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awarded Notable Question
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comment Why is it wise, from a security POV to have sessions expire?
Possible duplicate of Does a session time out make an app more secure in a A+ HTTPS / random session key?
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answered In some situation can be dangerous to echo command (e.g. rm -rf *) using a script?
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revised How can I check if someone tampered with the CCTV footage or system?
updated link
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awarded Yearling
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2018
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awarded Nice Answer
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comment Modular Arithmetic problem
@avisekmanna No, it's PT=(CT-K1-K2) mod n. First, CT, then the key or keys. Indeed, if you consider K=K1+K2 as a single key, applying the formula I wrote in my answer you have PT=(CT-K) mod n, which is (CT-(K1+K2)) mod n or, equivalently, (CT-K1-K2) mod n.
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revised Modular Arithmetic problem
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answered Modular Arithmetic problem
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awarded Good Answer
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comment Why are PRNG in programming languages not cryptographically secure by default?
@EllaRose yes, AES-CTR with AES-NI is fast (I said "typically"). But crypto tools are still harder to implement than standard software. For example, you may need to reseed/rekey. No security mechanism is perfect, and if a flaw is eventually found in AES-NI that allows practical side channel attacks, you may want to deal with it somehow (or wait for the upgraded instruction set to come). Also, there are still legacy devices which don't include AES-NI. Do you think everybody follows updates, especially at such a low level, or throws devices away? All these issues don't apply to regular PRNGs.
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