Linked Questions

7
votes
4answers
317 views

Can I replace SHA-1 with SHA-512/160 to address Shambles?

The destination is software (within a remote trust boundary) that expects SHA-1 results. Would it be safer for the source (that's within my own trust boundary) to replace my SHA-1 computation at my ...
37
votes
3answers
7k views

Does “Shattered” actually show SHA-1-signed certificates are “unsafe”?

Note: I am not advocating anyone continues using SHA1-signed certificates: they are dead as far as security is concerned and should no longer be used. I'm just trying to clarify my understanding of ...
17
votes
3answers
10k views

After Google's collision attack, is RSA-SHA1 signature still safe?

Google succeeded to get a collision in SHA-1 last year in an attack called shattered. Does this fact make certificates based RSA-SHA1 Signature risky for creating fraud certificates? If RSA-SHA1 ...
7
votes
3answers
6k views

Is it possible to find the key for AES ECB if I have a list of plaintext and corresponding ciphertext?

Assume I have a list of plaintext text and its corresponding ciphertext which was created using a specific key with AES in ECB mode. Can I recover that key? If, how big does the list of plaintext ...
5
votes
3answers
3k views

Has AES-128 been fully broken?

Has AES-128 been broken over the full 10 rounds? If so, by what means? By a commercial entity? By a supercomputer? If not, why is AES-256 used to replace AES-128 so frequently?
6
votes
2answers
2k views

Argon2 for both password storage and key derivation

Is using Argon2 for both password storage and key derivation secure? I'm planning on using different salt values, of course. The basic concept is something like this: Alice has some secret data ($...
4
votes
2answers
1k views

Is it hypocritical to use AES-256 and RSA 2048 in the same application?

I see a common claim that AES-256 is the gold standard and is good future proofing, often in the same wind as "just use 2048-bit keys for RSA". Security documents seem to recommend both AES-256 and ...
1
vote
2answers
105 views

AES-128 with doubled 8Byte key

Assuming I encrypt data with AES-128 and a random 8-byte key x in the following way: ...
1
vote
2answers
261 views

Hash collisions in sha512 hash of secp256k1 public keys

For a sha512 hash of a secp256k1 public key, how many other public keys could generate that hash? I would assume zero since the key size is equal to the hash length (secp256k1 public keys are 64 bytes,...
1
vote
2answers
73 views

What is meant by encrypting/decrypting a known plaintext/ciphertext with every possible key in meet-in-the-middle?

I am working on the Meet-in-the-middle attack on 2DES and I have got some questions I am not sure about. I read several websites/articles about it so I have got an idea of what it is and how it works. ...
1
vote
2answers
272 views

DES - encrypt 3 times - DES(DES(DES, k), k'), k) - stronger than 2DES with 2 different keys?

What if were to use DES in the following way: For a given plaintext x and key k we will perform: ...
16
votes
1answer
8k views

In 2020, SHA-1 practically broken in chosen-prefix collision (CP-collision). Can double SHA-1 hashing prevent CP-collision?

In a recent study SHA-1 is a Shambles - First Chosen-Prefix Collision on SHA-1 and Application to the PGP Web of Trust by Gaƫtan Leurent and Thomas Peyrin. 2020, they showed the first practical chosen-...
4
votes
1answer
349 views

Worth taking performance hit of HMAC to gain additional security?

It seems like SHA-512 truncated to 256 bits is usable as a MAC [1]. The advantage is that it's ~50% faster than HMAC-SHA-256 on 64-bit CPUs and ~50% faster than HMAC-SHA-512 on short inputs. (My use ...
3
votes
1answer
118 views

Do ciphers with a key size of 64 bits still have use under very limited attack models?

If we have a very performance critical interactive session, like a video game, running on a trusted platform (video game console). If our goal is to prevent exfiltration of up to date information (...
2
votes
1answer
99 views

SHA-256 security for initial 32 bits

I have concerns regarding truncated SHA-256 hashes in an application I am building at the moment: Nomenclature secret - the full 256-bit SHA-256 result of hashing ...
2
votes
1answer
274 views

Partial Known Message Pre-Image Attack on SHA-1

If the last 448 bits of a sha1 block input are known (only the first 64 bits are unknown). Is it possible to do a preimage attack using SAT solvers or something else? Or do I have to brute force all $...
1
vote
1answer
127 views

80-bit security and attack time

Many designer claimed that their cryptography scheme has 80-bit security. So how to calculate the time of attcking this 80-bit security cryptography scheme, such as 80-bit security RSA using a kind of ...
1
vote
1answer
57 views

MD5 hash: retrieve an element of a source string

Suppose you have a string, precisely an MD5 hash string, which basically it is computed in the following way: "element1:element2:element3" So, in order to get ...
1
vote
1answer
77 views

Good pre-image resistance value for hash visualization

I want to do "hash visualization", i.e. derive a human-meaningful information from a hash, like a phrase or an avatar. But the current techniques usually don't use many bits, for example tripphrases ...
1
vote
1answer
124 views

Supercomputer to crash hash

For NVIDIA TESLA V100 I know a hashcat performance for SHA1: it is about 17000 MH/s. Performance index for V100 is FP32 5120, FP64 2560. But what about supercomputers? For example Summit ...
1
vote
1answer
56 views

Algorithm/encryption technique which outputs a set number of numerical digits e.g. 20 digits from a given input

What the name of the algorithm/encryption technique which outputs a set number of numerical digits e.g. 20 digits based on some input. You can input some data e.g. text or numbers but the output is ...
1
vote
1answer
189 views

How to make my hash more robust to the brute force?

I'm using PBKDF2 SHA 256 with 100 000 iterations to generate a secret. I want to increase the cost of brute forcing the passphrase I use to generate the secret. I'm thinking of using scrypt after ...
1
vote
1answer
279 views

Given partial key exposure and encryption oracle, can we recover full AES key?

Suppose I have an encryption oracle for AES with some key $k$ (16 bytes) and that I know $n$ bytes of it. Is it possible to recover the rest ($16 - n$) in complexity less than $256^{16-n}$?
0
votes
1answer
68 views

Calculating DES key knowing message before and after encryption [duplicate]

I've 8 bytes before encryption (for example: 01 02 03 04 05 06 07 08) and 8 bytes after DES encryption: ...
0
votes
1answer
97 views

Finding and matching SHA512 Unsalted Hash

We are given a list of possible strings, there are $32^{16}$ ($=2^{80}$) to be exact. We also have the unsalted SHA512 of the original target string. How long would it take to go through those ...
0
votes
1answer
316 views

Show that if a fixed key MAC is not collision resistant then the MAC function is not computation resistant for every key K

I'm really having some trouble with this one. Let $H$ be a MAC function. For every key $K$ we can create an unkeyed hash function (i.e.an MDC) by using $H$ to hash messages with the fixed key $K$. ...
1
vote
0answers
39 views

Can Trivium ciphertext be decrypted by an adversary if the key is known, but the IV is not?

Suppose that the adversary is able to recover the key of Trivium cipher. But the associated IV is unknown to him. Will he be able to decrypt the ciphertexts without any complexity?
0
votes
0answers
97 views

How reassuring is 64-qubit security?

After we've concluded that 64-bit is an insecurity for classical computers, I think many would like to know, how secure in a perspective view, is 64 quantum bits security. As we know, the Grover's ...