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Issues with the question first: Security is not something you can duct tape on to anything you want after the fact. You can never increase information entropy by processing data. It can be kept constant or decreased depending on whether you are doing a lossless or lossy tranformation. HASH("secret"+"public") is not necessarily secure for all crypto-hash ...


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SpookyHash is clearly designated by its authors to be a non-cryptographic hash. In the cryptographic world there is simply no room for semi-broken at this level. Either there is some kind of margin to reach, say 128 bit security level or there isn't. This means that it should stand up to the current known attacks and that the design conveys enough piece of ...


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Given a set of (unhashed) Lamport signatures using the same key, an attacker can trivially forge a signature for any message whose $k$-th bit, for each $k$, is equal to the $k$-th bit of at least one of the signed messages. For example, let's say I know the Lamport signatures for the following 16-bit messages using the same key: $$ m_1 = 0001111101110001 ...


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Yes, there does happen to be such a scheme: the Lamport one-time digital signature. The basic idea of a Lamport signature is that the private key consists of a large number (say, 256) of pairs of secret random numbers, while the public key consists of the cryptographic hashes of those numbers. To sign a message, you first hash it down to 256 bits, and ...


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As both of us recently learned, the public key signature hash algorithm is negotiated completely separately from the MAC algorithm. DSA and RSA use SHA-1, ECDSA uses SHA-2, and Ed25519 uses, um, Ed25519. I'm skeptical that SSH crypto performance will be a serious issue for you. I suspect you would have to be transferring a lot of data on a really bad CPU ...



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