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The parallelism was probably one reason why Argon2 won the Password Hashing Competition. The use of processor cores allows for greater memory hardness (security) without increasing the execution time accordingly. The drawback is that developers have since then been wondering what value they take for their application. Paralellisms depends on the number of ...

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Would it be safe to use an architecture-level instruction like RDRAND or RDSEED (x86) or RNDR (ARM) to generate this key material, and then derive a key that way? Would you need to derive the same key twice (for example, you're using the key to encrypt data from Alice to Bob, so both Alice and Bob need to derive the key; or if you're using the encrypt ...

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The reason why the nonces are used as key is that there are some legacy PRFs, RFC 7296 mentions two, AES-XCBC-PRF-128 and AES-CMAC-PRF-128, that use a fixed key length (128-bit in this case, so only 64 bits of each nonce are used). Any DH key exchange that produces a longer shared secret would be rendered ineffective if its output was used as key with such ...

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I understand the question to mean: is there a function $F$ whose domain is signatures under a public-key signature scheme such that, given a signature $s_1$ made with a key $k_1$ and a signature $s_2$ made with a key $k_2$, $F(s_1) = f(s_2)$ if and only if $k_1 = k_2$? Or in simple terms: can you tell who made a signature by looking at it? You aren't going ...

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While it's technically not (probably) an issue, you should definitely avoid sharing keys between different purposes. RSA uses separate keys for signing and encryption, for example, since an encrypted-and-signed message would cancel out. RSA only signs a hash of the original message, negating this issue, but it still avoids sharing keys because it's simply ...

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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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