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1500 questions
31
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2 answers
What is a white-box implementation of a cryptographic algorithm?
What is a white-box implementation?
Does a white-box implementation have specific properties?
ir01
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31
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5 answers
Why are primes important for encryption
Why are primes so important? Why can't we just use a random number?
My guess is that it's because finding a random prime require more computing power, than finding a random number. Can anybody confirm this?
KaareZ
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31
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3 answers
Why we can't implement AES 512 key size?
Out of curiosity why we can't implement AES 512 key size?
Please explain somehow i can understand! I'm not an expert.
hamedb71
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31
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Is HMAC-DRBG or Hash-DRBG stronger?
Out of the two deterministic random bit generators defined in section 10.1 of NIST SP 800-90A (i.e. based on hash functions), which one is cryptographically stronger?
Hash-DRBG (Section 10.1.1)
HMAC-DRBG (Section 10.1.2)
Is there any other…
Lunar Mushrooms
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31
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3 answers
Is it possible to derive the encryption method from encrypted text?
Is it possible to identify the encryption method, or at least rule out some of them, by looking at the encrypted text?
For example, if you have 3 encrypted strings where the first 10 characters are the same on each of the strings.
Shiraz Bhaiji
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31
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2 answers
When using Curve25519, why does the private key always have a fixed bit at 2^254?
When using Curve25519, the private key always seems to have a fixed bit set at position $2^{254}$.
Why is that? Is there any good reason to use a fixed positioned most-significant-bit in the private key?
Trina
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31
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9 answers
RSA with small exponents?
Just to establish notation with respect to the RSA protocol, let $n = pq$ be the product of two large primes and let $e$ and $d$ be the public and private exponents, respectively ($e$ is the inverse of $d \bmod \varphi(n)$). Given a plaintext…
Elliott
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30
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4 answers
Why is FIPS 140-2 compliance controversial?
I was reading the comments of an article about a proposed new implementation of /dev/random in Linux today, and someone remarked that it must be bothersome to go through 43 revisions and still not have your patch landed. A few comments down the line…
Newbyte
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30
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4 answers
Assuming a 1024qb quantum computer, how long to brute force 1024bit RSA, 256bit AES and 512bit SHA512
Assuming in the future there was a functioning 1024 qubit quantum supercomputer and it could run Shor's algorithm or Grover's algorithm to crack encryption very quickly. I'm interested in how the number of qubits translates to performance…
user7827
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1 answer
How was this 2048 bit number factored so fast?
I'm working on a CTF. The challenge is to get the contents of an encrypted message given the ciphertext and the 2048-bit RSA public key. I did finally get the flag after a few hours, but I'm still not sure why the first step worked.
The first step…
rainbowkitty227
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5 answers
Other than password hashes, are there other uses for non-reversible crypto
Hashing is useful for checking that an input matches expectations without giving away the stored expected version - so confirming passwords etc.
But are there other use cases? In general, cryptographic storage so data is retrievable seems to be the…
Rory Alsop
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30
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8 answers
Can you use memory errors as a source of randomness for cryptography?
Obviously, if you need a random number for cryptography, your code should use an api that gets it from hardware. However, not all hardware has a SRNG available. If you are working on a security critical application, and hardware RNG is not available…
TheCatWhisperer
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30
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2 answers
Rubik's Cube as Encryption
Consider this scenario:
Alice gets a Rubik's Cube and peels off the colors from each piece. She then writes a small message on one of the faces of the cube and fills the remaining pieces with random letters. Then, she scrambles the pieces in a way…
yasar
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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
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30
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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
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