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14

Definition In the Damgard-Merkle construction for hash functions the compression function takes as input: a message block and a chaining value. For the very first block there is not previous "chaining value". Instead a particular value, called an initialisation vector (IV) is given. A freestart collision is a collision where the attacker can choose ...

1

Theoretically, since the domain of SHA-256 contains $2^{2^{64}-1}$ different messages and the value set only contains $2^{256}$ different message digests, there must exist at least one possible output that has more than one possible pre-image. Another important point is that SHA-256 is a deterministic function. This means that if you hash the same message ...

3

IND-CPA is equivalent to semantic security under CPA.

3

I had a similar conundrum myself when I accepted a position doing very crypto-specific engineering work in industry. They asked me what my title should be, and I didn't really know. I asked my undergrad advisor and he said, effectively, that someone who builds cryptosystems, and proves them secure in a precise way, using modern proof techniques and ...

3

Given a scenario, e.g. my Dropbox was hacked, and the hacker has access to my EncFS encrypted texts, and probably the history of it as well. Is that what was mentioned as "two or more snapshots" and "different times"? Whether it applies depends on how the storage system would work. As far as I can tell, EncFS itself has no backup/versioning capability. ...

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