Authentication is successfully validating that an entity you are communicating with is actually who they claim to be. The entity typically demonstrates who they are by showing they possess a secret that only they could know.

learn more… | top users | synonyms

4
votes
1answer
110 views

Encrypting a TCP connection between two unknown nodes

I'm writing an application for controlling computers from a client. I'd very much like it if the connection is secure and only authenticated clients are allowed access. The workflow will be ...
5
votes
2answers
81 views

Why is this authentication procedure using Rabin crypto not useful?

A friend asked me the following, pointing out that the method is not very useful (my problem is I do not see why it is not good): Consider a person A which chooses $n$ as the public key for the ...
4
votes
3answers
353 views

How to perform authentication without central server in P2P?

How you be sure that the man who you're talking with is the one who you think he is? I.e. how to perform authentication in P2P network without central trust server or Certificate Authority? I'm just ...
2
votes
1answer
184 views

Is this new server API authentication protocol secure?

I need a secure protocol to authenticate client side users with my server which has an API. I am devising something more secure particularly to resist active MITM attacks where an attacker may modify ...
4
votes
1answer
1k views

What is “Implicit Authentication”?

What is “Implicit Authentication” in the context of authentication methods? I searched the Web but could not find any article that describes this. If anyone can describe it, that would be a great ...
0
votes
1answer
75 views

A replay attack question

Which of the following protocols is susceptible to replay attack :- 1) A -----> B username, password 2) A -----> B username, h(timestamp,password) 3) A -----> B username timestamp, ...
0
votes
2answers
260 views

Can a salt for a password hash be public?

For my understanding salts in password hashes are used to prevent the precompuation of plaintext$\to$hashvalues (rainbow tables). I know from different threads, it is not necessary to keep the salt ...
9
votes
1answer
200 views

Shadowed identity in cryptography

I was trying to implement zero knowledge protocol for authentication based on the paper "A Practical Zero-Knowledge Protocol Fitted to Security Microprocessor Minimizing Both Transmission and Memory". ...
0
votes
0answers
41 views

How to select parameters based on some condition

I am implementing a protocol for authentication where parameters need to be selected with $gcd(\mu,\phi)=1$ where $\phi=(p−1)(q−1)$. What is the best way to select the parameters while implementing
3
votes
1answer
129 views

What does this Authentication protocol achieve and what information is shared?

I'm having trouble with the following question from my class: "What is the purpose of the protocol, and how does it achieve this purpose and what shared information does A and B end up after ...
3
votes
1answer
117 views

How to attack this authentication protocol from “Cryptography: An introduction”

Consider the following protocol (from the book "Cryptography: An introduction", by Nigel Smart): ...
2
votes
1answer
168 views

Off-the-record communication

Is my protocol correct? For fun, I tried to design a protocol that would allow off-the-record communication. I'm not sure it works, I have a feeling there might be a problem with it that I'm not ...
14
votes
3answers
3k views

Specification of the Megamos crypto algorithm

It has recently emerged that a paper that was scheduled to appear at Usenix Security 2013, titled "Dismantling Megamos Crypto: Wirelessly Lockpicking a Vehicle Immobiliser", has been censored ...
2
votes
1answer
92 views

Proof of shared secret through key derivation

Alice gives a random key $K$ (e.g. 32 bytes long) to Bob through a secure channel. Bob want to prove to Alice through an unsecured channel that he knows the key. Is it secure for Bob to send ...
2
votes
1answer
89 views

With Encrypt-then-MAC, and flexible protocols, do I need to authenticate the authentication?

Sorry, the question is not easy to state (or wasn't for me, anyhow). So I'm writing a very flexible format for security. It allows for full choice of cipher, key size, and so on, along with key ...
2
votes
2answers
92 views

Is this algorithm demonstrating “proof of work”

Is this algorithm demonstrating proof of work? This is a algorithm where a "token" is combined with a time stamp and then a cryptographic hash is generated from the combination, next the objective is ...
4
votes
3answers
179 views

Why can an RSA signature be authenticated ONLY with the signer's public key?

I'm an undergraduate Math student currently taking a cryptology course. I have a question about the RSA signature authentication mechanism. An RSA signature can be authenticated with the public key ...
0
votes
1answer
60 views

Authentication mechanism for low memory, low computing power device

I am looking for an authentication mechanism that works best with low memory, low computing power devices. I came across a paper "A Practical Zero-Knowledge Protocol Fitted to Security Microprocessor ...
8
votes
2answers
293 views

What current authenticated key exchange standards exist?

If neither of the 'big two' of TLS Handshake and IKE are appropriate in a given situation, what alternative Authenticated Key Exchange (AKE) standards exist and are recommended? Many protocols have ...
0
votes
0answers
38 views

Why doesn't this authentication protocol work? [duplicate]

I am a student taking a cryptography course so forgive me if this comes off as a silly question. This is an assignment question: Alice ------R--------> Bob Alice <-----[R]B------ Bob Alice ...
2
votes
1answer
95 views

Authentication of machine before installation (to stop piracy) [closed]

I have a web-software project which needs a bit of protection in form of authencitation… This web based software runs on an intranet. There is no access to the internet from these terminal machines. ...
1
vote
1answer
68 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 ...
0
votes
1answer
85 views

Biometric authentication [closed]

I see in some “Authentication schemes with biometric” papers that those authors wrote a phase as password and biometric update phase. My question is that why we may needs biometric update phase? Is ...
3
votes
1answer
370 views

OpenPGP/X.509 bridge: how to verify public key?

I'd like to use OpenPGP authentication over TLS, but lack of implementations made me use a temporary solution: an OpenPGP/X.509 bridge certificate. The approach is very similar to the approach used ...
3
votes
1answer
108 views

What security differences are there between E(p',“well-known-plaintext”) vs. hash(p') where p'=KDF(p)

I am using a KDF to derive a key, p' from a password p. I would like to know if the password is correct before using the derived ...
6
votes
1answer
123 views

Cryptography used for login and signing transactions

My bank uses a smartcard reader (separate module not connected to the computer) as depicted below: When I need to log into my account it provides me with a challenge and I need to provide some ...
13
votes
1answer
6k views

What are the differences between a digital signature, a MAC and a hash?

A message may be accompanied with a digital signature, a MAC or a message hash, as a proof of some kind. Which assurances does each primitive provide to the recipient? What kind of keys are needed?
4
votes
1answer
118 views

What authentication techniques can be used by QKD Systems?

As it is well known that QKD systems are prone to simple MITM attacks… what authentication techniques are being used in QKD to prevent those attacks in practice?
2
votes
1answer
111 views

Genuine encryption from only one source?

Is there any technique so that if I encrypt data, the ciphertext would be genuine and if someone else tries to encrypt the same data the ciphertext could be determined as fake or just invalid? I want ...
1
vote
2answers
101 views

Self authenticating tamper resistant first meetings

I'm not sure what the precise words I am looking for are so I apologize if there is a better way to phrase this. What I am thinking of is ways to transfer an identity in a way that it is tamper ...
2
votes
2answers
341 views

Please punch holes in this authentication scheme

Folks, I am undertaking a crypto course in Uni. Our professor asked us to try and design some authentication schemes which are resistant to active attacks. This was just a in class exercise to get us ...
1
vote
1answer
165 views

Verifying Self-signed SSL Client Certificates

I have a service and I want to authenticate my clients using SSL client certificates. Now I want the key exchange process to be as simple as possible, kind of like SSH: You generate a keypair and ...
3
votes
3answers
583 views

Is public-key cryptography the only option in this scenario?

Two parties: a client and a server are to a agree on a symmetric key. Both the client and the server are aware of a master password. The way this is currently done ...
2
votes
0answers
130 views

Integer factorization based password authentication

After looking at this security issue at DjangoProject, I started to think in a password-based authentication that places the burden of PBKDF2 (or whatever is the hashing function) on the client. So I ...
2
votes
2answers
177 views

Storing Credentials for a Third Party

(Originally posted to SOF, but I got no answers) I am designing a small application for use inside my company. My application needs to connect to a third party website on behalf of my application ...
5
votes
1answer
110 views

Authentication protocols for authenticating devices to a server

The requirement is to authenticate 1000s of devices to a server when the devices try to contact the server. The problem I face is that all authentication protocols require some kind of shared secret ...
4
votes
3answers
369 views

Convert old and busted password encryption to something sensible

Given a TOTALLY HYPOTHETICAL scenario in which passwords for over a million accounts in over 200 databases have been stored using 3DES, a key derived from a (single) MD5 hash of a customer-controlled ...
7
votes
3answers
303 views

Can one have an authentic, but repudiable, message without a previously shared secret?

Bob wants to send a message to Alice, such that Alice can be sure that the message came from Bob, but can't prove it to anyone else. If I understand right, this means that the same message could have ...
1
vote
2answers
172 views

What security flaw exists in MAC authentication scenario?

What security flaw exists (if any) in the solution of this non-encrypted authentication scenario? An unencrypted message passes one-way from computer A to B. Its transmission is viewable by the ...
1
vote
1answer
107 views

Can an encrypted nonce be used for authentication?

Would a scheme like the following work to allow authentication of a sender: A nonce is appended to data, and the result is encrypted. The encrypted pack is sent to the other party. The sender then ...
4
votes
1answer
288 views

Authenticated encryption mode for stream cipher?

E. g. block ciphers have GCM or OCB, that take single cryptographic primitive (block cipher) and provide both authentication and encryption. Are there similar constructs for stream ciphers, which ...
2
votes
3answers
436 views

Questions about BCrypt and PBKDF2

I would ask you some questions about users' password storage in a login system. What algorithm do you suggest me to use? bcrypt or PBKDF2? I was looking for a way to implement them client-side and ...
4
votes
2answers
514 views

How did LinkedIn “salt” all their passwords?

First, just to make sure I understand "salting" correctly: You randomly generate a string to append to the password before hashing it, so as to increase its length and make precomputed tables much ...
2
votes
1answer
133 views

Using plain Diffe-Hellman for server authentication with known public key

Other considerations aside, is it possible to use DH with an established public key (together with fixed g, p, q) to safely authenticate a server instead of using some signing algorithm? In other ...
2
votes
1answer
113 views

Offline app authentication - embedding hashed password inside an encrypted file

I am working on an occasionally connected app. To allow the users to authenticate I created a profile which is encrypted and placed on the users machine. The first byte of the file contains the IV ...
4
votes
1answer
298 views

Has GMAC mode a future outside GCM?

Once gcm has been implemented for providing both encryption & authentication solution , it appears obvious to consider that such implementation can also provide (if required by new user) a Mac ...
3
votes
1answer
434 views

Security of authenticated encryption modes gcm & ccm

I have two questions for Clarification for AE mode choice criteria GCM : it appears to be actually the most popular and widely used AE mode of operation. however it is also well-known to be highly ...
2
votes
2answers
111 views

KDF with low-entropy salts

I need to derive a key from a username and a password. These are the only two things I have access to. What I thought is using PBKDF2 with username as the salt and password as the master password. ...
2
votes
1answer
223 views

Is it considered insecure in an HOTP implementation to publicly provide the next counter?

I am working on a project that needs to securely authenticating one or more smartphone clients with a server running on a microcontroller so it has very limited resources. I have found plenty of ...
3
votes
1answer
256 views

Difference entity authentication and implicit key authentication

From the Handbook of Applied Cryptography, in discussions of key sharing algorithms, I see definitions: Implicit key authentication is when one party is assured that no other aside from a ...