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

2
votes
1answer
111 views

Message security and also program copy detection

Imagine I have client and server running on different machines, each as a separate software. I want to ensure: message authenticity, integrity and confidentiality at least of messages coming from ...
0
votes
1answer
94 views

Unconditionally Secure Authentication

I'm trying to add the authentication for my One-Time Pad implementation. I know that to provide Unconditionally Secure Authentication I need to use the One-Time MAC authentication. But I don't ...
2
votes
1answer
70 views

Implicit authentication aritcle

First, I want to know what is the logarithm used in the following system of equations (from the paper Flexible and Robust Privacy-Preserving Implicit Authentication - Domingo-Ferrer, Wu, Blanco-...
2
votes
1answer
118 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 ...
1
vote
0answers
33 views

cumulative secrets

Imagine a server with an authentication scheme that utilizes an element of randomness in new sessions (i.e. one that uses the secure remote password protocol). At the end of a successful ...
2
votes
1answer
58 views

Perfect Forward Secrecy in PGP/asynchronous email

Looking at the RFC for PGP email/asynchronous chat with PFS here https://tools.ietf.org/html/draft-brown-pgp-pfs-03 can anyone tell me why the following scheme is no good? Alice and Bob retrieve each ...
1
vote
1answer
81 views

Few questions about CBC MAC

I want to use CBC MAC. First I hope to find some implementation of block cipher which I will use in CBC mode, which I understand is CBC MAC. But I have two questions: 1) If the length of the message ...
2
votes
0answers
53 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 ...
2
votes
1answer
38 views

Should I authenticate memory data which was loaded from authenticated disk file?

Encrypted fields are loaded from disk file to process memory only after file's HMAC validation is successful. Data is still encrypted in memory and will be decrypted later, on demand, when it needs to ...
2
votes
0answers
39 views

David Chaum's anonymous credential

I am a newbie in cryptography (I know the basic RSA, AES stuffs) and am interested in anonymous authentication systems. Looks like David Chaum is the godly figure in the field. I see lots of people ...
2
votes
1answer
114 views

State of the art techniques for Anonymous Authentication?

What are the state of the art techniques for Anonymous Authentication? What are the most popular ones? The problem domain I am considering is with respect to different users accessing cloud content; ...
3
votes
1answer
78 views

Improving security of (authentication) protocol

I have a basic protocol which tries to authenticate messages going from client to server. Basically it is like this: Imagine I want to send message M to server. Client computes a MAC over the message....
0
votes
0answers
23 views

Advantages of the general digraph trust model over the strict hierarchical model

Are there any advantages of using reverse certificates and the general digraph trust model over the strict hierarchical trust model as described here: In the digraph model each CA can generate ...
5
votes
1answer
89 views

Do low-entropy fingerprints actually make any sense?

I'm thinking of ZRTP and OTR in particular here. From my understanding, after a Diffie-Hellman session is initiated, the shared secret is then hashed into a 4-digit number, which the two parties can ...
3
votes
0answers
66 views

Unknown authenticated encryption mode

I'm running through a protocol specification (LoRaWAN, pdf), and I'm puzzled by the crypto. The data is encrypted and authenticated in the following way: a unique 128-bit key is used; the plaintext ...
3
votes
1answer
131 views

(Lightweight) Multicast one-way Authentication

Problem: I'm thinking about a lightweight solution to provide source authentication (only one source) to multiple receivers (multicast message). Context: Taking the problem to ground, we can think ...
3
votes
2answers
62 views

Re-sending captured encrypted data

Let’s assume Bob is some algorithmic stock trading machine. Bob takes commands from Alice, who sends messages to Bob. For example: Alice could be sending a message to Bob to stop trading. But if ...
1
vote
0answers
45 views

Designing an AES-based protocol for controlling and acessing ioT boards via RF

I'm designing an open ioT protocol to be used on ioT boards based on Texas Instruments RF-based MCUs. These MCUs have an AES module to easily encrypt and decrypt AES content, so that's why I choose a ...
1
vote
1answer
76 views

Encrypt hash using hash of hash?

I wonder what is wrong with this scheme for authentication. Server sends random challenge, C Client returns (C, B(P)) encrypted in H(B(P)) where B(P) is high work factor salted hash of the user ...
3
votes
1answer
187 views

How can cryptographic signatures be somehow linked to a physical signature?

A few days ago, I was asked to sign an online document over DocuSign as well as on SignEasy, any the signature were accepted just by a physical signature sent over email or on the app. They did not ...
2
votes
2answers
75 views

Is it safe to use single-block AES for mutual authentication?

I read the question Symmetric mutual authentication with client using a derived secret and its answer which, if I'm not mistaken, assert that it should be safe to use the proposed protocol for mutual ...
1
vote
2answers
56 views

Are Anonymity and Authentication possible together?

Anonymity and authentication look to be seemingly contradictory but are both possible together ? I tried reading couple of papers but could not get the big picture. So what are the major approaches ...
1
vote
3answers
101 views

Cryptographically linkable random tokens

Are there any algorithms/protocols that let you produce a specific length of random tokens/bits in such a way that you can cryptographically determine which 2 or more tokens/bitstrings where produced ...
2
votes
2answers
223 views

Authenticating code securely and generating a certificate

I'm working on a product with strong security. Essentially there is an App, downloaded from the iTunes App Store. When the App starts up, it generates a strong RSA keypair and stores it in the ...
4
votes
2answers
47 views

Does SRP also authenticate the server to the client?

The Secure Remote Password (SRP) protocol lets a client prove to a server that it knows a specific password without revealing that password to the server. The server stores a cryptographic verifier ...
3
votes
3answers
101 views

Authenticate ephemeral key exchange

At the moment I'm designing a crytosystem for a VPN server. One of the requirements is Perfect Forward Secrecy, but I'n not sure how to implement authentication on the ephemeral key exchange. If both ...
5
votes
1answer
170 views

Fast 128-bit MAC with second preimage resistance?

I have an application that needs a fast 128-bit MAC to guarantee message authenticity in a protocol. I would like to reuse this MAC value as a binding identifier, so that even those who know the key ...
3
votes
2answers
315 views

Definition of authenticity

I came across various definitions of what authenticity means in cryptography. I would like to know which one is correct. The first definition - the one I always used - is the following: Data ...
2
votes
1answer
65 views

TLS Handshake : Server authentication or only Server ‘s Certificate authentication?

I have some difficulty understanding the way in which the Server is really authenticated by Client in TLS handshake (in case of using RSA key exchange). When Client receives Server ‘s Certificate and ...
1
vote
1answer
44 views

Authenticating with a document

Hope you're having a nice day. I need to implement an authentication system between a "document" (it's not exactly a document, but an object without any computing capacity, only able to store ...
2
votes
1answer
74 views

Can we use the authentication tag as Nonce / IV for the next message?

Let's assume we're in some scenario requiring transfer of large amounts of data. This means we can only use AES-GCM chunk-for-chunk as its maximal size is restricted to a few GiBs. This means we have ...
1
vote
1answer
132 views

Inverse public-key encryption

I'm in the need of an inverse public-key encryption method where you encrypt with the private key and decrypt with the public key. In other words an asymetric encryption where you can't generate the ...
2
votes
2answers
119 views

Client login without sending a password

I would love to have a system where the password is never send in plaintext (even with TLS) to authenticate a user. I've come up with this protocol, but I'd rather use something proven. Registration: ...
2
votes
1answer
96 views

How does the small n attack work?

I'm studying the Lamport's Hash one-time password scheme. This is the scheme: Alice wants to authenticate herself to Bob from a workstation that knows nothing about her. Alice only knows her ...
3
votes
1answer
226 views

public key cryptography and authentication for cross-platform network application

I'm developing network based application for control and telemetry on Linux based embedded system. I'm using ZMQ network library and Google Protocol Buffers serialization library for communication ...
1
vote
0answers
67 views

Understanding a faulty Needam-Schroeder protocol

Give this mutual-authentication protocol (along with the attack) in which Alice wants to communicate with Bob, I can't understand how the attack works. A chooses $N$ (nonce) and sends to C (trusted ...
4
votes
1answer
134 views

UKS attack on KEA protocol

I'm trying to understand the UKS attack on KEA protocol. This is described in this paper: Security Analysis of KEA Authenticated Key Exchange Protocol So to summarize: KEA protocol: UKS ...
5
votes
0answers
283 views

What is the original SKID3 protocol?

While searching for a mutual authentication protocol I often stumbled upon SKID3. However I encountered different variations of it. The basic structure is the following: (1) A --> B: rA (2) B --> A:...
3
votes
1answer
902 views

Authentication using AES

I need to implement an authentication mechanism in an embedded environment which does not support floating point operations but has an AES accelerator module which allows for encyption/decryption ...
4
votes
2answers
82 views

Is there a signature scheme for the Cramer-Shoup cryptosystem?

I have a project that I have to use cryptosystem and signature scheme for it. I've read about Cramer-Shoup cryptosystem and I want to use it since it is more secure the ElGamal cryptosystem, but, I ...
3
votes
1answer
128 views

How can I generate a good password from a SHA512 hash?

I have to change local administrator passwords on machines. I don't want to store password in a database. I have to generate a password that I can find later to connect to the machine again. So I ...
1
vote
1answer
147 views

MAC tag size in AES CCM, when using CTR + CBC-MAC (not CBC MAC only)

Assuming that AES CCM is used with respect of the NONCE unicity // the key life cycle, I wonder about the need of using the highest size for CBC-MAC authentication tag if CTR mode encrypts both ...
1
vote
1answer
64 views

Unconditional authentication

I have a few questions regarding universal-hash functions: Is there a way universal hash functions can be used to provide unconditional authentication in the way the OTP provides unconditional ...
2
votes
1answer
42 views

N users must approve a request

I have a locked-down production system that we'd like to process specific requests, picked-up (poll) from a less-secure location. For security and "go slow, this is production" reasons, a request ...
1
vote
0answers
81 views

How far is public-key crypto involved in “banking world”? [closed]

I would like to know how public key cryptography is used in the banking world. I am not looking for big details, but for example: Are banking card embedding a private key used for signing (...
4
votes
1answer
113 views

Parallel authentication of encrypted data. What AE type to choose?

I've got a system with a slow data transfer channel. Transferring a message through several channels does increase the transfer speed significatnly. AES-CBC+HMAC is good except that verifying the MAC ...
1
vote
2answers
94 views

Using password-based encryption as a hashing scheme

Classic scheme: Given password and hashing algorithm Generate salt Calculate ...
1
vote
1answer
163 views

What is a man-in-the-middle attack (for instance in Diffie-Hellman)?

I'm new to cryptography and I just started learning about the Diffie-Hellman key agreement. I read that this system is vulnerable to a man-in-the-middle attack when used alone. What kind of attack is ...
1
vote
1answer
532 views

Suggestion : CRC vs SHA1

I need some suggestions about the use of the CRC in my application. I need to be sure about the BIOS run by the CPU. I have a FPGA between the BIOS flash and the CPU that sniff every read performed by ...
1
vote
3answers
105 views

Is this client-side password hash scheme secure?

I want to build an app that uses client-side encryption for storing encrypted data on the server. A user-specific master key would be used, so to easily share it between devices a encrypted version of ...