that skipjack itself was not strong as it was cracked just days after the documents for it were published
Since collisions existed within clipper it was possible to find a collision for the symmetric key with a fake symmetric key
8
Q
this was created because the U.S government needed a way to keep the communications from intelligence agents anonymous while overseas
A
why was
TOR
created
9
Q
what is the
Law Enforcement Access Field (LEAF)
generated by the clipper chip and what does it allow
A
this is a session key that has been:
- encrypted by said users unit key
- a hash of the encrypted session key generated
- the hash and encrypted session key combined and encrypted using the family key
this allows authoritys to decrypt communications of anyone they are investigating
10
Q
what are four
problems with banning the importation of encryption software
A
- Many everyday applications such as payment apps require encryption in order to work
- Encryption software can be easily smuggled in to a country
- The source code of encryption software is widely available on the internet
- The underlying mathematics of encryption is widely available and if one so wished could be used to mimic a specific type of encryption
11
Q
this is a computer that is currently connected to the TOR network and is able to relay messages and be part of a TOR circuit
A
what is a
TOR node
12
Q
this was split in half and split between:
- The US treasury
- The National Institute of Standards and Technology (NIST)
A
the
unit key of the clipper chip
was held in key escrow but how exactly was it held
13
Q
- Intercept the LEAF and the encrypted message
- Arrange with a judge that their unit key be released by the US treasury and the national institute of standards and technology (NIST)
- Decrypt the first layer of encryption using the family key
- Decrypt the second layer of the LEAF using the unit key revealing bob and alices symmetric key
- Decrypt the message using the symmetric key
A
how would law enforcement use the Law Enforcement Access Field (LEAF) if they were investigating alice or bob
14
Q
this was created by the
united states naval research laboratory
A
where was
TOR created
15
Q
this is a servers public key that has been hashed and then appended with .onion
A
how is a
.onion address created
16
Q
these make up most of the internet and are areas of the internet that either cannot be indexed or have had indexing restricted. These pages will probably exist only for authorised users such as existing behind a login screen
A
what is the
deep web
17
Q
you should keep the argument balanced that means creating a supporting claim that supports and opposes your main claim
A
when constructing an argument what is one important aspect that should be followed
18
Q
- Alice wishes to have secure and anonymous communication with bob so alice starts by building a circuit
- Alice contacts the directory node which holds a list of every node currently connected to the tor network
- Alice then selects at random a list of nodes from the directory node
- The nodes are then used to create a circuit
A
what are the four steps of building a
TOR circuit
19
Q
once alice has created an onion what are the three steps involved in sending it to bob
A
- alice sends the onion to the guard node in her tor circuit
- alices guard node decrypts the first layer of encryption to reavel a ciphertext and the next address to send the onion
- this process repeats until the exit node is reached which will decrypt the last layer of encryption to reveal alices message
20
Q
what two keys were held by the
clipper chip
A
the keys this held were:
- An 80 bit unit key - a unique key for each device
- A family key - a generic key, held by government
21
Q
- Single use addresses - addresses that are linked to one transaction only
- Multisignature bitcoins - these require the permission from multiple users to be spent
- Bitcoin tumblers - This mixes groups of bitcoin transactions and redistributes coins amongst users in theory making it impossible to link a single transaction
A
what are three
strategies that bitcoin has implemented to further protect the identity of those using bitcoin
22
Q
name three reasons that
key escrow failed
A
some reasons that this failed are:
- Can it be guaranteed that employees cannot steal keys
- Can it be guaranteed that there will be no misuse by government
- Can it be guaranteed that theft by hacking will not occur
23
Q
these are sites that cannot be visited by standard web browsers and rely on the tor network to exist. In essence a darknet is any site/page that is hidden from unauthorised users or requires specialist software to access
A
what is the
dark web / dark net
24
Q
this is a session key that has been:
- encrypted by said users unit key
- a hash of the encrypted session key generated
- the hash and encrypted session key combined and encrypted using the family key
this allows authoritys to decrypt communications of anyone they are investigating
A
what is the
Law Enforcement Access Field (LEAF)
generated by the clipper chip and what does it allow
25
what is the
## Footnote
**surface web**
this only accounts for a fraction of the material that exists on the web and can be indexed by search engines and accessed by anyone
26
why could TOR not be kept a secret and be used solely by the united states
keeping this a secret would mean that any communication on it would be linked back to america. instead it was made public
27
to alice what is an
## Footnote
**exit node**
the node furthest from alice and the last node of alices tor circuit and where data leaves the tor network
28
the node closest to alice and the first node of alices tor circuit where data enters the tor network
to alice what is the
## Footnote
**guard node**
29
what is another form of
**controlling the use of encryption software**
that has historically proposed
Another form of control that has been proposed is to allow citizens to use encryption but limit the key length meaning that there are less key values and it is possible to brute force the encryption
The suggestion is that the key length should be long enough that everyday hackers cannot brute force the key but short enough so that governments can
30
this stands for
## Footnote
**The Onion Router**
what does
**TOR**
stand for
31
how is a
## Footnote
**.onion address created**
this is a servers public key that has been hashed and then appended with .onion
32
what are the four steps of building a
## Footnote
**TOR circuit**
1. Alice wishes to have secure and anonymous communication with bob so alice starts by building a **circuit**
2. Alice contacts the **directory node** which holds a list of every node currently connected to the tor network
3. Alice then selects at random a list of nodes from the directory node
4. The nodes are then used to create a **circuit**
33
what is a
## Footnote
**TOR circuit**
this is a chain or path of computers (NODES) that allow a client and server to communicate with each other anonymously
34
what does
**TOR**
stand for
this stands for
## Footnote
**The Onion Router**
35
what does the TOR browser produce upon
## Footnote
**installation**
when this activity occurs the TOR browser will
## Footnote
**generates an asymmetric key pair and stores them in a secure vault on the hard drive**
36
1. Alices tor browser requests the public key of each node in her circuit in exchange for her own public key
2. After receiving alices public key Each node in alices circuit then creates a symmetric session key and creates a copy as well as creating a copy of their own public key
3. Each node then encrypts the copy of the session key and their public key using alices public key and forwards their message to alice
4. Alice now has the public key of each node in her circuit as well as a session key for each node
what are the four steps which involve alice and her tor circuit nodes
## Footnote
**creating and exchanging keys for encryption**
37
in five points when alice sends an onion message to bob what information is known by:
1. each of the nodes (3 points)
2. bobs computer (1 point)
3. eve monitoring connections to bobs computer (1 point)
1. The guard node cannot tell if alice was a relay or if the message originated from her
2. Each node stores the address of the node that it receives the message from
3. Each node is only aware of the address before it and the address after it
4. Bobs computer only knows the address of alices exit node
5. If eve is monitoring the connection to bobs computer it will look as though the exit node has made the request to bobs computer
38
to alice what is the
## Footnote
**guard node**
the node closest to alice and the first node of alices tor circuit where data enters the tor network
39
when constructing an argument what is one important aspect that should be followed
you should keep the argument balanced that means creating a supporting claim that supports and opposes your main claim
40
1. When bob reply s to the message that Alice sent is he will first send his message to the exit node in Alice's circuit
2. The exit node will then use the symmetric key it shared with Alice to encrypt bobs message
3. The exit node will then pass the encrypted message on to the address it has stored for the original request
4. The next node then carries out steps 2 and three and so on until the message reaches Alice
5. When Alice receives the message from her guard node she will decrypt the onion using each of the symmetric keys that she has stored for each of the nodes
explain in five steps the process of bob replying to alices message via the
## Footnote
**TOR network**
41
why was
**TOR**
created
this was created because the U.S government needed a way to keep the communications from intelligence agents anonymous while overseas
42
what is a
## Footnote
**TOR directory node**
this is a computer that holds and maintains a directory of every node currently connected to the TOR network
43
this only accounts for a fraction of the material that exists on the web and can be indexed by search engines and accessed by anyone
what is the
## Footnote
**surface web**
44
what two components MUST an
**argument**
made up of
this MUST contain:
1. **a main claim**
2. **a supporting claim or reason**
45
if alices TOR circuit nodes are 2, 5, 8, 17, 22
how does alice go about encrypting her message to bob and
**creating an onion**
1. The first round of encryption will encrypt the message using the exit node (22) public key
2. The second round of encryption will encrypt the ciphertext from step 1 with the address of the exit node (22) using the relay node (17) public key
3. The third round of encryption will encrypt the ciphertext from step 2 with the address of the relay node (17) using the relay node (8) public key
4. And so on…
46
who is involved in
## Footnote
**funding the maintenance of the TOR network**
the following are involved in which activity:
1. US state department
2. national science foundation
3. swedish government
4. individual donors who wish to donate
47
what are the names of the three mathematicians that were
## Footnote
**tasked with creating TOR**
what were these three mathematicians tasked with
1. paul syverson
2. micheal reed
3. david goldschlag
48
what were these three mathematicians tasked with
1. paul syverson
2. micheal reed
3. david goldschlag
what are the names of the three mathematicians that were
## Footnote
**tasked with creating TOR**
49
what was the
## Footnote
**clipper chip**
this was a chip that america wanted installed inside every machine that was manufactured or imported into the US.
the chip would enable authoritys to decrypt any communications if they so wished
50
1. The guard node cannot tell if alice was a relay or if the message originated from her
2. Each node stores the address of the node that it receives the message from
3. Each node is only aware of the address before it and the address after it
4. Bobs computer only knows the address of alices exit node
5. If eve is monitoring the connection to bobs computer it will look as though the exit node has made the request to bobs computer
in five points when alice sends an onion message to bob what information is known by:
1. each of the nodes (3 points)
2. bobs computer (1 point)
3. eve monitoring connections to bobs computer (1 point)
51
1. alice sends the onion to the guard node in her tor circuit
2. alices guard node decrypts the first layer of encryption to reavel a ciphertext and the next address to send the onion
3. this process repeats until the exit node is reached which will decrypt the last layer of encryption to reveal alices message
once alice has created an onion what are the three steps involved in sending it to bob
52
these are nodes between the first node and the last node of the circuit
what are
## Footnote
**Relay nodes / intermediate nodes**
53
1. The first round of encryption will encrypt the message using the exit node (22) public key
2. The second round of encryption will encrypt the ciphertext from step 1 with the address of the exit node (22) using the relay node (17) public key
3. The third round of encryption will encrypt the ciphertext from step 2 with the address of the relay node (17) using the relay node (8) public key
4. And so on…
if alices TOR circuit nodes are 2, 5, 8, 17, 22
how does alice go about encrypting her message to bob and
**creating an onion**
54
this is maintained by
## Footnote
**the tor project inc**
who maintains the
## Footnote
**TOR network**
55
what are the four steps which involve alice and her tor circuit nodes
## Footnote
**creating and exchanging keys for encryption**
1. Alices tor browser requests the public key of each node in her circuit in exchange for her own public key
2. After receiving alices public key Each node in alices circuit then creates a symmetric session key and creates a copy as well as creating a copy of their own public key
3. Each node then encrypts the copy of the session key and their public key using alices public key and forwards their message to alice
4. Alice now has the public key of each node in her circuit as well as a session key for each node
56
this is an idea that was proposed in both the US and UK and involves having a third party hold a copy of all encryption keys used by software
what is a
## Footnote
**key escrow**
57
what are
## Footnote
**Relay nodes / intermediate nodes**
these are nodes between the first node and the last node of the circuit
58
1. Alice and bobs clipper chips negotiate a symmetric key
2. Alice encrypts her message using the symmetric key
3. Alice encrypts the symmetric key using her unit key
4. The encrypted session key is combined with a hash and re encrypted with the family key generating what is called a Law Enforcement Access Field (LEAF)
5. Alice sends the encrypted message and LEAF to bob
6. Bob discards the LEAF and decrypts alices message using the agreed symmetric key
describe the six steps of how secure communication is acheived using the clipper chip
59
when this activity occurs the TOR browser will
## Footnote
**generates an asymmetric key pair and stores them in a secure vault on the hard drive**
what does the TOR browser produce upon
## Footnote
**installation**
60
describe the six steps of how secure communication is acheived using the clipper chip
1. Alice and bobs clipper chips negotiate a symmetric key
2. Alice encrypts her message using the symmetric key
3. Alice encrypts the symmetric key using her unit key
4. The encrypted session key is combined with a hash and re encrypted with the family key generating what is called a Law Enforcement Access Field (LEAF)
5. Alice sends the encrypted message and LEAF to bob
6. Bob discards the LEAF and decrypts alices message using the agreed symmetric key
61
what is the
**main claim**
within an argument
this is a claim or statement that you would like your audience to believe
62
this is a chain or path of computers (NODES) that allow a client and server to communicate with each other anonymously
what is a
## Footnote
**TOR circuit**
63
this is a computer that holds and maintains a directory of every node currently connected to the TOR network
what is a
## Footnote
**TOR directory node**
64
what encryption algorith did the
**clipper chip**
use
this used the
## Footnote
**skipjack symmetric algorithm**
65
some reasons that this failed are:
1. Can it be guaranteed that employees cannot steal keys
2. Can it be guaranteed that there will be no misuse by government
3. Can it be guaranteed that theft by hacking will not occur
name three reasons that
## Footnote
**key escrow failed**
66
this was a chip that america wanted installed inside every machine that was manufactured or imported into the US.
the chip would enable authoritys to decrypt any communications if they so wished
what was the
## Footnote
**clipper chip**
67
1. Many everyday applications such as payment apps require encryption in order to work
2. Encryption software can be easily smuggled in to a country
3. The source code of encryption software is widely available on the internet
4. The underlying mathematics of encryption is widely available and if one so wished could be used to mimic a specific type of encryption
what are four
## Footnote
**problems with banning the importation of encryption software**
68
keeping this a secret would mean that any communication on it would be linked back to america. instead it was made public
why could TOR not be kept a secret and be used solely by the united states
69
where was
## Footnote
**TOR created**
this was created by the
## Footnote
**united states naval research laboratory**
70
the following are involved in which activity:
1. US state department
2. national science foundation
3. swedish government
4. individual donors who wish to donate
who is involved in
## Footnote
**funding the maintenance of the TOR network**
71
explain in five steps the process of bob replying to alices message via the
## Footnote
**TOR network**
1. When bob reply s to the message that Alice sent is he will first send his message to the exit node in Alice's circuit
2. The exit node will then use the symmetric key it shared with Alice to encrypt bobs message
3. The exit node will then pass the encrypted message on to the address it has stored for the original request
4. The next node then carries out steps 2 and three and so on until the message reaches Alice
5. When Alice receives the message from her guard node she will decrypt the onion using each of the symmetric keys that she has stored for each of the nodes
72
what are three
## Footnote
**strategies that bitcoin has implemented to further protect the identity of those using bitcoin**
1. **Single use addresses** - addresses that are linked to one transaction only
2. **Multisignature bitcoins** - these require the permission from multiple users to be spent
3. **Bitcoin tumblers** - This mixes groups of bitcoin transactions and redistributes coins amongst users in theory making it impossible to link a single transaction
73
who maintains the
## Footnote
**TOR network**
this is maintained by
## Footnote
**the tor project inc**
74
what is a
## Footnote
**key escrow**
this is an idea that was proposed in both the US and UK and involves having a third party hold a copy of all encryption keys used by software
75
what is the
## Footnote
**dark web / dark net**
these are sites that cannot be visited by standard web browsers and rely on the tor network to exist. In essence a darknet is any site/page that is hidden from unauthorised users or requires specialist software to access
76
what is the
## Footnote
**deep web**
these make up most of the internet and are areas of the internet that either cannot be indexed or have had indexing restricted. These pages will probably exist only for authorised users such as existing behind a login screen
77
this is a statement that will support your main claim it is often the why of your claim and may start with words such as (for example, because, therefore, so)
what is a
**supporting claim or reason**
within an argument
78
what is a
**supporting claim or reason**
within an argument
this is a statement that will support your main claim it is often the why of your claim and may start with words such as (for example, because, therefore, so)
79
Another form of control that has been proposed is to allow citizens to use encryption but limit the key length meaning that there are less key values and it is possible to brute force the encryption
The suggestion is that the key length should be long enough that everyday hackers cannot brute force the key but short enough so that governments can
what is another form of
**controlling the use of encryption software**
that has historically proposed
80
this MUST contain:
1. **a main claim**
2. **a supporting claim or reason**
what two components MUST an
**argument**
made up of
81
1. Weaknesses were found with the hash authentication of the LEAF being that collisions were present
2. Later it was found that skipjack itself was not strong as it was cracked just days after the documents for it were published
Since collisions existed within clipper it was possible to find a collision for the symmetric key with a fake symmetric key
why did the
## Footnote
**clipper chip fail**
82
the node furthest from alice and the last node of alices tor circuit and where data leaves the tor network
to alice what is an
## Footnote
**exit node**
