CodesInChaos

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bio website github.com/CodesInChaos
location Munich, Germany
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visits member for 1 year, 10 months
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Nov
7
 comment 128 bit hash with least chance of collision
if you're worried about malicious collisions, I'd consider using larger hashes. Even for perfect hash-functions, brute-force collisions on 128 bit hashes seem possible. Personally I'd go with 256 bit hashes if collision resistance is required.
Nov
5
 comment Why doesn't CTR mode require blocking?
"CTR requires that the key and the nonce be of identical size" No. The nonce size corresponds to the block-size, but the key-size is completely independent. For example AES-256 has 128 bit blocks (and thus nonces) but a 256 bit key.
Nov
5
 comment Finding partial pre-image of MD5 hash
With a GPU it's even faster, taking only a few seconds. See oclHashcat performance
Nov
4
 answered Crack cryptographic hash functions using Toffoli gates?
Nov
4
 comment finding collision for truncated SHA1 hash output
I don't think there is a faster way. But 2^20 SHA-1 invocations take less than a second.
Nov
4
 comment finding collision for truncated SHA1 hash output
Just hash about 2^20 times, then you'll get one 40 bit prefix collision.
Nov
4
 revised Finding partial pre-image of MD5 hash
edited tags
Nov
4
 comment Finding partial pre-image of MD5 hash
Short answer: No, there isn't. So use brute-force. But if you use a GPU it'll just take a few seconds to find such an $X$.
Nov
3
 answered Can there be two hash functions without common collisions?
Nov
3
 revised vigenere wiki excerpt
added 146 characters in body
Nov
3
 wiki created vigenere excerpt
Nov
3
 suggested suggested edit on vigenere tag wiki excerpt
Nov
2
 revised How can I break a Vigenère cipher with partial plain text?
deleted 7 characters in body; edited tags; edited title
Nov
2
 answered How can I break a Vigenère cipher with partial plain text?
Nov
1
 reviewed Approve suggested edit on Does gpg's symmetric encryption keep information about the filename?
Nov
1
 reviewed Edit suggested edit on Does gpg's symmetric encryption keep information about the filename?
Nov
1
 revised Does gpg's symmetric encryption keep information about the filename?
typo corrected
Nov
1
 comment Can you use the same key to provide a signature and a MAC?
What exactly do you mean by a signature? And you should specify the exact schemes you want to use. With common terminology a signature uses asymmetric crypto, a MAC symmetric. So you need different kinds of keys for that.
Oct
30
 reviewed Approve suggested edit on How can I prove in zero knowldege that an ElGamal shuffle is correct for a special setting?
Oct
29
 comment Can ElGamal encryption and ElGamal signatures be used together sharing the same key-pairs?
Can you store a single seed in the device from which you derive the two actual private keys with a KDF? That way you get a single small private key. But obviously it doubles the size of the public key.
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