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5
votes
1answer
496 views

Proof of correct construction of a private key in distributed cryptography

In an exponential ElGamal encryption scheme where the key generation is done in a distributed way among $n$ trustees we have that each trustee $i$ (where $1 \leq i \leq n$): Selects a private key ...
4
votes
2answers
5k views

How is the key shared in symmetric key cryptography?

Symmetric key cryptography is an encryption system in which the sender and receiver of a message share a single, common key that is used to encrypt and decrypt the message. Is the key public or it is ...
3
votes
1answer
130 views

Combining two hashing functions

I have been working on a Bloom Filter implementation recently and after a discussion with a co-worker about how many hashing functions to use I told him I was limited with using hashing functions that ...
2
votes
1answer
260 views

Public Keys on Social Media

Is there any problem with using social media (i.e. Facebook) as a directory of public keys? For example, couldn't Alice put a note containing $(g^a \bmod p, g, p)$ on her Facebook page so she could ...
2
votes
1answer
76 views

One time pad ciphers in emails

In order to achieve very high security for privacy, would it be cryptographically secure to use one time pad ciphers in emails? The distribution of the keyword would pose no problems since I would ...
2
votes
0answers
72 views

What are the current known weaknesses/attacks on quantum key distribution?

I am writing a paper on the implementation of QKD in the future. I want to know if there are any viable attacks on the BB84 protocol or QKD in general? I know of the Photon Number Splitting attack or ...
1
vote
1answer
66 views

How are onetimepads distributed?

OTP encryption is unbreakable as it seems. I have read some stuff (wiki, blogpost, etc.) but i would not find any information how they are used. If i wanted to create a messenger service, how would i ...
1
vote
1answer
236 views

Traitor-tracing PRF

I'm looking for a pseudorandom function (PRF) with "traitor-tracing" properties. More specifically, I'd like there to be multiple equivalent keys, so I can give different parties different keys, but ...
1
vote
2answers
283 views
1
vote
1answer
126 views

Problem in understanding Blakley's Secret Sharing Scheme

I need to implement Blakley's Secret Sharing Scheme. I have read below mentioned two research papers but still unable to understand how to implement it. Safeguarding cryptographic keys Two Matrices ...
1
vote
3answers
55 views

Possible to generate a one time secret which all nodes on the distributed network can know but cannot pre compute

I have a distributed P2P network. Everyday, I want each node to have a secret which is only valid for that day, while each of the other remaining nodes on the network will be able to calculate the ...
1
vote
0answers
90 views

How to distribute symmetric key between $n$ entities?

If there are $n$ servers for broadcasting a symmetric key in such a manner that following holds: No server alone can find the key $K$ alone. Any two servers can pass $k_i$ and $k_j$ such that $K=f(...
0
votes
3answers
161 views

Updating the secret key used for HMAC

I am designing a distributed system, composed by a set of physically distributed embedded devices (8 bit cores with less than 1 KB of RAM). The devices need to be able to authenticate the originator ...
0
votes
0answers
32 views

Security or not in Key distribution

For example, There are 3 clients. I want to deliver specific value $x$ to all clients. $x\leftarrow {0,1,2,...,q-1}$ where q is a large prime number. By using function $f(x)=x*y_{i}*z_{i}$ where i=...
0
votes
0answers
52 views

How does Blom's scheme work?

How does Blom's scheme work? Is the polynomial expression of it a normal one? A few additional questions: How big does the prime modulus need to be? Can it be bigger than the size of the derived ...
-1
votes
1answer
48 views

In Needham Schroeder key distribution what happens if responder's part is not encrypted in step 2 with Kbs but encrypted instead by Kab in step 3

The Needham-Schroeder protocol is: 1 A→S:A,B,Na 2 S→A:{Na,B,Kab,{Kab,A}Kbs}Kas 3 A→B:{Kab,A}Kbs 4 B→A:{Nb}Kab 5 A→B:{Nb−1}Kab Here Na and Nb are nonces. Kab is the key between a and b Kas is ...
-2
votes
1answer
510 views

What are the advantages of Certificate Authority and Key Distribution Center over each other?

I want know difference among them. What are advantages/disadvantage of one on other?