0
votes
0answers
8 views

Which is the most secure steganography technique?

Just like we have AES in crypotography, which is the most secure technique in Steganography? I am looking for a technique in which the standard image characteristic modifications it does go ...
1
vote
1answer
14 views

Can I reduce the MAC size in TLS?

The MAC size is reduced to 80 bits in truncated_hmac extension , which says "forging of MAC values cannot be done off-line: in TLS, a single failed MAC guess will cause the immediate termination of ...
1
vote
0answers
10 views

Software interface for KDF and PBKDF?

I'm working on an implementation of Krawczyk and Eronen HDKF from RFC 5869. From Krawczyk's original paper, he identifies four inputs to a KDF in Cryptographic Extraction and Key Derivation: The HKDF ...
2
votes
1answer
63 views

Differential Privacy and appropriate noise distribution

In differential privacy solutions and more specifically for queries that they do entail counting the proposed solutions define the Laplace distribution that is best calibrated for low error. Other ...
1
vote
1answer
185 views

How to prove Security of Onion Layers of encryption?

CryptDB has Onion layers of Encryption to provide wider functionality from weaker forms of encryption. How do we prove such things are indeed secure ? Intuitively It seems ok. Are there any parallels ...
0
votes
1answer
39 views

In what cases will RSA not work?

I know that there are cases when RSA will not work like when the number to feed into the system is greater than the modulus. I was wondering if there were any other cases when RSA won't work I looked ...
-1
votes
0answers
14 views

Philosophically elegant ways to implement a tabula recta

I'm working on a Python implementation of various classical crypto ciphers. I have various tabula recta ciphers: Vigenère, Beaufort, Variant Beaufort, Grönsfeld, Trithemius, Della Porta (not tabula ...
4
votes
0answers
76 views

Is there any practical attack to create a printable chosen prefix MD5 collision?

I would like to create two ASCII text messages with the same MD5. Is this possible? If not, is there a similar but less strict attack that could work? Or to rephrase my last question: what are the ...
0
votes
1answer
20 views

Standards to be a good cipher

I'm not sure I even understand this site, but based on what I see, how can one tell if a cipher is a good one-at what level is it considered good?
8
votes
6answers
262 views
+50

Mutual verification of shared secret

Is it possible to develop a scheme where two parties, unsure if they have the same secret, can verify that the other does or does not share the same secret, without one party being able to cheat and ...
0
votes
1answer
151 views

Problem with testing MD5 collisions

I am trying to test MD5 collisions presented in “Collisions for Hash Functions MD4, MD5, HAVA” (PDF) by Xiaoyun Wang, Dengguo Feng, Xuejia Lai, Hongbo Yu; 2004. I wrote a PHP script to test it, but ...
0
votes
0answers
14 views

How to choose McEliece's parameters?

At the time of this writing, there are 3 sources for parameters for the McEliece public-key cryptosystem out there. The first paper is the original McEliece paper, which only specifies ...
0
votes
2answers
46 views
0
votes
1answer
45 views

DSA: Authentication and assurance of authorized parties

When dealing with Asymmetric cryptographic algorithms, usually the sender of the critical data asks the listener for a Public Key for encrypting the data and sending them. This is while the private ...
1
vote
1answer
56 views

Key exchange using ECDH vs ECIES

I'm a beginner to ECC crypto programming. Does any one explain to me the difference with using ECDH for shared key exchange and use of ECIES by encrypting shared key with the public key of the ...
6
votes
3answers
367 views

1 Billion Bit Encryption?

So, browsing through YouTube, I stumbled on this video interview of John Draper (Captain Crunch), one of the first "hackers". He talks for about 3 minutes (until 27:48) about his home rolled ...
3
votes
0answers
47 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
11 views

Implementations of Adi Shamir's ID Based signature scheme [on hold]

Are there any open source or commercial distributions of Adi Shamir's ID based signature scheme? If yes, could you please point?
2
votes
2answers
76 views

Do all attacks against PKCS1 v1.5 encryption require an oracle

As far as I know, all attacks against RSA PKCS1 v1.5 require an oracle; is that true? Or are there any other attacks against it which are able to break it without an oracle? Background: I need to ...
0
votes
2answers
50 views

What are the advantages of using OFB (Output Feedback Mode)? [on hold]

I have a problem with OFB mode, because I have heard that it is stronger than CFB.
0
votes
1answer
65 views

Working on subgroup of $\mathbb{Z}^*_p$ in practice

It is said that, given a group $\mathbb{Z}^*_p$, we can always have a subgroup whose order is prime. To this end, for a safe prime $p=2q+1$, compute $x_i^2 \bmod p$ for all $x_i \in \mathbb{Z}^*_p$. ...
-1
votes
0answers
22 views

rngtest results interpretation [on hold]

With: rng-tools version 2-unofficial-mt.14-1 Tested this C++ code: ...
1
vote
2answers
51 views

Inner product with homomorphic encryption

I want to do a very simple thing: Given two vectors, I want to encrypt them and do some calculation, then decrypt the result and get the inner product between both vectors. Can you recommend me ...
0
votes
1answer
30 views

Question on Miller's algorithm (change the input m)

From the book titled " An Introduction to Mathematical Cryptography" (Chapter 5,page 322), we know that the miller's algorithm returns a function $f_P$ whose divisor satisfies $$div(f_P) ...
2
votes
1answer
45 views

Question about keyed hash functions

Maybe the answer to my question is obvious, but I have doubt... I have noticed that hash functions are studied in two forms, keyed hash functions or unkeyed. In general, lecture notes present hash ...
2
votes
2answers
688 views

I hashed my bag and in it I put… “Is there a hash for unordered items?”

(By items I mean hashable objects.) As an example (with obviously way too short hashes for readability), say I packed my bag and in it I put a shovel (hashed to ...
0
votes
1answer
77 views

Why is a Feistel network bijective?

EDIT: Fixed for clarity of intention I was reading "The FFX Mode of Operation for Format-Preserving Encryption" when I came across Figure 1 (see below). It's obvious why it's reversible (top-down ...
0
votes
1answer
132 views

security proof in pairing based cryptography

Let : $G_{0}$ and $G_{1}$ be two multiplicative cyclic groups of prime order $p$. $g$ is a generator of $G_{0}$ and $e$ is a bilinear map, $e : G0 × G0 → G1.$ $𝐶_{1} = 𝑔^{𝛽𝑠_{1}} $, $ 𝐶_{2} = ...
0
votes
1answer
70 views

Key Confirmation Attack [Key Distribution Center (KDC)]

Okay this is how I understood it according to this: Alice $A$ establishes a connection to $KDC$ and prepares for session key Exchange $k_{ses}$ $A$ encrypts the request with her key $k_A(A, B)$ ...
0
votes
2answers
179 views

Cryptosystems used to generate public key certificate

Where can we find the cryptosystems used to generate public key certificate? Are the cryptosystems under the signature algorithm and signature hash algorithm? Do I need to analyze the packets ...
2
votes
0answers
34 views

Logjam-style attack on Factoring?

We're all aware of the Logjam attack, which is known as "FREAK on discrete logarithms". Now the attack works by doing a large pre-computation step, which needs only to be done once per field and then ...
4
votes
1answer
49 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 ...
2
votes
1answer
30 views

Meaning of pseudocode “$(C, S):=$”

I've seen pseudocode of this form in the Montgomery Multiplication related theses: $(C, S) := a[j]*b[0]+C$. What's the meaning of "$(C, S):=$", or what is the real code that converted from this ...
2
votes
3answers
65 views

Reasons for components of AES

I started reading "Cryptography: theory and practice" by Stinson, and I am trying to understand the reason behind the choices for the different components of AES since they seem quite arbitrary. In ...
1
vote
1answer
30 views

What is the complexity for attacking 3DES in linear or differential cryptanalysis?

I know that 3DES is NOT vulnerable to DC , LC . But is it because the attacks requires too many input\output pairs ? Or because it's impossible ? (i.e requires more than 2^64 pair )
5
votes
2answers
130 views

Is standardizing a modified AES a good idea?

"Recently" the Ukraine standardized a new block cipher Kalyna, which according to the abstract of this paper (warning: the paper contains a lot of test-vectors) is basically a modified version of AES. ...
2
votes
0answers
50 views

Easy explanation of “IND-” security notions?

There are many schemes that can advertise themselves with certain security notions, usually IND-CPA or IND-CCA2, for example plain ElGamal has IND-CPA security but doesn't provide IND-CCA security. ...
1
vote
1answer
33 views

Does anyone still use BAN or GNY logic in practice?

I want to implement a simple protocol, and I'd like to verify it through BAN or GNY logic. I would assume that if these logics are still used that there would be some programs available that would ...
5
votes
4answers
2k views

Is a book cipher provably secure?

I've seen ciphers (usually in spy drama shows) that involve taking a book and writing down an index to individual characters. Essentially it's a keyed substitution cipher, where the key is the name ...
1
vote
1answer
34 views

Does XTS provide random write access?

I'm trying to find a sufficient encryption mode that supports random read and write access. It seems like XTS is a perfect fit, since in my use case authentication and integrity insurance are handled ...
6
votes
3answers
297 views

Can passwords be stored securely so that a similarity comparison can be made?

On the Pro Webmasters StackExchange site, someone asked a question about a webapp (in this case cPanel) that refused to allow a password change because it was too similar to a previous password. I ...
0
votes
1answer
52 views

The encryption scheme is secure?

I have a scheme and I don't know that this scheme is semantic security or not. -Secret keys $\{s_1,s_2, x_1,x_2\}$ and public parameter $p$ (large prime number) -Encryption E(m): $C_1 = s_1m + x_1k ...
1
vote
1answer
99 views
+50

How broken is a xor of two multiply with carry generators?

How broken is a xor of two LCGs? How Brittle Are LCG-Cracking Techniques? Based on the above two questions, I have simply one additional question: how broken is a XOR of two 64-bit multiply with ...
0
votes
0answers
20 views

RSA: If I sign the same digest with same key twice, will the signatures be identical? [duplicate]

If I don't have public keys to verify the signature, can I use this to discover that two signing services are using the same key? Can you send a reference?
1
vote
1answer
17 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 ...
0
votes
1answer
77 views

One-one correspondance complete function

I am reading the paper by John B. Kam and Georges I. Davida (1979) titled Structured Design of Substitution-Permutation Encryption Networks. On page 749 it reads ...
4
votes
1answer
194 views

Will hashing over and over eventually give the same hash?

There are many cases in maths where doing the same thing over and over again will bring you closer to a value. Derivation of polynomials is the striking example: no matter what you start with, you end ...
5
votes
2answers
270 views

Encryption of small messages

Some time ago, I asked how to encrypt small messages like e.g., four decimal digit numbers (banking PINs). I've got my answer, but also a warning like it makes no sense as it's easy to guess: Even ...
2
votes
1answer
32 views

Why should the input value on a DPA attack be non-constant?

I actually was wondering if anyone could help me out with the following problem: Let's assume we are attacking the first SubBytes() operation on AES with the help ...
1
vote
3answers
51 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 ...

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