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 ...

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165 views

Is it possible take a piece of data in secret?

I want something like this, but in a digital sense: You and others walk into a room. Everyone knows who each of you are and everyone is doing their best to figure out what piece of paper each ...
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281 views

Is the SILC protocol still used? [closed]

I'm looking into implementing a private SILC server for friends (and possibly their friends). And after visiting the Wikipedia entry for SILC protocol, it seems all the official pages linked at the ...
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52 views

Yaos Millionaire Problem: Why distance >= 2?

I'm currently reading about Yao' Millionaire Problem: http://research.cs.wisc.edu/areas/sec/yao1982-ocr.pdf Alice and Bob want to know which of them is richer. Let $j \in \{1, \cdots 10\}$ be Bobs ...
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31 views

Security of a lightweight heartbeat protocol

I am implementing a heartbeat protocol so that a server can send notifications to clients. The notifications are not occurring so often, so I don't want to keep an open TCP+TLS session for each ...
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3answers
124 views

List of post quantum cryptography protocols [closed]

What are the post quantum cryptography protocols that have been proposed until now? I know about McEliece cryptosystem, and LWE scheme. What are the others? Can you provide me a list or a website ...
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66 views

When we use one time pad TWICE in two different ways

Assumption and Notations: All the values defined over the field $\mathbb{F}_p$, where $p$ is a large prime number. We denote multiplicative inverse of value $v$ by $v^{-1}$. All values are non-zero ...
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19 views

Security issues with self encryption? [duplicate]

I'm thinking about the scenario of using a set of (potentially untrusted) hosts to store (potentially private) files. Think something like distributed backup where you contribute some disk space and ...
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1answer
110 views

Authentication protocol which detects client impersonation from another machine

Consider following authentication protocol. Client ClientA knows some initial secret KeyA shared with server. Client also knows IP of legitimate server. Now when client wants to establish connection ...
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40 views

Is this ECC based messaging method secure?

I developing an encrypted messaging for ZeroNet (aP2P file-based network, website: zeronet.io) and would like to have some guidelines if any of this could work. My first idea: In ZeroNet every user ...
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101 views

Simplest way for strong cryptography in chat

I am a beginner in cryptography and I am interested for several weeks on this for my chat application. Basically, it is a centralized model. All messages are stored and potentially visible by ...
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68 views

What is the lightweight key exchange protocol of choice?

Assume I have to implement a secure channel protocol by myself. Assume further that for some obscure reasons (library restrictions?) I can't use any of the pre-made libraries for SSH, TLS and such. ...
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52 views

Details related to the ZIP algorithm used in PGP message encryption? [closed]

I am very new to PGP. PGP encryption works with hash function, asymmetric encryption, symmetric encryption and a zip algorithm (LZ77). What I know is that the zip algorithm is used to reduce the ...
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3answers
86 views

Is it possible to encrypt a message's destination as well as its content?

I have imagined a way to break through any kind of censorship but since I don't have enough professional knowledge of cryptography I don't know whether it is feasible or not. If there is a method ...
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54 views

Encryption with a known plaintext

I'm building an application where users can be a part of groups, and can obtain and distribute URLs from the group page that allow anyone who clicks on them to join said group. Groups should not ...
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64 views

Obliviously computing the Least common multiple of two poylnomials

Consider I have two polynomials $f_1$ and $f_2$ of the same degree. I want to secure them (using any kind of encryption except FHE) and outsource them to an untrusted server. I want him to compute the ...
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78 views

Efficient proof of knowledge using Wegman-Carter hash

A verifier wants to ensure, with only little exchange of data with other systems, that a large block of data $M$ that the verifier holds is also available to some other system(s). It is not an ...
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43 views

Hybrid fair exchange protocol

A gradual fair exchange (layman term) is a form of fair exchange protocol where Alice will transfer 1 bit to Bob then Bob will transfer 1 bit to Alice. The flaw with this protocol is that the party ...
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130 views

ECC cryptography with shorter signature when not needing high security?

I am new here and fairly new to cryptography, so if I say something wrong, let me know. I am trying to set up a system where a user can receive a temporary license key over the phone, put it into ...
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90 views

A question or few about Mental Poker

I have spent some time studying the "Mental Poker" protocol (sometimes called SRA), initially proposed by Shamir, Rivest, and Adleman -- ...
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1answer
102 views

Use additional keys to thwart key compromise?

Is it good or bad practice to design crypto protocols for key compromise by using additional keys? Argument for bad practice would be: When you have a key you should trust it and not throw more keys ...
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65 views

Is container format relevant to security of encrypted message inside?

Still trying to design a fully binary cryptography container format for my mobile app, I am here asking if container is ever relevant. Thanks to Apple, I cannot use GPG directly because I can neither ...
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138 views

Should layered use of crypto always have a cryptographic binding between the layers?

Reading the latest TLS weakness, it seems that multiple weaknesses have been found over the years caused by not ensuring that messages are sent over the same channel, and in general a lack of ...
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189 views

What would make it impossible to deny that decryption of a package has taken place?

I'm part of a team designing a system where a user have to be able to read a certain package, if he has preformed an action or series of actions that makes it legal for him to do so. The tricky part ...
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116 views

Could MITM securely identify identity?

Consider protocol like QUIC or MinimaLT which are essentially layer4 replacement for TCP/UDP (riding on top of UDP currently because of fear of random firewalls dropping new L4 protocol). From crypto ...
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191 views

Is this hypothetical key-exchange secure?

I've thought about the following (generic) key-agreement protocol. The only weaknesses I could have found are missing freshness guaranteees. As for the notions: $E^1_K(P)$ is the symmetric encryption ...
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2answers
172 views

Voting system validation

I'm developing an application to run elections. A voting system. I would like to give the ability to the voters to check later if their vote were correct computed/casted. assumptions: each user has ...
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1answer
80 views

How to hash a structure that needs to include that hash's outcome?

so I am busy writing a TCP protocol in which I send a "packet header" with each packet of data. This packet header is a structure that contains information about the data that was sent. I want to ...
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107 views

Two-party equality computation

Alice and Bob each secretly chooses an integer between 1 and 10, a and b. They want to know (with high probability) whether or ...
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70 views

Rationale of “r” AES key use in OTR version 3 AKE protocol?

I just tried to review & understand AKE (Authenticated Key Exchange) protocol as defined in OTR secure messaging protocol version 3 here , and aiming to achieve Perfect Forward Secrecy I am a ...
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343 views

How to secure a mental poker protocol? [closed]

I would like to implement a mental poker protocol in a secure fashion. How should I go about that without (preferably) infringing on the Mental Poker Framework patent?
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1answer
163 views

Combatting traffic shape analysis with spurious packets

I was reading a question about combatting traffic analysis, and a thought occured. If I send random junk messages periodically, would that defeat traffic analysis? The messages would contain some ...
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1answer
169 views

Key management protocol for end-to-end security on Advanced Metering Infrastructure

I am currently working on a research on end-to-end security implementation for Advanced Metering Infrastructure (AMI). Pardon me if I a bit off topic or not asking the right question as I am ...
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1answer
201 views

Is this chat protocol safe?

I am in the design phase of a secure chat application at the moment. I am trying to make this as secure as possible. The Serverprovider should not have access to the messagedata. So my idea was the ...
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1answer
134 views

Is it possible to hand-negotiate an SSL/TLS session?

I'm interested in trying to hand-negotiate an SSL/TLS session. Similar to how one would use telnet to port 80 and type GET / HTTP/1.1. I know there's a lot of steps ...
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12 views

Two nodes in p2p network exchange data and read data in same time [closed]

I want to finde paper about exchange data between two nodes in p2p network. They must read each other's data in same time. In example two player a,b play rock scissors paper. A must read b's data ...
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1answer
53 views

Creating a message authentication scheme

I have such situation. I have a device like dongle. But it has certain limitations. For example, it can only have implemented encryption and decryption functionality. The availability of ciphers ...
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21 views

Shamir SS: To associate shares to the public values $x_i$, when the shares are permuted [duplicate]

Suppose we use $(t,n)$ Shamir secret sharing as follows: We share the secret $\beta$ as $S=[s_1,..., s_n]$, where $X=[x_1,...,x_n]$ are the public values. For the sake of simplicity, lets assume ...
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44 views

AM protocol for 2 distinct objects

Prover is going to convince verifier that 2 objects are distinct, do you know any Arthur-Merlin protocol for this problem?
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49 views

Role of trusted party in the Ideal model in Malicious case

Imagine there is a protocol supporting outosurced multi party computation. There are three parties involved in the protocol: client $A$, client $B$ and a server. Client $A$ and $B$ send their private ...
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2answers
56 views

Why does spiped use both nonces and ephemeral keys?

Colin Percival's spiped utility uses a pre-shared key and Diffie-Hellman with ephemeral keys to provide forward secrecy. The protocol is summarized in the ...
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1answer
70 views

Non-repudiation and digital signature of a dishonest participant

Let's assume a dishonest Alice who sends, encrypts & digital signs a message to Bob. Bob stores the decrypted message and the digital signature in a database. However Alice is a bad girl and ...
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1answer
102 views

Oblivious transfer variation question

Now I am doing a variation of the oblivious transfer, I have to use 2 people, pebbles, and boxes. I need to find out if who has a larger number between Alice and Bob (variation of Yao's Millionaires' ...
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144 views

Going Blind, Group or Ring?

I have several problems approaching the following problem: Let's assume that we have Alice, Bob and Cathy. Alice wants to present a message to Cathy, showing her that someone else has signed it (Bob), ...
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3answers
390 views

Would it be possible to create a game where one would need to decrypt a simple encryption?

This might sound pretty weird, but I was thinking of a game a person could play alone with a pen and paper. I got this idea where the person would write a random four letter string on a paper, and ...
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44 views

Correlated or biased coin protocols?

There are a number of papers in the literature describing secure/fair coin flipping protocols. Unfortunately in my case, I am looking for coins that are epsilon-biased or epsilon-correlated. I am ...
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1answer
56 views

Share two secrets between two parties [duplicate]

Alice has a secret A, Bob has a secret B. They have a secure channel and a MAC. They each want to know the other's secret, but don't particularly want to give up their own. However, neither will not ...
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1answer
158 views

Burn after read algorythm. Software verification on compromised environment. Software smart card

Please help me pick right design of software… I have to design client-server software, where the server should verify that the client runs software from specific source code. It has to be verifiable ...
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1answer
80 views

Can we use merely permutation to hide a message?

This question is related to this: When all shares of a secret are given to adversary as a permuted matrix I think the below question is a simplified version of that. Assume we have a 40-bit ...
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2answers
1k views

Where to store the private key and the public key in a communication protocol

I want to create a simple secured connection protocol over TCP/IP. I just want to connect from my mobile device to a server securely. Firstly I thought to use an SSL connection, but I changed my ...