Cryptography Weekly Newsletter
Cryptography Weekly Newsletter

Top new questions this week:

Examples of modern, widely used ciphers that suddenly fell?

RC4 and GOST are two major ciphers (defined as being widely used to encrypt large amounts of data) that fell to cryptanalysis (relatively) suddenly. The first becoming totally broken and the second ...

reference-request history  
asked by Demetri 23 votes
answered by Biv 29 votes

Algorithm for Boneh and Durfee attack on RSA

I am trying to understand various attacks on RSA and I believe that they only way to fully understand the algorithm is to implement it. I am trying to implement the code in this paper (pdf) (Private ...

rsa cryptanalysis attack  
asked by Node.JS 9 votes
answered by Reversal 1 vote

How to prove the security of block ciphers

I see very often proofs of security for asymmetric crypto algorithms, for instance, using reductions to known hard problems, or game based proofs... In the field of protocols (like authentication) it ...

block-cipher provable-security security-definition  
asked by Vitor 8 votes
answered by J.D. 4 votes

Is every point on an elliptic curve of a prime order group a generator?

If the order of elliptic group is prime then every point is a generator of that group. I tested the above statement on some elliptic curves and found it true. Does that really work on all curves? Is ...

elliptic-curves reference-request group-theory  
asked by Rashmi 6 votes
answered by diagprov 10 votes

How distinct are the meanings of the terms "CSPRNG," "DRBG" and "stream cipher"?

Are there universal, consensus definitions for the following terms? Cryptographically secure pseudo-random number generator ("CSPRNG") Deterministic random bit generator ("DRBG") Stream cipher ...

random-number-generator stream-cipher pseudo-random-generator terminology csprng  
asked by Luis Casillas 6 votes
answered by otus 4 votes

Why do we use hex output for hash functions?

Why do we use hex representation as default for the output of a hash functions result? For example the sha256 hash function: the output of sha256 in hex representation uses 64 characters, while ...

hash password-hashing  
asked by Maarten Schermer 5 votes
answered by Thomas Pornin 7 votes

Strength of $H(k\|H(m))$ as a MAC algorithm

What is the strength of $H(k \| H(m))$ compared to HMAC? Compared to $H(m \| k)$? What is the strength in bits of a given key/output size?

hash hmac mac  
asked by Melab 4 votes
answered by CodesInChaos 4 votes

Greatest hits from previous weeks:

What is the difference between PKCS#5 padding and PKCS#7 padding

One runtime platform provides an API that supplies PKCS#5 padding for block cipher modes such as ECB and CBC. These modes have been defined for the triple DES, AES and Blowfish block ciphers. The ...

encryption aes block-cipher modes-of-operation padding  
asked by Maarten Bodewes 36 votes
answered by Maarten Bodewes 45 votes

Why does my SSH private key still work after changing some bytes in the file?

I (for a test) just randomly altered a private RSA key by opening it up in Vim and changing a few bytes. It is the private part of an SSH key pair used for logging in on a remote system. Puzzlingly, ...

rsa public-key authentication ssh  
asked by PhilPotter1987 45 votes
answered by yyyyyyy 67 votes

Can you answer these?

Yaos Millionaire Problem: Why distance >= 2?

I'm currently reading about Yao' Millionaire Problem: http://research.cs.wisc.edu/areas/sec/yao1982-ocr.pdf Alice and Bob want to know which of them is richer. Let $j \in \{1, \cdots 10\}$ be Bobs ...

protocol-design oblivious-transfer  
asked by Calculatrix 1 vote

Is 3 rounds more secure than 2 in this simplified DES?

Consider the following simplification of DES: a plaintext message block of $2n$ bits of length is divided into two blocks of length $n$ (left half $L_0$ and right half $L_1$). In other words, the ...

block-cipher des  
asked by lockerz 1 vote

Statistical tests for PRNG that generates a sequence which is not binary

Is there a pratical application to PRNG that generates a sequence which is not a binary one? A ternary, quaternary sequence, for instance. If so, how can we test this? Is there any alternative test ...

pseudo-random-function statistical-test  
asked by faith 3 votes
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