# Tag Info

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All block ciphers leak information. The more data that's encrypted the more data that is leaked. While as @Marc notes re-use of an IV is problem, even encrypting a single very large stream with a single key/IV where there is no possibility of re-use of the IV (e.g. properly implemented CTR mode) will leak data. It was long thought that CTR mode didn't ...

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Most symmetric encryption techniques use an $\text{IV}$. An important characteristic is that the $\{key, IV\}$ pair must never be reused. The $\text{IV}$ is randomly generated for every use, and some cipher modes (eg: GCM) break it down into one part for the nonce, one part for the counter. eg: for a 128 bit $\text{IV}$, the nonce is 96 bits, the counter is ...

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If you measure the number of keys you can guess per second (as suggested in the comments) you can calculate from there. As a frame of reference, if you can calculate 1,000,000,000,000 (1 trillion) keys per second, the time to break a 64-bit key would we an average of 15.25 weeks (106.75 days), with the longest possible time to break being 30.5 weeks (213.5 ...

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Using a Diffie-Hellman key exchange is best using keys generated on-the-fly. The reason comes down to a historical issue... Let's say we contact a web server. The server uses the key pair $S_{pub},S_{pri}$, and out client uses key pair $C_{pub},C_{pri}$. If the web server never changes its key pair, and we don't either, the handshake will always yield the ...

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No, there is no way (secure or otherwise) to compress a random $192$ byte value into something smaller; it is impossible to encode $2^{8 \times 192}$ bit possible settings in only 32 bytes (or $191$ bytes, for that matter...) Some exceptions: If those 192 bytes were nonrandom, that is, the vast majority of those 192 bit settings were impossible, you may be ...

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It took me a bit to understand your issue. In summary, you want to use your passwordstore password manager on multiple devices, without copying the private pgp keys to multiple devices. Yes, it can be done. You need to create a separate key for each device, and configure your store to encrypt the passwords to multiple keys. If you follow the steps at https://...

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Regarding your understanding You mostly have things right, but not completely. a password is a (preferably) mnemonic string that is fed into a function that generates a much longer and complex string that nobody knows, the user included. The encryption key is what is actually used to encrypt and decrypt a file. This is true apart from “preferably mnemonic”....

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A cryptographic key is a string of bits. For example, AES-128 uses 128 bits, each one of them being either 0 or 1. To be able to encrypt or decrypt, each one of those 128 bits must be set correctly. This key is the input to the encryption algorithm. For AES-128 it has to be exactly 128 bits - not more nor less. For humans, remembering 128 bits (= 16 bytes) ...

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The symmetric encryption algorithms require keys with good entropy. Usually, humans tend to have passwords with bad entropy then they are crackable There are well-known cracker programs like John the Ripper and hashcat, and rainbow tables. Today, we have better password mechanisms like Dicewire so that the entropy of the password can be much longer. In any ...

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