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May
29
awarded  public-key
May
23
comment Google is using RC4, but isn't RC4 considered unsafe?
@PhilP: actually, with a recent enough x86 CPU (one with the AES-NI instructions), AES is vastly less expensive than RC4. Anyway, encryption speed is non-negligible only when doing bulk data transfer, which is not typical of what Google does. Most of what Google does is CPU-heavy and encryption cost is quite dwarfed by it.
May
23
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May
10
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10
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Apr
30
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Apr
26
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Apr
26
awarded  hash
Apr
25
awarded  Nice Answer
Apr
22
comment Is RSA of a random nonce with no padding safe?
@CodeInChaos: yes, my argument does not show why per-encryption randomness is required, which is why I wrote in my response "more generally". You need per-encryption randomness to avoid exhaustive search attacks on the encrypted text (which may or may not be applicable, depending on context -- it depends whether you are encrypting a meaningful message, or a random session key).
Apr
22
revised Why is elliptic curve cryptography not widely used, compared to RSA?
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Apr
22
comment Can one reduce the size of ECDSA-like signatures?
@DavidSchwartz: if you aim at 80-bit security, you still need 2^80 distinct signatures (i.e. valid for distinct messages), otherwise exhaustive search on the signature value is a break. So a signature length cannot be less than 80 bits. Algorithms which work on discrete logarithm tend to double that figure (you need a 160-bit group to achieve 2^80 resistance), so 160-bit signatures (that's what you get with BLS). Then, (EC)DSA adds its extra 160 bits, hence the 320-bit DSA signatures.
Apr
17
answered Can one reduce the size of ECDSA-like signatures?
Apr
10
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Mar
30
awarded  Enlightened
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30
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Mar
17
awarded  Popular Question
Mar
10
answered Complexity of arithmetic in a finite field?
Mar
7
answered Is it safer to generate your own Diffie-Hellman primes or to use those defined in RFC 3526?
Mar
6
answered reverse of md5sum