Cryptography Stack Exchange
Cryptography Stack Exchange

Questions tagged [protocol-design]

Design of cryptographic protocols, i.e. ways of using algorithms (primitives) to achieve one or more security goals like integrity, confidentiality, authenticity (maybe together with non-security-related goals). If you ask about a specific protocol, tag with its name instead (or additionally, if about its design).

Design of cryptographic protocols, i.e. ways of using algorithms (primitives) to achieve one or more security goals like integrity, confidentiality, authenticity (maybe together with non-security-related goals). If you ask about a specific protocol, tag with its name instead (or additionally, if about its design).

Background:

If you want to know about design of cryptographic primitives, see instead.

For example, many protocols involve a data compression algorithm, a secrecy-preserving encryption algorithm, and an authentication algorithm. Questions asking why we apply them in that order -- such as a or b -- should be tagged .

Some protocol-specific tags: (also for TLS), , ,

702 questions
14
votes
4 answers

Is there a way to optimize a linear scan while preserving anonymity?

I've been wrestling with a problem, and I was hoping if someone else had a bright idea. Here's the problem: I have two sides, Alice and Bob. Alice has a single high entropy string $A$, and Bob has a number of high entropy strings $B_i$, one of…
poncho
  • 147,019
  • 11
  • 229
  • 360
13
votes
8 answers

Two mutually untrusted parties want to exchange data: how to ensure each one gets the data it needs?

I am trying to come up with what could maybe be a novel algorithm for an application I am writing. Client A has a file fA. Client B has file fB. Each party is untrustworthy and will try to rip off the other party. Client A wants the fB and client B…
Anon21
  • 237
  • 1
  • 7
12
votes
4 answers

Is there any protocol for proving that a message was written at a certain time?

Does there exist a way to cryptographically prove that a message was written at a certain time? I know that one can write messages in bitcoin transactions to that the message is preserved in the blockchain, which can be used to prove the message was…
Christine Sheng
  • 121
  • 2
12
votes
5 answers

How to use proof of lack of knowledge?

This is a purely hypothetical example but is provable ignorance useful in cryptography? For example, let's say I have a trapdoor collision resistant function. I know the trapdoor and therefore some $x_0 \neq x_1$ such that $f(x_0) = f(x_1)$. This is…
user1936752
  • 737
  • 1
  • 4
  • 16
12
votes
4 answers

Alice and Bob's crush

Suppose Alice and Bob both want to determine whether the other has a crush on him/her, but they only wish to share the information if the crush is mutual. Is there a cryptographic protocol that makes this possible without using trusted third…
user24215
  • 121
  • 2
11
votes
1 answer

Why was WEP apparently not reviewed by many cryptographers?

According to this analysis of WEP, These attacks point to the importance of inviting public review from people with expertise in cryptographic protocol design; had this been done, the problems stated here would have surely been avoided. It is my…
Henry Elliott
  • 211
  • 1
  • 2
10
votes
1 answer

A fair peer-based coin-flipping protocol?

I found this question on the game programming site and was intrigued. I came up with an answer off the top of my head but I'm no cryptanalyst so it is probably not water-tight. This is how my idea goes: each of the two peers generates a random…
Michael Slade
  • 201
  • 2
  • 5
9
votes
1 answer

Any problems with this secure time synchronization scheme?

I have a time authority and I want to securely set a client's time to this authority's time/date within a precision of $\delta$ seconds. The authority's public key is known to the client. This was my idea: A client sends a request with a 128-bit…
orlp
  • 4,230
  • 20
  • 29
8
votes
3 answers

What kind of adversary is the cloud?

I just started some work on computation over encrypted data in the cloud. We're still in the early planning stages, and to really understand the kind of security we can offer I need to determine what kind of attacks to expect from an untrusted cloud…
pg1989
  • 4,636
  • 23
  • 42
8
votes
3 answers

Is it possible to create a "proof-of-upload" system for BitTorrent ratio tracking?

One issue that private BitTorrent trackers that track users' share ratios often run into is how to keep track of people who are screwing with their upload statistics, something known as "stat-hacking". As it is, because uploading and downloading is…
Joe Z.
  • 408
  • 2
  • 10
7
votes
2 answers

What does well-typed mean?

I am currently studying Cryptography and I don't really understand what does 'well-typed' mean when talking about secure cryptographic protocols. I can't find any reasonable explanation on the internet either. It would be great if someone could give…
user1880405
  • 173
  • 1
  • 5
7
votes
1 answer

How does one design a traffic analysis resistant protocol?

I'm curios about protocols which leak considerable personal information, like instant messaging exposing the contacts relation. How does one make an instant messaging protocol which is resistant to traffic analysis? I'm interested most specifically…
Jeff Burdges
  • 1,116
  • 5
  • 16
6
votes
2 answers

Protocol to identify zone of potential agreement without revealing reservation prices and having to trust third parties?

A wants to buy a company from B. Before A and B enter negotiations, they want to make sure that there actually is a zone of potential agreement. Obviously, they don't want to communicate their reservation prices to the other party (A only buys for…
RudolfKaiser
  • 373
  • 2
  • 5
5
votes
1 answer

Designing a protocol to record attendance to lectures

Scenario: a class that is not mandatory. The teacher wants a protocol that will satisfy the following requirements: It must record each student's attendance. A student X should not be able to say that another student Y went to the lecture. The…
Maria Ines Parnisari
  • 256
  • 1
  • 6
5
votes
2 answers

What requirements would lead to the development of a new security protocol?

I recently completed a semester studying some basic amount of cryptography. So my knowledge is not very broad/deep. What I currently see is that we have a bunch of fairly secure encryption modes to encrypt data and fairly secure authentication…
Limit
  • 417
  • 4
  • 13
1
2 3 4 5