Challenge-response authentication is a family of protocols in which one party presents a question ("challenge") and another party must provide a valid answer ("response") to be authenticated.

learn more… | top users | synonyms

3
votes
1answer
714 views

Is this DIY remote lock protocol secure?

I need your advice on following scheme of exchange protocol between remote lock and key. I'm planning to use following algorithm: Key generates unique value that never repeats (in reality it's just ...
0
votes
1answer
23 views

Proof of Knowledge/Data Integrity using Hash Function

Objective: A verifier wants to ensure that a block of data M is also known to a prover. The protocol should exchange little information and should not leak information about the value of M. Proposed ...
2
votes
0answers
16 views

StoredKey in Salted Challenge Response Mechanism (SCRAM)

In SCRAM (RFC5802, page 8) the client generates ClientKey to server, which is a derivation of the original password. This is communicated to the server in a secure ...
4
votes
2answers
262 views

Is there a difference between asking for a signature and asking for a decryption in challenge-response authentication?

Consider the following two authentication schemes. In both cases the server knows a public key of the client (for a signature system in the first and an encryption system in the second case). Scheme ...
3
votes
1answer
122 views

Proof that two parties can communicate

Suppose we have three parties, Alice, Bob, and Carol. Alice can receive messages from Bob and Carol individually, but can only send messages to both simultaneously. Additionally, Alice cannot tell if ...
3
votes
1answer
139 views

Is there a scheme that allows to use RSA based challenge response protocol limited to signing only 8 bytes to create a secure signature of any data?

I have a tiny device that has a challenge-response authentication mechanism where the device signs 8 bytes of any data with it's internal 2048 bit RSA key. I would like to be able to certify any data ...
0
votes
1answer
104 views

Why should I use X.509 Authentication over PKC based Authentication?

So I have two examples and I don't understand why one would be chosen over the other. Example 1. A sends EPUb[r1] to B (asks B to prove knowledge of ...
2
votes
1answer
84 views

Can adding nonces make challenge response authentications weaker?

In a custom protocol we want to replace an aged tiger32 based challenge response authentication. I suggested that we use something existing, so threw HMAC into the room. As per wikipedia it works as: ...
2
votes
0answers
353 views

Challenge-response based on public-key decryption, why send public key

Quoting the handbook of applied cryptography, chapter 10.3.3 (i): Identification based on PK decryption and witness. Consider the following protocol: $A \leftarrow B: h(r), B, P_A(r,B)$ ...
4
votes
2answers
222 views

Spoofing protocol nonce

Amy and Betty have a shared key $k$, and the protocol below is to provide a mutual authentication for both Betty and Amy. A sends B : $n_a$ B sends A : $n_b \;\|\; E(k, n_a)$ A sends B : $E(k, n_b)$ ...
1
vote
0answers
138 views

Challenge–response authentication which can be done in head?

Say we have door where you have to say a password to pass. If theres someone standing nearby he would hear the password and could also use it. So therefore the doorman gives you a different number ...
1
vote
1answer
79 views

Why send a challenge with CHAP?

I have been reading about the Challenge-Handshake authentication Protocol (aka CHAP). Why send a challenge to the user and ask them to hash that challenge with the symmetric key and send that hash ...
1
vote
2answers
377 views

Help me describe/identify this challenge-response protocol/algorithm?

My area of expertise is reverse engineering, specifically embedded systems. I do attack cryptographic systems, but this largely involves key recovery or exploiting the implementation. I was asked to ...
3
votes
2answers
271 views

Zero-Knowledge Challenge-Responce Protocol

Good day to everyone. I am trying to implement an e voting system (just for reference -it is not important though-it is described at the Internet Voting Protocol Based on Improved Implicit Security ...
4
votes
2answers
349 views

What challenge should I use in a challenge-response proof-of-work?

In order to guard against denial-of-service attacks, I want to require clients to do some work (more work than the server does fulfilling the request) before talking to them. Client connects Server ...
1
vote
1answer
147 views

How is the password sent across for verification?

I am familiar with Challenge-Response Authentication scheme. However I would like to know actual message content sent between client and server for 1 way authentication, over an insecure channel. ...
2
votes
1answer
742 views

Hash or encryption function for challenge-response protocol?

Say I have an authentication protocol where the shared secret is never transmitted. The server passes a challenge to the client and the client calculates a response using an algorithm where the ...