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
57 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
59 views

Using password-based encryption as a hashing scheme

Classic scheme: Given password and hashing algorithm Generate salt Calculate ...
1
vote
1answer
18 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
195 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
53 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 ...
3
votes
0answers
50 views

What is SRP-Z from?

The Stanford license for SRP says: Broader use of the SRP authentication technology, such as variants incorporating the use of an explicit server secret (SRP-Z), may require a license; yet ...
0
votes
0answers
32 views

Establish authentication

I have designed a basic authentication scheme where two nodes will mutually authenticate that other holds a shared secret. I have very limited RAM/ROM (its on uC) and bandwidth. Here it goes: ...
2
votes
1answer
39 views

Security of MSS

I have started reading about the Merkle Signature Scheme. I am a little confused about why it is believed to be secure against quantum attacks, couldn't the hash function be attacked? What would make ...
0
votes
2answers
34 views

Securely start a client server connection without ssl/tls [closed]

NOTE: Pardon my ignorance of encryption, I learned about these concepts today Going to rephrase this question, but I think I already have fine answers provided. I need to have a block of data ...
1
vote
1answer
26 views

On countermeasures for replay attacks. Does this one require plaint text password storage?

I was reading this wiki section on the countermeasures against replay attacks and it basically suggests that: If Bob wants to confirm Alice's identity he can send a one-time token (I think it should ...
0
votes
0answers
7 views

RPC Service Authentication using Server and Client Nonce [migrated]

Forgive my ignorance, security is not my field. I have a RPC server where the server keeps a protected file containing user names and corresponding passwords. I would like to securely authenticate ...
0
votes
1answer
139 views

Trying to understand the use of ECC in TLS certificates

I was looking the certificate of this website: https://www.cloudflare.com that has an ECC based certification. I'm just curious to know if is possible to understand which elliptic curve is used and ...
1
vote
2answers
53 views

Secure Channel - Encryption and Decryption Keys For A Message

I'm currently reading Cryptography Engineering and in Chapter 7, the topic of secure channel is discussed. The channel described is using CTR for encryption. Below I include images with pseudo-code ...
0
votes
0answers
121 views

My attempt of combining socialist millionaire and Diffie-Hellman. Is it any good?

I've come up with an algorithm to solve the socialist millionaire problem, but I'm not sure if the algorithm is secure. I wasn't able to find any flaw in it, but it seems too simple to be secure, so ...
2
votes
2answers
218 views

Why does TLS do Authenticate-then-Encrypt instead of Encrypt-then-Authenticate?

Encrypt-then-Authenticate (EtA) seems to generally be considered the better option, compared to Authenticate-then-Encrypt (AtE) (see this Crypto.SE question, for example). The people writing the RFC ...
0
votes
1answer
35 views

HTTPS and plaintext authentication

I have client connecting a server over HTTPS to send and retrieve data. The client always connects through HTTPS The certificate is known to the client beforehand (hard coded into the software) The ...
0
votes
1answer
55 views

What should I think about these unique certificate serial numbers [closed]

I was looking at the serial numbers of the certificates for www.google.com and wordpress.com. Wordpress was listed by openssl as: 04:0B:D4:F8:25:88:C5 This serial is listed as the serial for both ...
1
vote
1answer
34 views

Could this alternative hash based MAC construction be as, or even more secure than an HMAC?

Begin hashing (Key||Message) Encrypt the hash state (or some part of it, such as the first 128 or 256 bits), with the key. Add the encrypted hash state to the ...
6
votes
2answers
204 views

Is the HMAC construction really neccessary for a fixed length message?

The HMAC Construction is defined as: Hash( (Key XOR opad) || Hash((Key XOR ipad) || Message) ) This was designed because a simpler construction such as: ...
2
votes
0answers
29 views

Proposed unidirectional authentication scheme

I've been looking around for a way to authenticate a client to the server and deliver a message, but in a unidirectional fashion - that is, the client sends messages to the server, but the server ...
2
votes
1answer
78 views

Authenticate a short message with redundant encryption instead of using a MAC?

I have a short message that’s exactly 128 bits of length. The message serves as a time-limited authorization token for a database. It contains a permission profile ID (64 bits) and an issue timestamp ...
1
vote
1answer
137 views

Generate a list of valid ASCII codes

I have read many pages about encryption but I am really stuck on this. For access control to a building I want to print a 10 character ASCII code on a ticket (as a barcode). The barcode reader ...
4
votes
3answers
153 views

Why aren't zero-knowledge proofs used for authentication in practice?

I read on Wikipedia that zero-knowledge proofs are not used for authentication in practice. Instead (I think) the server is entrusted with seeing a password in plaintext form, which it should then add ...
2
votes
1answer
115 views

Is this variant of SRP useful?

I'm interested in using a modified form of SRP as a peer-to-peer authentication method. Since neither side is acting as a host, one of the primary design goals for SRP (that the client doesn't need ...
1
vote
1answer
58 views

Where is the authentication tag stored in file encrypted using AES-GCM?

So I am using cryptopp to encrypt a file in a project and I am using AES-GCM. I have a 256bit key and a 128bit ivec and a 128bit tag that I use to encrypt files. However, I want to know where the ...
0
votes
1answer
57 views

Which one these alternatives using authentication and encryption will solve this multiple-user database problem?

Which one these alternatives using authentication and encryption will solve this multiple-user database problem ? I'm trying to understand the field of cryptography, so I've started reading a ...
4
votes
1answer
218 views

The difference between MAC algorithms and what to use

I've been looking into message authentication codes and found several ways to create integrity for a message. I know of the following algorithms: HMAC, this can use any cryptograhpic hash function ...
1
vote
1answer
46 views

Is authentication length always a subset of encryption length?

Do in all the use cases, if I have to encrypt and authenticate, encrypt-then-authenticate or authenticate-then-encrypt, like in IPSEC, SSL or SSH or others, if I were to do these operations to a ...
0
votes
0answers
27 views

Does it make sense to have multiple values of authentication and cipher offsets while encrypting a packet?

Consider a packet with N segments. cofsset(cipher offset - from where one must cipher) lies in arbitrary Segment "A". aoffset (authentication offset - from where one must authenticate) lies in ...
0
votes
0answers
35 views

EC based password authenticated key exchange protocol

I would like to know: What is the currently best (efficiency and security wise) known EC based password authenticated key exchange protocol? (i.e. is there any EC based protocol may be similar to DH ...
0
votes
0answers
66 views

Popularity of ECMQV authenticated key agreement protocol

I've got a few ECMQV related questions: Why is ECMQV a more efficient EC-based authenticated key agreement protocol? Why is ECMQV so popular? Is it because no other protocol of its strength exists? ...
0
votes
1answer
60 views

Value of S and r in Fiat-Shamir Protocol

In the book Cryptography and Network Security by Forouzan,in chapter 14, Fiat-Shamir protocol, its mentioned that two large prime numbers p and q are chosen and kept secret. However n=p*q is made ...
1
vote
1answer
49 views

Replay Attack in Stream Cipher

Stream ciphers are vulnerable to replay attack if the same key k is used. If E() is a stream cipher and an attacker intercepts the message m that's being transmitted at time t, how can the attacker ...
2
votes
1answer
73 views

Is there an existing authorative definition of the cryptographic term 'pepper'

I can attempt to define the term 'pepper' as: In cryptography, a pepper is a something that is added to another value (for example a password) prior to a the value being hashed using a ...
2
votes
1answer
103 views

Is this a valid scheme to authenticate through a 'human-readable' certificate?

Let's say Alice wants to talk securely to Bob over the internet, and Eve is not only eavesdropping, but has managed to get into a MITM position. In this scheme Alice and Bob exchange $n$ (example $n ...
1
vote
1answer
70 views

Authentication using a one-time pad

I am building a small embedded system of two nodes that communicate wirelessly. The microcontrollers I'm using are very limited: they only have 256 bytes of RAM. I would like to be able to ...
0
votes
1answer
59 views

HMAC tag to verify the key (verification in the reverse direction)

A quick question. Are there any problems with the following HMAC use-case: We have two entities ($A$ and $B$), both of them have a secret ($A$ has $S_0$ and $B$ has $S_1$) $A$ generates a random ...
0
votes
0answers
82 views

Key exchange using hash function

Consider two types of attackers on a key exchange (KE) protocol and subsequent communication between the parties which used this KE instance to establish a secure communication key. Attacker Eve ...
0
votes
0answers
51 views

Attack on key exchange with authentication

Suppose the honest parties - Alice and Bob - exchange public key in person/via telephone so that attacker can only eavedrop on the line. Alice has hashed the public key using a collision resistance ...
0
votes
0answers
29 views

Transport SA bundled inside a tunnel with encryption applied before authentication?

For IPsec I am considering different formats of ESP encryption and authentication. I am not sure what happens with "Transport SA bundled inside a tunnel with encryption applied before ...
0
votes
0answers
57 views

What is the best authentication logic to analyze RFID (randomized hash-lock) authentication protocol?

What is the best authentication logic to analyze RFID (Randomized hash-lock) authentication protocol, (Ban logic, GNY logic, SVO logic, VO logic, AT logic) or another one?
2
votes
1answer
133 views

What is the advantage of using the socialist millionaire protocol to authenticate vs HMACing some random number?

Say Alice and Bob have a shared secret $s$. Alice and Bob establish an encrypted channel and verify that it hasn't been MitM'ed by exchanging $r_1$ and $r_2$, where $r_1$ and $r_2$ are randomly ...
0
votes
1answer
59 views

GCM implementation

I want to write GCM implementation myself (only for research purposes). So far, I have successfully written CTR implementation (for AES), but now I ran into few problems with GCM. If I'm not wrong, ...
0
votes
1answer
166 views

Symmetric mutual authentication with client using a derived secret

I'm attempting to find a client/server authentication protocol that allows the client and server to authenticate each other when the client doesn't know the server secret but does have a sensitive key ...
1
vote
1answer
214 views

CBC-MAC: is it secure to authenticate a fixed length ciphertext?

Suppose I have a fixed-length arbitrary ciphertext. To authenticate such ciphertext: I generate a random AES Key $K_{auth}$. Then I compute the CBC-MAC Tag of the ciphertext with $K_{auth}$. ...
1
vote
1answer
144 views

Additional Data in AEAD (Chacha20-poly1305 libsodium)

I have recently been playing with Chacha20-Poly1305 with libsodium, and all of the examples state the additional data portion of the tag is stored in plaintext when encrypted. But from what I can tell ...
0
votes
1answer
53 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 ...
1
vote
0answers
73 views

Performing HMAC with random key before MAC comparison

In Laravel (a PHP framework) I can see that they calculate a HMAC with a random key over the final HMAC before comparison. This additional HMAC calculation is of course performed for both the ...
2
votes
3answers
187 views

Key derivation of public key without knowledge of private key

I'm looking for a convenient way to share a set of public keys across multiple services, while preserving privacy by preventing these services from tying the identity of these public key sets together ...
0
votes
0answers
40 views

Modifying algebraic secrecy message to use digital certificates

I have the following message: sign((M’, T$_A$, sign((encrypt((encrypt(M, $K_{pbB}$), M’), K), T$_B$), $K_{sB}$)), $K_{sA}$) Sign is used for signature generation. Encrypt is used for ...