# All Questions

806 views

### Is it possible to utilize an AES-128 encryption hardware unit for AES-256?

There exist processors (for example ARM v8/v9 archicteture based), which cannot do AES-256 hardware based, but are equipped with AES-128 encryption hardware units. Is it possible to utilize an ...
54 views

### Confusion on Private Information Retrieval by Keywords

PIR protocols retrieve an item from the database without the server knowing which item it is. But classic CPIR(Computational PIR) or IT-PIR (Information Theoretic PIR) protocols requires the user to ...
20 views

### Should we use exponent 3 in RSA-OAEP?

As I understand it the proof that RSA-OAEP is secure in the random oracle model is much tighter for exponent 3. Does that mean that exponent 3 should be chosen?
108 views

### Encrypt-then-HMAC implementation - am I doing it right?

I want to implement authenticated encryption using C#. There is a dot net class called encryptAndAuthenticate, but it is only supported on windows 8 or later, and I need the code to also work on ...
13 views

### Missing steps in McEliece example

This webpages gives an example of McEliece encryption. It's missing two steps. The first is how does the author get $\begin{bmatrix}1 & 1 & 1 & 0\end{bmatrix}^\intercal$ from ...
18 views

### McEliece variants that support signatures

Besides the Niederreiter cryptosystem, are there any other variants that support digital signatures? Can any of them sign arbitrary signatures unlike the Niederreiter cryptosystem? What are the key ...
18 views

### Determining the degree of freedom for a chi-squared test on a strict avalanche criterion matrix

I have read that the degree of freedom is calculated by subtracting 1 from the number of states a random variable can be in. I am performing a goodness of fit test on a 64*32 strict avalanche ...
42 views

### What would be a typical value for the security parameter of the Fully Homomorphic Encryption over the Integers scheme?

The parameters of the Fully Homomorphic Encryption scheme by Dijk et.al are chosen according to the value of the security parameter ${\lambda}$, section 3 of the aforementioned article. What is the ...
49 views

### File using same key on XOR cipher. Using CBC [closed]

I have some files that are encrypted using an unknown key and it's using the CBC method to encrypt the files. When I XOR two files together the first two bytes are always the same, but different for ...
97 views

### How secure is $\operatorname{AES256}_{\operatorname{ECB}}(\operatorname{ChaCha20}(\text{plaintext}))$?

Suppose I encrypt a bytestream using ChaCha20, and then encrypt the resulting ciphertext using AES in ECB mode. How secure is the combination?
13 views

### Why does HS1-SIV allow forgeries when the SIV collides, even when the PMN does not collide?

The HS1-SIV authors claim that forgeries are possible if an SIV collision occurs. However, I do not understand how this is possible unless the PMN collides too. Otherwise, the collision will be in ...
31 views

### Is parallel, vectorized NORX nearly as fast as hardware-accelerated AES-GCM?

As I understand it, NORX gets 3.5 CPB in an unoptimized implementation. But NORX can be parallelized. With 4-way SIMD, I would expect about 7/8 CPB performance. This is nearly as good as AES-GCM in ...
22 views

### Concatenated Key Question - Poly-alphabetic Substitution and Columnar Transposition

I am working on a degree module, and have been tasked with designing an Encryption/Decryption algorithm. I hope to receive some help with a couple of questions, if possible. Apologies if terminology ...
36 views

### RC6 Key Size Understanding

I need help to understand how RC6 works. Many sites show that the maximum key size of RC6 is 2040 bits (255 Bytes). I can also have 0..255 rounds and 4 times 32bits words in the 128bit block variant ...
34 views

### How to encrypt an image with logistic chaotic map?

I need to encrypt color images, using logistic chaotic map. Could you please recommend an algorithm for this? All the articles that I've found on the Internet are completely unclear.
19 views

### AES - Size of T-Boxes and obtaining T-Box values

In article "A high performance ST-Box based unified AES encryption/decryption architecture on FPGA" (http://www.sciencedirect.com/science/article/pii/S0141933115001945) two 32Kb dual-port BRAMs are ...
36 views

### Is pseudo-random letter insertion secure?

Is pseudo-random letter insertion a secure mechanism? I mean by expanding the key or taking two parameters in the encryption function, you select positions in the text at which to insert random ...
46 views

### Is there any IND-CPA secure stream cipher with a “standard” hardness assumption?

I've read our recent question: "One-time pad using RSA and Diffie-Hellman functions" which asks about the security of a particular way to convert RSA and discrete exponentiation into a stream cipher. ...
6 views

### the code generate error while using bouncycastleprovider [migrated]

I am trying to generate signature using ECDSA with binary curve (B163) . Also i am using Bouncy Castle libraries. but it generate error like this- Exception in thread "main" ...
26 views

### generate unpredictable value with a shared key

Is there any function that taek a key to generate (un)predictable value ? I hope you will more understand more what I mean with this example f take in input an array, a key and a round number ...
158 views

### What may be causing conflicts in Whirlpool implementation versions?

I see by layman articles (e.g. at Wikipedia) that the Whirlpool hash function has seemingly three current versions. That is to say, they are referenced as ...
79 views

18 views

### Is it okay to use Threefish-512 in ECB mode with Poly1305 MAC to protect some AES keys?

A person has some independent AES-GCM-SIV keys they need to protect as part of a hypothetical protocol or product, where it is publically known that it is in fact AES-GCM-SIV keys that are being ...
31 views

### Product of Vigenère ciphers is not a Vigenère cipher with length of LCM

I have always thought that using two Vigenère ciphers leads to another Vigenère cipher with key length of LCM (least common multiple) of the two previous Vigenère ciphers. But I have stumbled upon ...
193 views

### What is the difference between PBE and symmetric key encryption?

What is the difference between PBE (password based encryption) and symmetric-key algorithms? My understanding is that symmetric-key algorithms like AES and Twofish are used in PBE. Hence PBE is just ...
43 views

### Scalability of homomorphic tallying

Whenever I look at online voting schemes, the idea of homomorphic encryption being a key concept, specially in the form of homomorphic tallying, appears to be universally accepted. The accepted answer ...