Cryptography Weekly Newsletter

Cryptography newsletter

Top new questions this week:

Dan Boneh's Cryptography lecture - problem with 802.11b

I am going through Dan Boneh's Cyprography lectures on Coursera. In Lecture 6 At 7:30 minutes, he discusses the problems with 802.11b design. I ...

keys stream-cipher prg  
asked by user93353 5 votes
answered by hakoja 8 votes

Why does an algorithm need a keyspace?

Why does an algorithm need a keyspace? I thought the person encrypting would define his/her own key.

asked by user1688175 4 votes
answered by Ilmari Karonen 11 votes

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 ...

provable-security random-oracle-model  
asked by cygnusv 3 votes
answered by Yehuda Lindell 0 votes

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 ...

standards pkcs11  
asked by user25339 3 votes
answered by Mr. Stone 0 votes

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 ...

asked by geoff_h 3 votes
answered by CodesInChaos 2 votes

El-Gamal and Lines on Planes

I've been thinking about a geometric picture for El-Gamal. The idea is to understand the set $\{(my^{x},g^x) \mid x \in Z_p\}$ (the set of encryption of $m$ for fixed $g$ and $y$) by taking the ...

reference-request discrete-logarithm elgamal-encryption universal-re-encryption  
asked by NaN 3 votes

AES and Homomorphic Encryption

Is it possible to do the following? Input would be to generate a new AES key, encrypt the private data with that key, encrypt the AES key with the FHE key, and send the FHE-encrypted AES key along ...

asked by Rima Shah 3 votes
answered by cygnusv 2 votes

Greatest hits from previous weeks:

Why is AES resistant to known-plaintext attacks?

At least it's my understanding that AES isn't affected by known-plaintext. Is it immune to such an attack, or just resistant? Does this vary for chosen-plaintext?

aes block-cipher known-plaintext-attack  
asked by Jeff Ferland 19 votes
answered by PaĆ­lo Ebermann 23 votes

Why shouldn't I use ECB encryption?

I'm using Java to generate encrypted strings, and I get this warning at build time: ECB encryption mode should not be used So I'm wondering why I shouldn't use ECB and what I can use instead?

encryption block-cipher ecb  
asked by Rogue 8 votes
answered by Guut Boy 14 votes

Can you answer these?

What is SRP-Z form?

The stanford license for SRP says: Broader use of the SRP authentication technology, such as variants incorporating the use of an explicit server secret (SRP-Z), may require a license; yet I ...

authentication srp  
asked by simbo1905 1 vote

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 ...

elliptic-curves modular-arithmetic montgomery-multiplication  
asked by NumberFour 2 votes

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 ...

rsa public-key signature  
asked by kub0x 1 vote
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