Most Popular
1500 questions
30
votes
3 answers
Dropbox Password security
Dropbox have recently published How Dropbox securely stores your passwords
Is this really more secure than using bcrypt with a complexity of 11 or 12 ?
The password "chain" is secure as its weakest part, so is there any point adding the extra 2…
exussum
- 403
- 4
- 7
30
votes
2 answers
In which cases should the IV be kept secret?
When must an IV be kept secret?
There is an ambiguity in the way that the lack of need for secrecy of the IV is described in multiple places. Does this ambiguity suggest that there are, in fact, situations in which the IV must be kept secret? Or…
gowenfawr
- 640
- 7
- 12
30
votes
4 answers
Why are zk-SNARKs possible, in layman's terms
zk-SNARK: Zero-Knowledge Succinct Non-interactive Argument of Knowledge
From the Ethereum blog:
One natural use case for the technology is in identity systems. For example, suppose that you want to prove to a system that you are (i) a citizen of a…
bkoodaa
- 639
- 7
- 12
30
votes
1 answer
How was the special DES key 0E329232EA6D0D73 found?
The DES key 0E329232EA6D0D73 has the unusual property that decrypting a ciphertext block consisting entirely of zeros gives a plaintext block consisting of eight repetitions of the same byte (0x87).
How was this key originally found?
prim
- 303
- 3
- 6
30
votes
3 answers
What is the recommended number of iterations for Argon2?
I've recompiled my operating system ("LionBSD" based on FreeBSD) to use Argon2i as the default password hashing algorithm in crypt/libcrypt.
I'm wondering what the recommended number of iterations would be?
As an example, OpenBSD uses 8 iterations…
fizk
- 435
- 1
- 5
- 6
30
votes
4 answers
What is the effect of the different AES key lengths?
How does a changing key length affects the ciphertext, not only in case of AES, but in general? I know that the key spaces become much larger and the number of rounds in case of AES changes, but is security really that much enhanced that if I choose…
tom
- 397
- 1
- 3
- 3
30
votes
1 answer
what is the difference between proofs and arguments of knowledge?
What is the difference between proofs and arguments of knowledge in the context of zero-knowledge?
I have read this sentence in this ePrint:
It is useful to distinguish between zero-knowledge proofs, with
statistical soundness, and zero-knowledge…
MH Samadani
- 591
- 4
- 12
30
votes
11 answers
Why can't I reverse a hash to a possible input?
I'm going to provide “proof” why a hash function can be reversed, and I hope you can tell my why I'm wrong
So, a hash function can be implemented as a series of logic gates. All logic gates can be implemented using only NOT and OR gates. (I'm fairly…
Shelvacu
- 574
- 1
- 5
- 10
30
votes
3 answers
Is this password migration strategy secure?
I want to upgrade the security of some existing databases of users' authentication tokens strictly for the purpose of making sure that if the database is stolen, attackers will not be able to guess any but the weakest passwords in a reasonable…
Major Major
- 435
- 4
- 7
30
votes
2 answers
How to determine the order of an elliptic curve group from its parameters?
Let $\quad E:\; y^2 = x^3 + ax + b \quad$ be an elliptic curve defined over a finite field $\mathbb F_q$ where $q = p^n$, $a,b \in \mathbb F_q$ and $p \neq 2, 3$. By Hasse's theorem we know that the order of $E(\mathbb F_q)$ is in the range…
user110219
- 665
- 1
- 6
- 12
30
votes
1 answer
SHA-256 hash of null input?
What is the SHA-256 hash if the input is null, i.e. an empty bitstring? (Not the hash of 0 or "0".)
Geremia
- 625
- 1
- 5
- 12
30
votes
1 answer
How strong is the ECDSA algorithm?
Some cryptographic algorithms are as strong as the size of their key is, while other have some weaknesses that limit their strength (such as SHA-1). How strong is the ECDSA algorithm, and does that strength depend on anything (for example, the curve…
ThePiachu
- 1,689
- 2
- 18
- 26
30
votes
2 answers
Which attacks are possible against raw/textbook RSA?
The PKCS#1 standard defines multiple padding schemes for signature generation/verification (EMSA-PSS and EMSA-PKCS1-v1_5), and encryption/decryption (EME-OAEP and the less safe EME-PKCS1-v1_5).
Which attacks are possible on signature…
Maarten Bodewes
- 96,351
- 14
- 169
- 323
30
votes
2 answers
How does the MOV attack work?
What exactly is the MOV attack, how does it actually work, and what is it used for?
It's explained briefly here and I'd like to know what it is more / what is it fully used for.
Ben
- 749
- 1
- 7
- 13
30
votes
1 answer
How secure would HMAC-SHA3 be?
It would be possible to implement the HMAC construction with (draft) SHA-3, leading to HMAC-SHA3-224, HMAC-SHA3-256, HMAC-SHA3-384, HMAC-SHA3-512 (the last 3 digits are the output size $\ell$, where $\ell/8$ is the $L$ parameter in HMAC). All that's…
fgrieu
- 149,326
- 13
- 324
- 622