# All Questions

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### AES-GCM Hash sub key parameter in Intel's IPsec library

I am trying to use Intel's optimized AES-128-GCM implementation (from the Intel white paper “Fast Multi-buffer IPsec Implementations on Intel Architecture Processors”, you can find the code here). ...
66 views

### Is there a fast implementation of RSA for Microcontrollers?

Zhe Liu, Johann Großschädl, and Ilya Kizhvatov. "Efficient and Side-Channel Resistant RSA Implementation for 8-bit AVR Microcontrollers" describes a fast implementation, but only contains a sketch of ...
52 views

### Applying Vigenere on small strings with sorting capability

I am new to cryptography and have a question about a use of Vigenere cipher in the case of small strings. I'd like to encrypt keywords that are smaller than 10 characters. If I use Vigenere ...
33 views

### Clarification on the state of the art of qubit commitment

What is the current state of research on quibit commitment? It seems that the answer is not 2001 but it seems to me that a lot of these pdf are referring to a old protocols of quantum bit commitment ...
33 views

### cumulative secrets

Imagine a server with an authentication scheme that utilizes an element of randomness in new sessions (i.e. one that uses the secure remote password protocol). At the end of a successful ...
56 views

### key exchange using hashing with preshared secret

I came upon an idea the other day that I had some questions about. I am not a security professional but I do study with an amateur interest and have not heard of this particular idea before. There ...
23 views

### Does OEAP padding limit the size of my modulous to the size fo the hash function?

im looking at wiki at the moment as how to use oeap padding and it appears, help me out if im wrong as G(r) - expands r to the size of the padded message, I am then limited by the size of my hash ...
68 views

### Cryptographic operations for NISTP256 can be implemented using montgomery method?

I need to implement cryptographic operations starting with the curve NISTP256. I have been told to implement it using Montgomery method. I read a pfd from http://saluc.engr.uconn.edu/refs/sidechannel/...
32 views

### Edwards / Montgomery ECC over binary extension fields

I recentely had a discussion about the redesign of our ECC code for the library I'm collaborating on and the person I was discussing with came up with Edwards and Montgomery curves over binary ...
94 views

### Does the RSA algorithm use repeated squaring?

Simple question: in order to reduce such huge exponents in modular arithmetic, is repeated squaring used in RSA or is there a better way to implement it?
60 views

### How to check the signature without the predetermined function in ECDSA from openssl?

I'm developing a client for a two-factor authentication in Qt/C++ under openSUSE 13.2, 64bit. I've got the FIDO U2F Security Key from yubico/fido. I'm using the classes from openssl, in particular <...
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### Does CP-ABE have any disincentive to share secret keys

I want to use a CP-ABE scheme to encrypt data to be accessed by multiple unknown (at time of encryption) users. Reading the papers related to CP-ABE, there does not appear to be any disincentive for ...
39 views

### How to find the integer multiplicand from given two points?

I have two points on an elliptic curve $P(x_1,y_1)$ and $Q(x_2,y_2)$ and a scalar value $x$, where $P=x \cdot Q$. What is the best way that I could figure out the value of $x$? Given that I know all ...
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### Is this ECC based messaging method secure?

I developing an encrypted messaging for ZeroNet (aP2P file-based network, website: zeronet.io) and would like to have some guidelines if any of this could work. My first idea: In ZeroNet every user ...
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I've read the following paper and have one question on it. M. Luby and J. Staddon, "Combinatorial Bounds for Broadcast Encryption", EUROCRYPT'98. On page 523 (12th page of the paper) the authors say ...
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114 views

### Simplest way for strong cryptography in chat

I am a beginner in cryptography and I am interested for several weeks on this for my chat application. Basically, it is a centralized model. All messages are stored and potentially visible by ...
56 views

### equation of mixcolumn in the aes field

$c(y) = (03)y^3 + (01) y^2 + (01) y + (02)$ Let $d = (01)b$ in the AES field $GF(2^8)$. Provide exact equations for the bits $d_i, 0 \leq i \leq 7$, in terms of the bits $b_i$ of b. Can ...
122 views

### Obtain Enigma key having a encrypted text and the plain text

I have an Enigma message and I know what the original message is (a repetition of the same letter). Is it possible obtain the enigma key? I only know what kind of Enigma machine is it, but I need to ...
84 views

### What is the 'identity function' in AES?

I'm trying to understand how AES works. I got as far as knowing how a password is converted to an unifinished key with the PBKDF2 function. After that RFC3962 says that an AES useable key most be ...
50 views

### Designing an AES-based protocol for controlling and acessing ioT boards via RF

I'm designing an open ioT protocol to be used on ioT boards based on Texas Instruments RF-based MCUs. These MCUs have an AES module to easily encrypt and decrypt AES content, so that's why I choose a ...
562 views

### What is the most secure encryption algorithm to encrypt my password database?

The password manager I use lets me choose an algorithm from the list below in order to encrypt my password database: Microsoft Base Cryptographic Provider v1.0: RC2-128 RC4-128 DES-56 3DES TWO KEY-...
118 views

### Fingerprint RSA public key in PKCS1 format

I can't find anywhere details on how to fingerprint a public RSA key in PKCS1 format. There are a lot of examples on the internet on how to fingerprint an RSA public key in openssh format using ...
115 views

### Solving Vigenére with unknown alphabet

I'm trying to decrypt a cipher that I suppose has been encrypted with Vigenére. However I came about the following thought: The cipher consists of characters from [...
57 views

### Binary equation with encryption

I'm trying to test the ring signature scheme proposed by Rivest Shamir and Tauman in the famous paper "How to leak a secret". One of the step consist in 4) the signer solves the following ring ...
180 views

### Best way to implement secure client/server communication in Python

For a college programming assignment I have to implement a secure communication protocol between a server and one or more clients. Upon instantiation of the server program, a file is generated, call ...
45 views

### ABE Attributes Based Encryption

I have a question . How the system know the attributes of the users to be after that as a public key in ABE?
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### PKCS#11 Sessions

I am maintaining an application that uses PKCS#11 to talk to a smartcard. Somehow a session gets generated, but i cant figure out where in the code. I am using c# and the PKCS11Interop wrapper. The ...
36 views

### Is it possbile to get same set of public and private keys twice while creating CSR ? If so where does the conflict happens !?

I'm new to cryptography and please clarify if my below assumption is wrong. Lets assume, that two different banks creating CSR and they get identical public and private key pairs of RSA. In such ...
213 views

### Is there specific name for simple XOR with ADD/SUB encoding?

Several years ago a group of malware authors began using code like this: for (j = 0; j < length; j++) ptr[j] = (ptr[j] ^ VALUEA) - VALUEB; for encoding, and ...
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### Are there any existing ASN.1 structures for transferring symmetric keys?

Is there any reasonable ASN.1 standard to encode symmetric keys? I found PSKC, but it seems extremely heavy, and I can't quite find any library (e.g. bouncycastle) that would simplify using it. If ...
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### LFSR, different bits from different initial states

Suppose we useLFSR, which gives output $x_1x_2x_3\dots$ from some particular initial state. From another state, different from previous, same LSFR though, it gives sequence $y_1y_2y_3\dots$ ...
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### Symmetric stream cipher, is it known?

I am thinking on a simple symmetric stream cipher. My first idea is the following: The key is a set of array of random bytes ($\underline{k}_1$ ... $\underline{k}_n$), whose length is $l_1$, $l_2$, ....
34 views

### Where can I find a versatile PKI and library leveraging curve25519?

I note that Things that use Curve25519 provides a long list of protocols, software, and libraries that leverage curve25519, but I'm wondering if there is any such software that more fully implements a ...
22 views

### Is there a system where I can securely store a secret value and compare a semi-ambiguous input to it?

I have an idea for a new kind of mobile phone lock screen. When you first create your pattern, you put together a series of colors and compass directions from the following choices: Red, Blue, Yellow, ...
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### 2 round GOST_28147-89 cipher distinguisher

So, here is the scheme of how this will look graphically: The deal is to present distinguisher for this cipher. First of all here is my drafts: Way 1 Assume that distinguisher displays in ...
810 views

### Decrypt using OpenSSL produces packing errors

I am receiving an encrypted file and it's key from a partner. The Key has itself been encrypted using our Digital Certificate Public Key, though I don't know exactly how. The partner has instructed me ...
51 views

### What is the hardness in Decisional Linear Assumption (DLIN)?

I had understood what does the DLIN assumption means and here is a related question. But I fail to understand the 'real hardness' in this problem. I would be grateful if someone can help me to ...
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"Fully Homomorphic Encryption over the Integer" described a simple FHE scheme based on the GACD assumption. Its encryption function (on page 6) has the form $c \leftarrow (m + 2r + 2*\sum_{i \in S} ... 0answers 96 views ### CPA-security proof of “l-padded RSA” encryption scheme The 10.9 exercise from the Katz-Lindell textbook creates a lot of confusion, let me state it here. Consider the following experiment for an algorithm$A$and a function$l$with$l(n) \leq 2n-2\$ for ...

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