Linked Questions

6
votes
1answer
1k views

Choice between AES-128 and AES-256 for password protection in MS Office

Why are we still using the default of AES-128 when password protecting a Microsoft Word document. My answer is and always has been - because its good enough and MS don't recommend changing to AES-256. ...
4
votes
3answers
1k views

How confident can we be that nobody will crack a 128-bit key?

In a context involving a block cipher like AES-128, excluding quantum computers, cryptanalytic breakthrough on AES and implementation attacks (poor TRNG, DPA..), and wrench, how confident can we be ...
11
votes
5answers
3k views

Suppose I capture encrypted data that I want to decrypt. Could I use a server farm to decrypt?

For argument's sake, let's say that I'm a bad actor who produces malware. I've infected around 10,000 computers and smartphones with my malware, which runs in the background and can be used to make ...
0
votes
1answer
31 views

Vulnerability of low value generated key

I have read here that Elgamal is resistant to brute-force attack, because the group to where the key is selected is very large. But since the key generation is random, (i assume)there is a chance that ...
3
votes
1answer
3k views

ECC keys vulnerable to brute force attack?

I have started learning about Elliptic Curve Cryptography (ECC). Since the key size required in ECC is relatively smaller than the key size in RSA (to provide the same encryption strength), I wonder ...
2
votes
1answer
84 views

Maximum security strength in bits of ISAAC cipher?

Wikipedia claims key length can be very big in this cipher, so I assume it can offer a million bits of security provided entropy of key is the same? Of course I can SHA-256 hash the key to allow any ...
8
votes
4answers
32k views

How long would it take to brute force an AES-128 key?

How long would it take to crack a AES-128 key using the most advanced technology currently available? The hardware can be anything, be it a high-performance CPU, GPU or even FPGA?
40
votes
10answers
11k views

Differences between industrial and military cryptography

Industrial and military cryptography should follow the same basic rules, but what does make them different is: Higher key length, protocols unknown to the civilian world, and perhaps unique methods ...
0
votes
2answers
1k views

How to calculate a private key from public key on elliptic curve? [duplicate]

Provided, that you have to multiply a well known G by the private key to obtain the public key, why not keep adding G to itself until you reach the public key. The private key should be the number of ...
2
votes
4answers
770 views

Why can't we give block ciphers larger keys?

I have limited math's knowledge so sorry if this question sounds stupid. I saw many people complaining about AES, Twofish and Serpent that these ciphers all could be crackable in the near future and ...
12
votes
2answers
19k views

Does SHA-1024 hash exist?

Does SHA-1024 cryptographic hash function exist similarly to SHA-512? If not, what's the reason for that? Links: SHA-2 at Wikipedia SHA-3 at Wikipedia
1
vote
1answer
194 views

Encryption using matrix transformations

I have been thinking lately about a block cipher which takes a block of bits and arranges them in a square matrix. Then defining transforms on submatrices of the square matrix to scramble the bits. ...
46
votes
6answers
34k views

Why is AES resistant to known-plaintext attacks?

At least it's my understanding that AES isn't affected by known-plaintext. Is it immune to such an attack, or just resistant? Does this vary for chosen-plaintext?
4
votes
2answers
71 views

Does a thermodynamic limit on key search apply to quantum computers?

There is (or at least was) a thermodynamic reasoning that any form of brute force key search would require an energy at least $k\,T$ per key tested, where $k$ is Boltzman's constant and $T$ the device'...
2
votes
2answers
1k views

Is this test result sufficient to steer clear from this RNG for cryptographic applications?

I'm not really interested in this PRNG. I'm more interested in understanding what it takes to fail the security threshold for cryptographic applications. I'm taking the C PRNG as an example. ...

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