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bio website github.com/CodesInChaos
location Frankfurt, Germany
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visits member for 3 years, 6 months
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Jan
6
comment Is Curve25519-java secure?
As far as we know, Curve25519 itself is secure. But Curve25519 as specified by Bernstein only supports key-exchange, not signing. For signing I recommend using the related Ed25519 instead.
Jan
6
revised In this example, which is a premaster secret, and which is a master secret?
[Edit removed during grace period]
Jan
4
comment Deterministically combine more than one source of entropy
can't you just hash them and map the hash to 0..1?
Jan
4
revised Can we ensure the security of a crypto-algorithm and -implementaton against acoustic cryptanalysis?
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Jan
4
comment Can a salt for a password hash be public?
Salts aren't there to prevent pre-computation. They prevent multi target attacks. Rainbow tables are one particular example of multi target attacks, and a rather useless one.
Jan
3
revised Where does the $\varphi(n)$ part of RSA come from?
added 3 characters in body
Jan
3
comment Usability of padding scheme in blinded RSA signature?
Padding adds a redundancy of a particular form. A random value almost certainly doesn't have that form and is rejected.
Dec
26
reviewed Approve accumulators tag wiki excerpt
Dec
26
reviewed Approve key-schedule tag wiki
Dec
26
reviewed Approve key-schedule tag wiki excerpt
Dec
26
reviewed Edit quadratic-residuosity tag wiki excerpt
Dec
26
revised quadratic-residuosity wiki excerpt
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Dec
26
reviewed Edit quadratic-residuosity tag wiki
Dec
26
revised quadratic-residuosity wiki description
deleted 1 characters in body
Dec
26
reviewed Approve accumulators tag wiki
Dec
26
comment Security Level Estimate when Cascading/Compositing Ciphers?
Nowadays the reason for cascading is guarding against cryptoanalytic advances against one primitive ensuring that the whole system is as secure as the strongest primitive. It's not a good way to raise the security level.
Dec
25
comment Off-the-record communication
@RickyDemer Different browsers and operating systems render text differently which leads to line breaks at different points. For example I'm using Opera, and all of your answers/comments contain large spaces in inappropriate places. Html is a dynamic format where you can't control the output precisely, unlike say PDF.
Dec
24
comment Can we ensure the security of a crypto-algorithm and -implementaton against acoustic cryptanalysis?
@PaŭloEbermann I haven't looked for one yet, since I'm mostly using ECC. But it shouldn't be too hard to write one. mpz_powm_sec from GMP has a promising description, but I didn't look into the details.
Dec
22
comment Can we ensure the security of a crypto-algorithm and -implementaton against acoustic cryptanalysis?
Didn't investigate the details, but does the attack still work with standard constant time code? These techniques cost a bit of security but not that much. (no secret memory access, always executing the very same instructions, only with different data)
Dec
22
comment Forgery Attack Against RSA Digital Signature
First of all, I want to emphasize that this is textbook RSA, not RSA as it's used in practice. For real RSA signatures an important step of signing is a collision resistant one-way hash. When using such a scheme, finding a message for a given x is practically impossible.