4
votes
0answers
71 views

Missing public exponent

Using LUC RSA, I have a list of 8 public keys $(R_1,n_1)$ through $(R_8,n_8)$, and a list of $8$ messages $M_1\dots M_8$. The messages have all been double encrypted. However, one of the public key ...
4
votes
0answers
74 views

Is the reverse of the “discrete logarithm problem” equally dificult? [duplicate]

It is not easy to understand why this becomes a hard problem. The discrete logarithm problem as defined here: “any integer k that solves $b^k = \{g\mod{n}\}$ is termed a discrete logarithm” i.e.: ...
4
votes
0answers
100 views

Under what conditions did a Bletchley bombe stop?

I am trying to understand the conditions necessary for one of the Bletchley Park bombes to stop. Let me give an example. I have been experimenting with Enigma machine and bombe simulators to try to ...
4
votes
0answers
278 views

Looking for C++/Python Open Source code library for cryptanalysis of classical ciphers [closed]

I've done a significant amount of coding over the years working on classical ciphers (e.g., Chaocipher, D'Agapeyeff). My main programming languages today are C++ and Python, although there was a time ...
4
votes
0answers
129 views

Statistical saturation attack on block ciphers

I was wondering if anyone around here could give me some explanation on this type of attacks. Pretty much the only thing that I could find is A Statistical Saturation Attack against the Block Cipher ...
4
votes
0answers
70 views

Are there any asymmetric composite order group bilinear pairings?

Are there any asymmetric composite order group bilinear pairings? Is there a drawback of asymmetric over symmetric bilinear pairings of composite order either in efficiency or in security ?
4
votes
0answers
95 views

Anonymisation resilient to key leak

Problem statement Elbonian citizens have been issued a card holding a random $B_j\in\{0,1\}^b$, $0\le j<2^n$, $b\ge n+20$ (representative example $b=64$, $n=28$). The habit has grown to use this ...
4
votes
0answers
304 views

Evaluating Algebraic Complexity of a S-box

While studying the design and the desirable properties of an AES S-box , I came to know that Algebraic Complexity is also an important property of an S-box which is usually considered while evaluating ...
4
votes
0answers
128 views

What are the current limitations (and capabilities) of Functional Encryption used for access control?

I'm trying to make my way in Functional Encryption used for access control. I read a lot of papers such as "How to Run Turing Machines on Encrypted Data", "Functional Encryption: New Perspectives and ...
4
votes
1answer
178 views

Is it safe to derive a password from a signature provided by ssh-agent?

I'd like to use a password-based system on a remote host (accessed via SSH) without having to copy-and-paste the password and without storing it on disk. Using the system with some other form of ...
4
votes
1answer
118 views

Implementing the Mceliece Encryption - making the Generator Matrix

I am working on an implementation of the Mceliece Encryption system (MCE) and the Niederreiter encryption system. I have been through the basics of finite fields, polynomial arithmetic and some coding ...
4
votes
0answers
146 views

understanding the proof of knowledge

Recently I've been reading the paper “A New Family of Implicitly Authenticated Diffie-Hellman Protocols”. It's very hard for me to go further. Especially when it comes to the proof of knowledge. ...
4
votes
0answers
76 views

Feasible way to check n-dimensional equidistribution of PRNGs

I am currently gathering some test methods and test suites for random number generator qualities, and am a bit stuck at finding something feasible to test for n-dimensional equidistribution. As input ...
4
votes
0answers
227 views

Is there a flaw in this ECC blind signature scheme?

Recently I've found the following work on the internet: An ECC-Based Blind Signature Scheme The paper claims to be an ECDSA blind signature however it seems that their scheme has a flaw in it. The ...
4
votes
0answers
202 views

Using the same private key for two ECC key pairs

Let $(d_1,Q_1)$ and $(d_2,Q_2)$ be ECC key pairs over two different elliptic curves (say NIST P-224 and NIST P-256). According to the Elliptic Curve Discrete Logarithm Problem (ECDLP), if the private ...
4
votes
0answers
94 views

How has the “power” of cryptography evolved from its beginnings till today? [closed]

I'm looking for a historical overview for the change in cryptographic power, which I hereby define as How far state-of-the-art cryptography is ahead of state-of-the-art cryptanalysis. In other ...
4
votes
0answers
102 views

What informal indicators exist for estimating the computational infeasibility of cryptographic problems?

When assuming a block cipher primitive is secure, or a number theoretic problem is hard, this assumption is usually based on how far we are from breaking the primitive or solving the problem using ...
4
votes
0answers
309 views

Is there a “brainwallet” for GPG keys? [closed]

“Brainwallet” is a program that takes a passphrase (hopefully a good one) and deterministically creates a Bitcoin wallet. This wallet can be used for transactions, then deleted from the computer. To ...
4
votes
1answer
301 views

Complexity class of an idealised version of Bitcoin's proof-of-work (hashcash)? [closed]

To formulate this question precisely, I will define an idealized hypothetical "perfect" hash function $H(n)$ which has nice scalability properties, and will formulate a problem PERFECT HASHCASH in ...
4
votes
0answers
987 views

Reasons for Chinese SM2 Digital Signature Algorithm

In the IETF RFC draft named "SM2 Digital Signature Algorithm" a signature algorithm is specified. The RFC does however not mention why this signature algorithm has been defined. Nor does it specify ...
4
votes
0answers
61 views

CBC with random prefix but no IV - secure? [duplicate]

I'm looking at a datagram-based protocol that encrypts a payload. The payload is encrypted with AES or blowfish in CBC mode, and the result is then authenticated with a HMAC. To save space, the ...
4
votes
2answers
348 views

AES-CTR with ephemeral keys vs IV

Let's say that we have a key exchange of some sort, which leaves A and B sharing the long-term secret $S$. Then, A and B want to use AES-CTR for the communication, which leaves us with several ...
4
votes
0answers
162 views

Unique GCM/CCM initial counters without recipient side message counters

I am implementing the encryption layer for a communication protocol. The bulk encryption method used is either AES-CCM or AES-GCM. Due to implementation details, encryption of packets is usually, but ...
4
votes
0answers
92 views

Is SHA-1 collision free on data up to 20 bytes long? [duplicate]

Is SHA-1 collision free on data up to 20 bytes long (lenght of hash / internal state)? That means that every input produce unique output, but you surely know that, i just write it in order my question ...
4
votes
0answers
177 views

Does Keccak have an eTCR mode?

On page 7 of NIST's views on SHA-3's security requirements and Evaluation of attacks, I see that, at least at this point, NIST planned on offering SHA-3 having eTCR security (defined on page 3): ...
4
votes
0answers
191 views

Ring Signature - paper/code difference in trying to solve inverse trap door function?

there is a paper on ring signatures and a python implementation of it here. The Step 4 in the paper describes $y_s = v =C_k,_v(y_1, y_2, ... y_r)$ for all $1 \leq i \leq r$ where $i \neq s$. The ...
4
votes
0answers
121 views

RSA security assumptions - does breaking the DLP also break RSA? [duplicate]

Possible Duplicate: Would the ability to efficiently find Discrete Logs have any impact on the security of RSA? I'm wondering if breaking the DLP, that is the basis for ElGamal and DSA, ...
4
votes
2answers
190 views

Alternative sources of random numbers

Considering that algorithmic methods for generating unpredictable streams are hard to come by, I've wondered if any of these potential sources are good for making keys, seeds, and the like: stocks, ...
3
votes
2answers
1k views

Generate RSA-2048 private key for a VERY fast decryption (don't care if it will be unsecure)

Given public standard RSA exponent e = 65537, is there any (d, n) pairs so that RSA decryption becomes a trivial operation? The modulus n must be no less than 2048-bit. The goal is to get a real ...
3
votes
4answers
699 views

Do any non-US ciphers exist?

Plenty of ciphers come out of the USA from government research or selection competitions. AES and DES are examples. Are there any public ciphers produced by other states, China or Iran for example? ...
3
votes
5answers
2k views

Using one-way hash functions as the encryption method

Suppose two parties want to communicate securely with each other (Bob and Alice) using a simple messaging system in English. There are approximately 180,000 currently used words in the English ...
3
votes
3answers
610 views

How to submit a new method of encryption?

I came up with a truly new method of applying modulo-2-addition encryption function in stream ciphers which is inspired by a mechanism used to prove a mathematical theorem. How can I determine whether ...
3
votes
1answer
576 views

Why does “2xAES-256” provide “99.99%” security strength whereas “1xAES-128” provides “40%”? [closed]

I recently was "directed" to FlipsCloud, a company selling security solutions (as far as I can tell). In particular I've investigated their page and found a page on their "encryption features". This ...
3
votes
3answers
726 views

Implementing a one-time pad without binary?

This is a program that I found which takes a purely alphabetical message, converts the letters to their ASCII values and combines them with the ASCII values of an alphabetical key (wrapping around ...
3
votes
5answers
2k views

Approach towards anonymous e-voting

I want to implement an internet-based e-voting system. Voters shall be able to cast their vote for one out of n possible candidates. Each candidate has his own ballot-box kept by and at a trustworthy ...
3
votes
2answers
649 views

security of Felix cipher

I just find this pencil and paper cipher 'Felix' and I want to know how secure it is? EDIT From http://web.archive.org/web/20110825142054/http://topcat.hypermart.net/papers/felix.txt Felix a ...
3
votes
3answers
929 views

Complexity of arithmetic in a finite field?

I am wondering what the complexities are of adding/subtracting and muliplying/dividing numbers in a finite field $\mathbb{F}_q$. I need it to understand an article I am reading. Thank you
3
votes
1answer
606 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 ...
3
votes
2answers
460 views

AES-ECB as an authentication mechanism

ECB is considered to be insecure when used for confidentiality because identical plaintext result with identical ciphertext. But what if we use ECB for authentication? Assume A wants to transmit an ...
3
votes
3answers
3k views

How to use HMAC-SHA1, HMAC-SHA2 in conjunction with AES

I understand how to compute HMAC-SHA1, HMAC-SHA2 etcetera. Please explain why/how is the resulting HMAC value is used in conjunction with AES for encryption/decryption and signing/verifying. In ...
3
votes
2answers
318 views

If Bob steals Alice's private key, how exactly would he read her encrypted documents?

So Bob grabs Alice's secret key when she isn't looking and her encrypted files, doesn't he need to know her passphrase to read her files? What I am reading is that no he does not need it but as far ...
3
votes
3answers
247 views

For AES CBC, can I encrypt the IV with AES ECB and the same key and include it with the message?

Is it safe to use this process: Generate Key, IV Encrypt Message with Key, IV and AES CBC into EMessage Encrypt IV with ECB into EIV Send over EIV + EMessage Then the recipient Decrypt EIV with ...
3
votes
5answers
2k views

Why is the private key generated first in public key crypto?

I'm still new to public key crypto. I'm trying to understand how it is that the private key is generated first in public key crypto? I would have expected the private and public key to be generated at ...
3
votes
2answers
5k views

What characters does AES output?

From what I understand after testing the Crypto-JS file here: http://crypto-js.googlecode.com/svn/tags/3.1.2/build/rollups/aes.js AES creates encrypted strings that contained letters, both ...
3
votes
4answers
533 views

Verify product without revealing multipliers

Situation: Several participants contribute encrypted random numbers. These numbers will be used to generate community-agreed random (by simple multiplication). Question: Is there any way to detect ...
3
votes
2answers
999 views

breaking fully homomorphic encryption schemes

Fully homomorphic encryption schemes allow one to evaluate any arbitrary computation over encrypted data. Intuitively this seems to be too weak, irrespective of how we achieve this. An adversary who ...
3
votes
3answers
450 views

Advantages of 64-bit CPU smartphone

Advantages of having a 64-bit CPU vs 32-Bit CPU smartphone … 3. Complex Encryption. Improved Security: 64-Bit can process incredibly large numbers allowing you to better encrypt data against ...
3
votes
4answers
3k views

Initialization vector in symmetric-key encryption

Can we use symmetric-key algorithms without an initialization vector? I am making an app where both the sender and receiver share a key and there is no way to create an initialization vector for each ...
3
votes
3answers
356 views

Is it possible to work out the hash algorithm from a list of known message-hash pairs?

For example, in my situation I know hash(20) = 486e9638177faf1f34e49910491b77af. I also know the hashes for all values from 0 to 20. Is it possible to work out the ...
3
votes
3answers
13k views

Where i can find an AES implementation in python?

Where i can find a "reviewed" version of AES implementation in python. Not an API like PyCrypto whereby you can call AES algorithms in a single line.

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