# All Questions

186 views

### Why shouldn't I use ECB encryption?

I'm using Java to generate encrypted strings, and I get this warning at build time: ECB encryption mode should not be used So I'm wondering why I shouldn't use ECB and what I can use instead?
61 views

### Which multiplicatively homomorphic encryption scheme supports encryption of 0?

I want a multiplicatively homomorphic encryption scheme that supports encryption of 0 (e.g. Elgamal doesn't support). I also want the multiplication to be operated on the ciphertext of 0, i.e., if ...
91 views

### Which gives better deterministic encryption SIV or Plain ECB mode?

Lets say , if we encrypt a plain text message $msg$ with key $key$ in below two ways. Which is the below would give better deterministic encryption and why ? AES-ECB($key$ , $msg$) SIV($key$, NIL , ...
6 views

### Modifying message to use digital certificates

I have the following message: sign((M’, T$_A$, sign((encrypt((encrypt(M, $K_{pbB}$), M’), K), T$_B$), $K_{sB}$)), $K_{sA}$) How would i modify this message where a digital certificate is used by ...
72 views

### Polynomial division hardware implementation

I am beginning the implementation of the polynomial binary division algorithm now as I understood i will be checking the MSB bit if 1 to XOR and shift the sum if 0 i will only shift. What I am not ...
18 views

### Viability of an “Unconventional” Hashing Scheme?

I am playing around with the following hashing scheme: Start with a domain string (same for all users), Allow every user to mutate it in any way defining their own custom replacement rules, Append ...
4 views

### Specific example of a MAC in TLS?

This seems like quite a dumb question, but I really don't know if I'm finding a answer anywhere. I understand that if i access a website that is secured with TLS, we exchange ciphersuites and so on, ...
47 views

### Best hash-algorithm [on hold]

What is the most secure hash-algorithm. Can you also give the second best and the third best like this: 1. Test 2. test 3. TEST I dont care about the performance
52 views

### Find private exponent in RSA

The other answers for this confuse me, I know the principle of d in terms of the equation it has to satisfy. However I'm not sure how I would go about finding the private exponent without trial and ...
27 views

### How were shift amount constants in MD5 found?

The md5 specification gives a series of 4 rounds to execute over a 16-word block. Each round has a repeating sequence of 4 shift amounts (s in ...
816 views

### On-the-fly computation of AES Round Keys for decryption?

The usual implementation of AES first computes all the Round Keys sequentially starting from the key, and stores them in RAM for later uses. However, when enciphering a single block with a key that ...
435 views

### How Brittle Are LCG-Cracking Techniques?

There are published techniques for cracking LCGs, but to my eye those techniques seem very brittle — very minor changes can add nonlinearity that renders techniques like the LLL algorithm unusable. ...
52 views

### Alternative encryption algorithm

I need a alternative encryption alcorithm to AES. It shouldn't be AES, Twofish or Serpent and it must be very strong. I dont care about the performance.
29 views

### Probability of a bit changing SHA-1

I'm looking at diffusion (avalanche) in SHA-1, and how strong it is. I've seen on wikipedia that 'When a single bit is changed the hash sum becomes totally different.' ...
44 views

I figured that a really secure password would be an AES 128 key. If this key were to be base 64 encoded, I could replace 4 random bytes in it in order to make it unusable unless you know which bytes ...
7 views

### KPA on Feistel cipher?

I heard that DES is technically 'broken' because of attacks involving large amounts of known plaintext. These attacks are obviously academic and highly complicated, so for some intuition I was hoping ...
30 views

### Can a cryptosystem be unconditional secure if the same key $k \in \mathcal K$ is used for more than one encryption?

Can a cryptosystem be unconditional secure if the same key $k \in \mathcal K$ is used for more than one encryption ? I know that the one-time-pad doesn't have perfect secrecy and doesn't provide ...
49 views

### OpenSSL des-ede3 not producing same output as test vector implies it should be

I'm encrypting one of the standard TDEA/3DES/DES-EDE test vectors with openssl: ...
38 views

### What makes an algorithm “fast in software” vs. “fast in hardware”?

When reading about different algorithms, I often encounter claims that various algorithms are "fast in software" (e.g. Salsa20) or "fast in hardware" (e.g. DES). What properties make a cipher ...
24 views

### Does a cryptosystem provides unconditional security if and only if it provides perfect secrecy?

Is unconditional security and perfect secrecy one and the same thing, i.e a cryptosystem provides unconditional security if and only if it provides perfect secrecy ? I've wondered about the above and ...
13 views

### Client Emulation - Sending hexdump to server and getting response [on hold]

So I used wireshark to retrieve a hexdump that has been encrypted with RSA. I need to figure out what the response to that would be when it comes back from the server. How I imagine it would work ...
134 views