-1
votes
1answer
160 views

Same Size Crypto Algorithm?

I need to know there is any algorithm that crypts data in same size, Any knowledge appriciated! Thank you!
-1
votes
1answer
609 views

Is it possible to crack a blowfish 256 bits encrypted file? [closed]

I have a file of my own that I have encrypted using Coder-Abi. Now, I can just remember part of this password. So, would it be possible (much easier) for me to crack it knowing only part of it? I can ...
-1
votes
1answer
184 views

Because the algorithm is known, it is no longer a trade secret [closed]

In wiki about RC4 cipher they said, Because the algorithm is known, it is no longer a trade secret. Is that mean the cipher text will be more secure if the algorithm unknown to the attacker. ...
-1
votes
1answer
264 views

Matrix Multiplication of Bits

How to multiply the matrix of bits example I have two 4x4 matrices of bits ...
-1
votes
1answer
11k views

Uncompress the winRar password protected file without password. (not brute force attacking)

I would like to know how to extract contents of the password protected winrar file without the password. I have downloaded that WinRar file from a file hosting website. I only found out that it was ...
-1
votes
2answers
162 views

What is the advantage of an attacker over breaking a 4 digits PIN?

When a hardware system is protected by a 4 digits password, what is the advantage of the attacker into breaking that system? Isn't it $10*10*10*10=10^{4}$? If $\frac{1}{10^{4}}$ is the cost of such ...
-1
votes
2answers
28 views

How to make sure the pre-agreed information safe for DH-Key Exchange

The definition of DH key exchange was given as the method let two authenticate each other & exchange the crypto key over an insecure channel. DH-key-exchange was innovated to defence ...
-1
votes
1answer
55 views

How do they implement MAC in TLS?

I recently read questions about "MAC then Encrypt/Encrypt then MAC" which made me curious about how they actually use the algorithm. MAC only calculated once either case (according to what I read). ...
-1
votes
1answer
90 views

cryptography and use of python programming language [closed]

why is it recommended to write cryptography programs ,for example crypt-analysis projects with python programming language? what is the advantages of python? why not use c or any other language?
-1
votes
1answer
41 views

What's wrong with this “order-preserving MAC” function?

Please note: this is purely a thought experiment and not intended for any real-world usage! I came up with a simple function $\mathrm{OPF}$ to map the integers $[0,C)$ (where $C$ is the "ChunkSize") ...
-1
votes
1answer
46 views

AES CBC MAC splicing attack

I'm trying to implement AES CBC MAC splicing attack in Python, the idea is: given a message M, its tag Tm (MAC(M) = T), a new message N and its tag Tn we build a message such as: M||N = (M1, ..., Mn, ...
-1
votes
1answer
30 views

In Needham Schroeder key distribution what happens if responder's part is not encrypted in step 2 with Kbs but encrypted instead by Kab in step 3

The Needham-Schroeder protocol is: 1 A→S:A,B,Na 2 S→A:{Na,B,Kab,{Kab,A}Kbs}Kas 3 A→B:{Kab,A}Kbs 4 B→A:{Nb}Kab 5 A→B:{Nb−1}Kab Here Na and Nb are nonces. Kab is the key between a and b Kas is ...
-1
votes
1answer
89 views

Hash Based Encryption (fast & simple), how well would this compare to AES? [duplicate]

First of all, I know it's a very bad idea to invent your own encryption algorithm. It's better to use existing known, trusted, extensively tested and studied algorithms with a proven track record. The ...
-1
votes
1answer
32 views

Affine encryption function

Let $f(x) = ax + b$ be an affine encryption function. $a$ and the cardinal of the field of our keys $K$ (in English, 26) must be coprime so that the encryption ...
-1
votes
1answer
74 views

Hypothetical question about AES output

Consider that you stumble upon 5 different AES output strings. One of these strings can be decrypted with a secret phrase, the other four strings are based on the real string but have had random parts ...
-1
votes
1answer
76 views

Assuming that we had a way of finding primes, could RSA be used without computers?

I once asked a question "Would RSA make sense if we used no computers?". The answer was negative, because finding primes that would make secure keys would prove too hard. Assuming that we had found ...
-1
votes
1answer
95 views

Why is it said that if we know few bits of pseudo random sequence we can predict the whole of it?

I am new to this cryptography and in the source from which i study it is said that if we know the first few bits of a pseudo random sequence we can predict the whole of it.How is it possible? The ...
-1
votes
2answers
579 views

How does the rand() function in C work? [closed]

I want to know how rand() works (even when I don't provide any seed how it produces PRNs?) thanks!
-1
votes
2answers
198 views

What are alternatives to the random oracle model for modelling hash functions? [closed]

I was looking for more realistic alternatives to the ROM for describing hash functions in theoretical proofs. I came across the common reference string model (where hash functions can be modeled as ...
-1
votes
1answer
107 views

Cryptographic Primitive Method

Is there any cryptographic primitive bijective (one-to-one and onto) function for creating cryptographic tools like symmetric encryption/decryption, Hash code generator, MAC, HMAC and Random number ...
-1
votes
1answer
44 views

Positioning of keys in encrypted text

I'm just looking at very simple encryption. I've noticed that the key is typically either at the front or at the back of the encrypted text. This is quite easy to break if you know the key. It can ...
-1
votes
1answer
55 views

encrypting data signals using the time variations between two independent coupling functions [closed]

There was a recent article about a new encryption technique that encrypts "using the time variations between two independent coupling functions". What is this technique they are referring to?
-1
votes
1answer
41 views

How to create PSK key? [closed]

I'd like to create a PSK key to use with TLS-RSA-PSK-WITH-AES-256-CBC-SHA - what is the format of this key?
-1
votes
1answer
95 views

Hash Based Encryption (fast & simple), how well would this compare to AES? [duplicate]

First of all, I know it's a very bad idea to invent your own encryption algorithm. It's better to use existing known, trusted, extensively tested and studied algorithms with a proven track record. The ...
-1
votes
1answer
64 views

Number of possible keys in a Play fair cipher [duplicate]

So for the play fair case, the number of possible keys is : 26x26 = 676 possible keys But if we consider the repeated letters, how many unique keys will the play fair have? I mean how will ...
-1
votes
1answer
48 views

Adding “salt” to “doHash” function in Java [closed]

For one of my university projects I am being asked to "Improve the code to satisfy the pre-image resistance requirement." Basically the program is a basic encryption server system, and when I type a ...
-1
votes
2answers
88 views

Need Help Reversing my Encryption Algorithm [closed]

So I wrote a simple encryption algorithm (Not very secure, just a starting point. I don't want criticism on it.) and I have been having trouble finding a way to decrypt the text. The algorithm is here ...
-1
votes
1answer
88 views

Can someone explain how this unpadded RSA formula works?

Taken from http://en.wikipedia.org/wiki/Homomorphic_encryption, $\mathcal{E}(x_1) \cdot \mathcal{E}(x_2) = x_1^e x_2^e$ $\bmod\; m = (x_1x_2)^e \;$ $\bmod\; m = \mathcal{E}(x_1 \cdot x_2)$ What is ...
-1
votes
1answer
69 views

Is size Q equal to size SHA(Q)? [closed]

Assume d is a 128 bit random integer and P is base point of an elliptic curve and Q = dP is a point on the elliptic curve and SHA is a hash function with 128 bit output, my question is: Is size Q ...
-1
votes
1answer
77 views

what is pairing in cryptography? [closed]

Let $G_1, G_2$ be additive groups and $G_T$ a multiplicative group, all of prime order $p$. Let $P $ in $G_1, Q $ in $G_2$ be generators of $G_1$ and $G_2$ respectively. A pairing is a map: $e:( ...
-1
votes
1answer
548 views

AES: keylength and password length? [closed]

What is the difference between the keylength and the length of a password for AES-256?
-1
votes
1answer
120 views

Integer factorization via geometric mean problem

presume: we have A and B integers, and C - product of multiplication of A and B, A and B are prime numbers (strong or usual) G - is geometric mean of A and B (square root of C) also, we have: if B > ...
-1
votes
1answer
115 views

Trying to finalize my understanding about password storing

am sorry, an a beginner, so please forgive me if i make mistakes, so here is what I understood: PBKDF2: uses HMAC, so, the message is the password, and the key that crypts the message is the salt? or ...
-1
votes
2answers
256 views

Is triple des similiar to RSA in that they message size is limited to the key size?

Is triple des similiar to rsa in that the message size you can encrypt is limited (unlike AES)? Yes you can break the message size into parts and apply it, but I'm not interested in doing that so I ...
-1
votes
1answer
519 views

University for Crypto grad study [closed]

(I thought twice before asking this question and quite reluctant to type as well, but I think this would be helpful). I am an undergrad student and choose theoretical computer science as my major. ...
-1
votes
2answers
73 views

Book Didactic Security Notions [closed]

I want study more about cryptography reading papers, but I have a problems to understand few concepts: security notions, random oracle model, IND-CCA, ... etc. I began study this concepts by internet: ...
-1
votes
1answer
615 views

How to hack the new save encryption on ipad for uplink? [closed]

The new iPad version of Uplink appears to be using some newer saving mechanic than the PC/Mac version. Macs and PCs use the REDSHIRT format, but the iPad appears to instead be using ...
-1
votes
1answer
322 views

File Encryption/Decryption in ECB mode [duplicate]

Possible Duplicate: Removing Padded Value in Decrypted Message I tried to encrypt and decrypt a file in ECB mode using AES Algorithm but I encountered one problem during decryption, I don't ...
-1
votes
1answer
705 views

Cryptography for kids [closed]

My daughter has been playing on the NSA's web page called CryptoKids but I was wondering if there is anything else out there that is may be more challenging to a nine year old. Books are good, ...
-1
votes
1answer
120 views

amateur cryptosystem -> a very long boolean expression -> attempt to reduce it [closed]

(newbie here) I try to analyze amateur cryptosystem and wondering, if it's possible to reduce it as reduce a very long boolean expression? What tool can I try to use?
-1
votes
1answer
175 views

How can we find Public key have only 8 or 16bits? How many messages does Eve need to know the Public key in RSA?

Suppose Alice sends messages to Bob by encrypting the messages with Bob's public key. Eve knows that the data is encrypted using RSA, but does not know the public key. Can Eve figure out the public ...
-1
votes
1answer
735 views

What are open problems in cryptography? [closed]

I would be starting groundwork for my thesis in cryptography , I would like to know what are current open problems in cryptography, few I know of are Fully Homomorphic Encryption Functional ...
-1
votes
1answer
178 views

How to control the output of a hash function to output to specific data according to similarity?

I do not know if the question lies exactly in that field but i'll give it a try unless rejection. I want to study methods of applying LSH functions to feet in a specific area of digest values. Briefly ...
-1
votes
0answers
37 views

mathematical derivation for elliptic curve cryptography [on hold]

how to derive the mathematical derivation for elliptic curve cryptography,please to send full detail derivation for elliptic curve cryptography,and also i need how to use the galois field in ...
-1
votes
0answers
38 views

Which commitment scheme is better for malicious models [on hold]

Can some one suggest which scheme is better for malicious models in terms of efficiency and security? A Pedersen's VSS based scheme or the one based on Fiat-Feige-Shamir digital signatures ?
-1
votes
0answers
51 views

What is the asymptotic complexity of RSA and paillier cryptosystem algorithm? [closed]

I want to know the complexity of the RSA and paillier cryptosystem algorithm in asymptotic notation.
-1
votes
0answers
28 views

HKDF as keystream generator

This is not my design, but used in the onepw protocol used for the new sync scheme in firefox by mozilla. https://github.com/mozilla/fxa-auth-server/wiki/onepw-protocol In this scheme a key is ...
-1
votes
0answers
46 views

Adequate DH secret size [duplicate]

What's the adequate secret size for Diffie-Hellman when using a 2048 bits safe prime as modp value? KeyLength.com recommends 224 bit but I don't understand a thing: if the security is "bounded" by the ...
-1
votes
0answers
38 views

What are the exact steps to decryption in International data Encryption Algorithm (IDEA)?

Can anyone tell me what are the exact steps for decryption in IDEA algorithm? I am doing that in this way: Taking multiplicative and additive inverse modulo of encryption keys. Creating decryption ...
-1
votes
0answers
26 views

Is it possible to find an attack that can reduce the key space of the Hill cipher with $d*d$ key matrix to $26^d$ [duplicate]

Is it possible to find an attack that can reduce the key space of the Hill cipher with $d*d$ key matrix to $26^d$ instead of $26^{d^2}$?

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