0
votes
0answers
8 views

Inner product with homomorphic encryption

I want to do a very simple thing: Given two vectors, I want to encrypt them and do some calculation, then decrypt the result and get the inner product between both vectors. Can you recommend me ...
2
votes
0answers
15 views

Is standardizing a modified AES a good idea?

"Recently" the Ukraine standardized a new block cipher Kalyna, which according to the abstract of this paper (warning: the paper contains a lot of test-vectors) is basically a modified version of AES. ...
0
votes
1answer
7 views

What is a man-in-the-middle attack (for instance in Diffie-Hellman)?

I'm new to cryptography and I just started learning about the Diffie-Hellman key agreement. I read that this system is vulnerable to a man-in-the-middle attack when used alone. What kind of attack is ...
2
votes
2answers
642 views

I hashed my bag and in it I put… “Is there a hash for unordered items?”

(By items I mean hashable objects.) As an example (with obviously way too short hashes for readability), say I packed my bag and in it I put a shovel (hashed to ...
1
vote
1answer
22 views

Pseudo Random Function

The definition of pseudo randomness that leads to pseudo random function talks about indistingishability of a key-ed function and a random function. i.e. The key-ed function family $\{F_k\}$ is PRF ...
1
vote
1answer
181 views

Suggestion : CRC vs SHA1

I need some suggestions about the use of the CRC in my application. I need to be sure about the BIOS run by the CPU. I have a FPGA between the BIOS flash and the CPU that sniff every read performed by ...
2
votes
1answer
23 views

Why should the input value on a DPA attack be non-constant?

I actually was wondering if anyone could help me out with the following problem: Let's assume we are attacking the first SubBytes() operation on AES with the help ...
0
votes
0answers
23 views

what do you mean by cost in encryption? [on hold]

What do you generally mean by cost of an encryption algorithm? how are they computed and how to compare the cost of two encryption algorithms?
3
votes
1answer
56 views

How often does RSA-OAEP have a leading zero?

We are working with a third party vendor who is very tight lipped about their security protocols, and one of our customers who used this vendor's products is claiming that approximately one in every ...
-1
votes
1answer
42 views

Theoretical Mathematics & Cryptography [on hold]

I read in Bruce Schneier's book ,"Applied Cryptography", that cryptographers need to study theoretical mathematics in order to be good at their job. Why is that?
1
vote
3answers
46 views

Is this client-side password hash scheme secure?

I want to build an app that uses client-side encryption for storing encrypted data on the server. A user-specific master key would be used, so to easily share it between devices a encrypted version of ...
0
votes
0answers
10 views

Creating disk image of encrypted disk [migrated]

I'm Fedora 21 user for some time and I'd like to create disk image to escape installing everything over again when something fails. I have encrypted storage and that fact makes me wonder. How do I do ...
3
votes
2answers
52 views

Does authenticated encryption add any protection to a signed digital envelope?

The general scenario of hybrid encryption is to use public key cryptography for the exchange of a one time session key that can be used for the encryption of the plaintext with a symmetric encryption ...
0
votes
0answers
25 views

Cryptographic Disk wiping with quantum random data?

I was thinking about using 4 Quantum Random Number Generators working at the same time to create a secure disk wiping system. Basically feed the random bits into to an approved DRBG then through an ...
2
votes
5answers
2k views

“123456” and “password” as crack standards

I know that when we encrypt, we use standard encryption technologies and to store data it's often stored as a hash. By encrypting a common password, for example "password" using ...
2
votes
0answers
25 views

What is SRP-Z form?

The stanford license for SRP says: ...
0
votes
0answers
3 views

Why do some programming language API's not support private key passwords? [migrated]

Two questions: I've recently started building a basic Go web-server, and noticed that the API for starting a TLS web-server does not support a symmetrically encrypted private RSA key. The API is ...
0
votes
0answers
41 views

Fast mental encryption algorithm? [duplicate]

Are there any algorithms that exist to encode messages written with pen and paper such that the messages can be encrypted/decrypted mentally? For example, Bob thinks of the text "This is my ...
0
votes
0answers
18 views

BKSQ Block Cipher implementation [on hold]

has anyone a working implementation of BKSQ block cipher? (preferably in c)
1
vote
1answer
59 views

Proving membership of a group without revealing identity

I have an interesting problem for which I've failed, so far, to find an elegant solution. Imagine that a user needs to repeatedly prove to public observers that they are a member of a trusted set ...
3
votes
1answer
79 views

Simulation aborted because the adversary doesn't use the random oracle

I'm trying to construct a proof for an encryption scheme in the Random Oracle model. This encryption scheme is like a PKE scheme but with an additional function that kind of "alters" ciphertexts ...
3
votes
1answer
89 views

EdDSA Signature Algorithm - hash of secret key

Why does EdDSA use the (SHA512) hash of the secret key as the exponent for the public key rather than using the secret key value directly? This seems inefficient and I can't see how it adds any extra ...
3
votes
1answer
38 views

Source for PKCS#11 Header Files

Is there a known authoritative source for the ANSI C header files for PKCS#11 Cryptoki? Specifically, I am having trouble locating pkcs11.h, pkcs11t.h, and pkcs11f.h for v2.30 and v2.40. Are there ...
2
votes
1answer
62 views

Ideas for non duplicate cryptographically secure numbers

My Boss asked me this today. I am not a math major. He needs to generate 50 billion non-sequential non-duplicate (no collisions) cryptographically secure random numbers. I work in GO. Any ideas?
1
vote
1answer
54 views

RSA function over $Z_t^{*}$ where $t$ is prime

RSA function is defined over $Z_N^{*}$ where $N=pq$ with $p,q$ primes. A public key is a pair $(N,e)$ and a private key is $(N,d)$ where $d=e^{-1} \mod \phi(N)$. Assume that RSA function is defined ...
0
votes
1answer
63 views

ElGamal scheme attack when one message is known and ciphertexts are intercepted

Let $G$ be a finite cyclic group of order $p$ and let $pk = (g, h=g^a)$ and $sk=(g,a)$ be Bob's ElGamal public/secret key pair in $G$. To encrypt a message $m$, a random number $r$ is selected and a ...
2
votes
0answers
70 views

What happens if no final subtraction is done in Montgomery multiplication?

I'm doing Montgomery arithmetic modulo $N = 2^{255}-19$ for the Curve25519, picking $R = 2^{256}$ for Montgomery. After multiplying two numbers $0 <= A,B < N$ in the Montgomery representation ...
-1
votes
0answers
44 views

“AND” concatenation of two secure PRGs

Let $G: \ K \rightarrow \{0,1\}^n$ be a secure PRG. Define $G'(k_1,k_2)=G(k_1)\wedge G(k_2)$ where $\wedge$ is the bit-wise AND function. Consider the following ...
0
votes
1answer
84 views

Double the key in block cipher - which approach is better?

Assume than you have a block cipher $E(k,m)$ for which the only attack exists has complexity of $2^{64}$. You consider to double the key size by either: $E'_1(k_1,k_2) := k_1 \oplus E(k_2,m)$ ...
0
votes
0answers
25 views

TLS encryption with a self-signed PKI and Python’s asyncio module

I want to enable TLS encryption with a custom / self-signed PKI for a self-contained distributed system built with Python 3’s asyncio. I’ve read Python’s ssl docs as well as several tutorials: ...
0
votes
0answers
21 views

How to multiply two field elements generated by bilinear paring map? [on hold]

I wish to clarify how to multiply two field elements generated by bilinear paring map. The following is an example where I need to multiply e1 and e2. is it possible? If yes, then how? FieldElement ...
1
vote
1answer
62 views

Extracting a WinRAR password

If I have an original file and a WinRAR password protected .rar file containing that file, than can I extract the password?
1
vote
1answer
28 views

Forgery attack on OCB

When using same nonce in OCB mode of authenticated encryption, how forgery attack can be done?
0
votes
0answers
32 views

Establish authentication

I have designed a basic authentication scheme where two nodes will mutually authenticate that other holds a shared secret. I have very limited RAM/ROM (its on uC) and bandwidth. Here it goes: ...
0
votes
2answers
43 views

HMAC-SHA1( secret key ) with header of a transmitted file

Given: an AES-128 secret key (ASecKey) encrypts a file (CBC mode). (Assume good random) Is is insecure to append (include) an HMAC-SHA1 of ASecKey to file? Purpose: The receiver can then quickly ...
1
vote
1answer
134 views

What is a “lattice” in cryptography?

There are some questions here concerning lattice-based cryptography and this kind of cryptography seems to be especially useful if quantum computers are assumed to exist. When reading such questions ...
1
vote
0answers
23 views

Machine readable, user non-readable - XML file [migrated]

I need some advice as I have been unable to find anything useful via the web - (Google search). I have used the application EventGhost so as to create a custom shell, that I run using the Windows 7 ...
2
votes
1answer
39 views

Security of MSS

I have started reading about the Merkle Signature Scheme. I am a little confused about why it is believed to be secure against quantum attacks, couldn't the hash function be attacked? What would make ...
2
votes
1answer
46 views

Block Ciphers - Standardize plain text

I need to use AES-128 to encrypt a plain text about 720 bits. Is it correct to say that – in this case – the plain text will be divided in 5 blocks of 128, the result will be equal 640 bits, and the ...
1
vote
1answer
27 views

Can I use HKDF to improve security of HMAC used with weak hash function?

I am writing a framework which encrypts/decrypts files (or streams, in general) with symmetric key using block cipher (for example, AES). To authenticate encrypted file, I use HMAC, which is ...
1
vote
0answers
21 views

RSA Signature Forgery

We all know that x509 certificates carry a signature that represents the certificate digest encrypted by the private key of the issuer. I believe that the digest is encrypted only providing one ...
1
vote
0answers
13 views

Logjam-style attack on Factoring?

We're all aware of the Logjam attack, which is known as "FREAK on discrete logarithms". Now the attack works by doing a large pre-computation step, which needs only to be done once per field and then ...
0
votes
2answers
32 views

Getting the encryption/has algorithm used for modem configuration file [closed]

Hello guys I have backed up my modem configuration file and found the username and password is in clear text; the files shows the username and the password is : ...
1
vote
1answer
58 views

Do all attacks against PKCS1 v1.5 encryption require an oracle

As far as I know, all attacks against RSA PKCS1 v1.5 require an oracle; is that true? Or are there any other attacks against it which are able to break it without an oracle? Background: I need to ...
1
vote
0answers
29 views

HMAC for encrypted authentication token: recommended iteration number [duplicate]

In the web application I use 10,000+ iterations for hashing passwords stored in database (random salt and all). Password-related operations are not frequent enough to create a noticeable performance ...
0
votes
0answers
28 views

How can a lattice attack be applied to ECDSA signatures?

The aim is to check if it is possible to break the ECDSA cryptosystem under the following criteria. Suppose that each ECDSA signature is generated by using the GLV method for point multiplication ...
0
votes
0answers
17 views

Transform RSA private key to ssh-rsa public key [closed]

I am generating a RSA key pair and write it to disk. I would like to transform the public key to look like this: ...
-1
votes
0answers
19 views

How to write automaticaly server generated keys into a file? [closed]

There have a server program, which generate keys for client. I want to store these keys into a file. I implemented the server and client program in python.. When server run each time for a user, the ...
1
vote
1answer
37 views

Derive cipher IV and cipher Key using PBKDF2 with random salt?

It is said that cipher IV does not have to be secret and the only secret component of the encryption scheme should be a cipher key. Question: is it safe to generate IV using PBKDF2 function, which ...
2
votes
3answers
69 views

Establishing encryption key using shared secret

I need to establish some security on a network of 8 bit microcontrollers. very limited RAM, CPU and packet sizes. I have zeroed in on a shared secret based scheme. Setting up shared secret is out of ...

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