# All Questions

118 views

### Is signing a plaintext sufficient?

If I have N bytes of plaintext, does signing it with my private key prove (to holders of my public key) that I have signed that exact plaintext messages? i.e. could an attacker use the plaintext and ...
I want to implement the ATV-FHE scheme as it is described here https://eprint.iacr.org/2014/039.pdf. How to generate the public key? Should I compute it as indicated in section 2 : $h(i) = 2g(i)*... 0answers 35 views ### ECSchnorr Still getting wrong (hash?) results [closed] I'm writing Schnorr signature algorithm on elliptic curves. I get instructions from here (page 128) Here's my code ... 0answers 127 views ### MD5 hash different between sources - different hash for the same string [closed] I've implemented the md5 source from a crypt lib from http://sourceforge.net/projects/libcrypt/ The string I'm passing to md5 is ... 0answers 30 views ### JS libraries or tutorials that utilize deep learning like Netflix [closed] I am looking for JS libraries or tutorials that have implemented a deep learning approach, to make predictions. The best example is Netflix who predicts what you like based on your past seen movies. ... 0answers 113 views ### Simplest way for strong cryptography in chat I am a beginner in cryptography and I am interested for several weeks on this for my chat application. Basically, it is a centralized model. All messages are stored and potentially visible by ... 2answers 81 views ### Initializing PGP keys by one side I am using a PGP method to encrypt and decrypt messages shared between users A and B. Upon the start of a message exchange is the initialization of the public and secret keys by both Users. Lets say ... 0answers 56 views ### equation of mixcolumn in the aes field$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 ... 0answers 55 views ### Is it possible to combine cryptography with steganography [closed] Definitions: M - original message, Me - encrypted message M, S - watermark message, Ms - message M with steganography watermark S, e - encryption private key, d - decryption key (it is private too), s ... 0answers 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 ... 0answers 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 ... 0answers 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 ... 0answers 83 views ### Carrying out a known-plaintext attack on a cipher [closed] Previously posted here. Someone suggested I could post it here to get some answers. I am trying to solve a CTF challenge, here. Basically we're given message and key inputs to a cipher and its ... 0answers 560 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-... 0answers 13 views ### Transforming EC public key X and Y-sign into X and Y [duplicate] I'm using bouncycastle which uses X and Y coordinates for public keys. An EC public key is more compactly represented by the X coordinate and the sign of the Y coordinate. How do I use bouncycastle ... 0answers 117 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 ... 0answers 114 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 [... 1answer 55 views ### For hardware encryptions, is it possible to know the key by analysing the hardware? For example, Square reader uses hardware encryptions when swiping credit cards. Is it possible to know the key that is used by the hardware encryption cipher by analysing the hardware circuitries? ... 1answer 40 views ### For the scrypt HMAC storage format, why run the input of the hash and the hash itself into the HMAC Generally if the body is hashed, why provide the body and the hash as input into the HMAC. Instead wouldn't the same security be achieved by hashing the body and providing only the hash as input into ... 0answers 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 ... 0answers 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 ... 0answers 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? 0answers 160 views ### Weird base64-like (?) encoding [closed] I have some encoded strings which are probably encoded in a base64-variant - except that there aren't only 64 chars, but all the (printable) ASCII chars between 33 and 126 (0x21 to 0x7E). I've ... 0answers 22 views ### Understanding CPA and CCA Secure [duplicate] CPA attack means the attacker can send in his own plaintext to the oracle and receives some sort of ciphertext back. CCA attack means the attacker can send in his own ciphertext to the oracle and ... 0answers 31 views ### Data in frequency modulated audio [closed] I'd like to have a peek at the firmware of a piece of Hardware. Its firmware is available as a .wav file to be uploaded via audio jack. https://drive.google.com/open?id=0B6S_PcWWM1YlQnNwT2FSMnFzVE0 ... 0answers 27 views ### ephemeral-ephemeral ECDH and MITM attack [duplicate] ephemeral-ephemeral ECDH is it susceptible to MITM attack ? if yes, can you please give me a detailed answer ( Workflow that can be followed by the attacker) and how we can prevent this attack (static-... 0answers 32 views ### Why the group order has to be prime for pairing-based cryptography [duplicate] I'm trying to get into pairing-based cryptography and I don't see why the group order of the group G in the pairing function e:G*G-> G_t has to be a prime number. I don't find an argument why ... 0answers 92 views ### Encrypting a 160-bit plaintext into a 160 bit ciphertext with a 128-bit Block Cipher [closed] So I have a kind of interesting issue. I have a field in my data store which must take exactly 160 bits of information. Some users will choose to make this data encrypted, some won't, so some of those ... 0answers 46 views ### 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 ... 0answers 70 views ### Powerline password conversion [closed] I read this post from Ben Tasker describing how to take control of a powerline network. Since I am interested in security, I tried to do the same thing, to see if it was possible. I used Devolo ... 0answers 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 ... 0answers 212 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 ... 0answers 44 views ### research on Encryption for master [closed] I'm tring to choose an way for an Encryption mothod for my research? So,I want to choose one-layer encryption or multilayer encryption,and I want it to be easy to applicable. when I search about it, ... 0answers 43 views ### 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 ... 0answers 36 views ### If I know the hash function that produced a hash key, how easily can I generate an input to hash to the same key? [duplicate] The title is pretty descriptive of my question. As an example, say I use the MD5 hash function to create a hash key of the word "hello": 5d41402abc4b2a76b9719d911017c592. There are two questions I ... 0answers 25 views ### 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$... 0answers 29 views ### If you were to design a PKI from scratch, what would you do? [closed] In what ways would you simplify? What would be changed to be more modern or extensible? Suppose you have no requirement to adapt to previous protocols. Links to proposed designs, existing protocols,... 0answers 41 views ### Symmetric stream cipher, is it known? I am thinking on a simple symmetric stream cipher. My first idea is the following: The key is a set of array of random bytes ($\underline{k}_1$...$\underline{k}_n$), whose length is$l_1$,$l_2$, .... 0answers 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 ... 0answers 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, ... 0answers 57 views ### 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 ... 0answers 808 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 ... 0answers 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 ... 0answers 288 views ### How do I create a PKCS#7 or CMS SignedData in python? [closed] There doesn't appear to be PKCS#7 or CMS support in pyCrypto. I'd appreciate a recommendation on a Python library wth CMS / PKCS#7 support. Ideally, there will be a call that will create return ... 0answers 34 views ### Open source code about the basic Quisquater-Piret DFA of AES-128 [closed] Where can i find open source code about the basic Quisquater-Piret DFA of AES-128? Are there any websites sharing the code about such physical attacks? 0answers 71 views ### Can a block cipher encrypt the message to itself (plaintext equal to ciphertext) [duplicate] The result of the cipher should be indistinguishable from random, but can it happen that cipher produces the ciphertext that is equal to the plaintext as it also lies in the corresponding space? I ... 0answers 51 views ### Concepts for realization in applied cryptography [closed] I'm a computer science student (not a mathematican) and I'm gonna to write a master degree diploma on applied cryptography. Specifically, I'd like to create a realization of some cryptographic stuff ... 0answers 16 views ### Is there any equivalent to the apache xml security library for JSON? [closed] I'm talking about org.apache.xml.security(santurio) Is there any equivalent library that works with JSON and provides the same set of features? (mostly AES-128 with KEK support) 0answers 71 views ### In DGHV FHE, why noise$r$can be in$(-2^{\rho'}, 0)$? "Fully Homomorphic Encryption over the Integer" described a simple FHE scheme based on the GACD assumption. Its encryption function (on page 6) has the form$c \leftarrow (m + 2r + 2*\sum_{i \in S} ...
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 ...