# All Questions

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### Fast hashing into elliptic curve

Is there a fast algorithm for mapping $n$-bit numbers $s$ (for fixed $n$) into a cyclic subgroup of an elliptic curve (over a finite field) in which the Discrete Logarithm Problem is hard? By fast, I ...
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### Signing a document: which algorithm to use?

What I want to do is to digitally sign a document. I am new to cryptography and was wondering what issues to take into account. The only criteria is that a textual document signed should produce a ...
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### Compact digital signature for noisy data

The question asks for a signature scheme, with a public verification procedure, that is tolerant to minor alterations of the signed data during its transmission [possibly in analog form over some ...
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### Why must IV be sent with each packet?

I was reading about Encrypt-then-MAC and everywhere I go it seems people include the IV with the ciphertext generated for each message then MAC that and send all the information concatenated. Why do ...
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### Is ”generating transcripts that are indistinguishable from actual messages in a signature scheme” not universal forgery?

In the Pointcheval paper “Security arguments for digital signatures and blind signatures”, they have proved the security of Schnorr signature for existential forgery under adaptively chosen-message ...
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### Comparing two values without revealing them

Suppose Alice wants to prove to Bob that t1 is less than t2. t1 and ...
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### BigInteger in Java and Randomness

I'm looking for some PRNGs and – as I have been using Java for a long period of time – I thought that the BitInteger class, together with the ...
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### Universal Circuits in Indistinguishability Obfuscation Candidate Construction

I am currently working on an implementation of the candidate construction for an indistinguishability obfuscator that was recently proposed by Garg et al. The relevant paper can be found here. ...
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### Does this protocol provide Perfect Forward Secrecy / are there potential security flaws?

We have a HMAC key (128 bit/16 bytes) an AES key (128 bit/16 bytes) an AES IV (128 bit/16 bytes) a random salt (128 bit/16 bytes) Each packet is signed with a HMAC (SHA256) After each packet is ...