Cryptography Weekly Newsletter

Cryptography newsletter

Top new questions this week:

Diffie-Hellman and man-in-the-middle attacks

See here for the man-in-the-middle attack on Diffie-Hellman that I'm concerned about: What is Diffie-Hellman? How do we combat this? I have two questions: Is one solution for both Alice and Bob …

signature diffie-hellman authentication certificates man-in-the-middle  
asked by Luke 4 votes
answered by Guut Boy 2 votes

The difference between being not strongly collision resistant, and not weakly collision resistant?

So I understand the two concepts: (Strong) collision resistance: it is infeasible to find a pair $x \neq x'$ such that $h(x) = h(x')$ Weak collision resistance / 2nd-preimage resistance: for all $x …

hash collision-resistance 2nd-preimage-resistance  
asked by 8128 4 votes
answered by David Cary 3 votes

Authenticating Very Short (Sub-Block) Data

If I'm encrypting very short/small data - like an int or a long (32 or 64 bits), does it make any sense to authenticate the ciphertext, when using an "online" mode of operation (like EAX)? …

aes authentication modes-of-operation authenticated-encryption eax  
asked by Dexter 3 votes
answered by Seth 5 votes

Finding algorithm: desire RSA's uniqueness and ECDSA's space efficiency

I am asking for help in finding a signature algorithm with the following property: Given a message m and a private key prikey, the result of signing m with prikey is unique (which is stricter than …

rsa signature ecdsa dsa  
asked by updogliu 3 votes

What is the technical name for a public key container in DER format?

I have a public key in the following (format-neutral; the type is specified by the DER bytes) format: $ cat pubkey.der | openssl asn1parse -inform der -i 0:d=0 hl=4 l= 290 cons: SEQUENCE …

reference-request terminology pkcs8  
asked by Mike 3 votes
answered by Mike 2 votes

Efficient AES - Use of T-tables

I'm really in trouble! I'm trying to understand how the T-tables in AES encryption work. But I don't know if I get the point. What I understood is that they are used to reduce the whole computation of …

encryption aes  
asked by gabribass89 3 votes
answered by user13741 1 vote

Ways to make a "doomsday" cryptocurrency which becomes untradable

As a social experiment (not a money-making scheme), I'm interested in developing a crazy cryptocurrency which, by its very design, will become worthless and untradable after a certain point. Ideally, …

protocol-design timed-release  
asked by Chris Conlon 3 votes
answered by otus 4 votes

Greatest hits from previous weeks:

Difference between stream cipher and block cipher

A typical stream cipher encrypts plaintext one byte at a time, although a stream cipher may be designed to operate on one bit at a time or on units larger than a byte at a time. A block cipher …

encryption block-cipher stream-cipher  
asked by Ravindra Bagale 7 votes
answered by PaĆ­lo Ebermann 8 votes

What are the practical differences between 256-bit, 192-bit, and 128-bit AES encryption?

AES has several different variants: AES-128 AES-192 AES-256 But why would someone prefer use one over another?

encryption aes block-cipher key-size  
asked by samoz 32 votes
answered by Thomas Pornin 34 votes

Can you answer these?

Understanding Pseudo Random Generators

I've been taking a crypto course online. I have a good idea how PRG's and Stream Ciphers work, but I'd love to get some input to help visualize what is actually happening. I understand a seed is used, …

stream-cipher pseudo-random-generator  
asked by Aaron Tracy 2 votes

Encryption with data loss protection

Is there an existing format out there that not only encrypts data but also protects against loss of data much like the QR codes can lose up to 33% of it's bits and the message is still recoverable. I …

asked by Alan Asher 1 vote

Is it feasible to use combination of ABE schemes for encrypting the data?

I have a peculiar requirement for preserving the shared log files. For example I have 1000 records which belong to different organizations as listed below and all the logs are present in a single CSV …

public-key identity-based-encryption attribute-based-encry  
asked by bhanu gopularam 1 vote
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