All Questions

542 views

Why are elliptic curves better than cyclic groups?

The set of points of an elliptic curve over a finite field is isomorphic to the direct product of two cyclic groups (i.e. $E(F_{p^n}) \cong Z_{s} \times Z_{t})$. What is the advantage of representing ...
492 views

Map Bytes to Number

Using node.js crypto library I can generate cryptographically strong bytes. How can I use this to generate a random number between 0 and 9999 (both inclusive)?
239 views

Digital Signature Scheme Count

My question is How I will be able to count digital signature Scheme that can sign many documents with one private key. There are signature scheme as long as exists private keys in the keys spaces? or ...
4k views

What are some disadvantages of homomorphic encryption schemes?

I'm doing some self-teaching / research for my own benefit in homomorphic cryptography. I've studied both additive and multiplicative schemes (Pallier and RSA respectively), but all I can seem to ...
334 views

Signature with appendix

I see sometimes signatures schemes with appendix. This is about signatures schemes in which the message is needed in the verification algorithm, that is, the ouput of the signature algorithm is of the ...
266 views

How did they factor RSA-704?

I don't understand the 'Wiedemann algorithm' works. Can someone explain the factoring of RSA-704 in an easy way?
845 views

Is a PBKDF2-derived master key easier cracked if very many Data Protection Keys are derived from it?

I'm referring the NIST document about PBKDF2, NIST Special Publication 800-132, Recommendation for Password-Based Key Derivation, Part 1: Storage Applications, Page 8 and 9, section 5.4 Using the ...
923 views

If we can find prime numbers larger than 17 milion digits, why can't we find all 1024bit primes? [duplicate]

"Largest Known Prime Number Discovered; Has 17,425,170 Digits" http://www.sciencedaily.com/releases/2013/02/130213225424.htm If we can find prime numbers larger than 17 milion digits, why can't we ...
143 views

How to build a secure AE scheme with generic composition?

I am actually looking for using a secure Encrypt-Then-MAC AE scheme , and consider using either an existing "ready-to-use" dedicated AEAD mode (GCM, OCB, CCM, EAX, etc ..) or an alternate composed ...
551 views

How practical is proxy re-encryption for AES?

In proxy re-encryption schemes, a proxy is given special information that allows it to translate a ciphertext under one key into a ciphertext of the same message under a different key. How ...
277 views

Using AES-CBC and providing the IV in file header -> security hole? [duplicate]

currently I audit some code I've written in the past to use KeePass 1.x databases. I stumbled over the following question: The database itself is decrypted with AES-CBC and inside the file header the ...
263 views

How is key rotation defined?

I'm aware that it's advisable to rotate cryptographic keys periodically. HKDF accepts high-entropy input (IKM - Input Key Material), and expands it to an arbitrary length. It also accepts a salt, ...
82 views

How does the possible attack on passwords and salts mentioned in PKCS#5 v2.1 work?

From PKCS#5 v2.1, 4.1 Salt (page 6, emphasis by me), also in v2.0, RFC 2898: In password-based encryption, the party encrypting a message can gain assurance that these benefits are realized ...
280 views

How to pad messages with large amount of padding

I'm playing around with an application for secure email-like communication and I want to perform length hiding padding on the plaintext messages so they always have a consistent size before encrypting ...
1k views

Help with example RSA problem

While learning about RSA, I found this example problem. The answer is supposed to be "a 4-digit number that is a pattern of digits." I have computed it to be 16657 twice. OK, now to see if you ...