# All Questions

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### Would this method deliver a perfectly non-malleable encryption for at least two blocks?

Say I’m using a 128 bit block cipher and would like to encrypt a 256 bit input that would be divided to two blocks, however I wish that every bit changed in the ciphertext would completely corrupt ...
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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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### Can a TLS client perform any DH regeneration?

I have only the barest understanding of cryptography, but I've been following the Logjam issue; some posts and articles (elsewhere) imply that a client can regenerate DH keys. Is Logjam solely a ...
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### Is it possible to have identical public keys for different ciphers?

Is it possible to have key pairs for two different ciphers — for example RSA 1024 and some yet to be released EC or other asymmetric cipher than uses 1024 bit keys — that have the same ...
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### Logjam on Elliptic Curves?

I think we're all aware of the Logjam attack. From now on we know that re-using primes for DH is a bad idea. But we also say that elliptic curves are safe from the attack (relying on the NFS), ...
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### Why is Bcrypt called a Key Derivation Function?

I am trying to understand why is bcrypt called a Key Derivation Function? I looked up the details of Ekfblowfish on Usenix article here: ...
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### Is Encryption without knowing the input directly possible at all?

I know the question is rather unusual, but let me clarify what I'm searching for: There is one person, lets call her $Alice$. $Alice$ has $n$ plaintexts $t_1..t_n$ and $n$ public keys $pk_1..pk_n$ of ...
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### Factorization of a number obtained by a modular multiplication operation can reveal factors of the used operands?

Consider a number $r$ obtained by: $r=a \cdot b \mod n$ Knowning the factorization of $r$ can reveal some information (bits) of $a$ and $b$ ?
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### Authenticated EC key exchange without a signing/signature scheme?

From my little understanding of EC-based authenticated key exchange protocols, I believe that it is not possible for authenticated key exchange without a signing/signature scheme. Is this correct? ...
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