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C++, compilers, application security, tamper resistance, cryptography


Sep
24
awarded  Autobiographer
Jan
24
accepted TLS: Is Integrity assured when using NULL cipher
Jan
24
comment TLS: Is Integrity assured when using NULL cipher
ok trhanks, one of the other commenters mentioned AES hw acceleration is such that this is likely not a worthwhile optimisation and that made a lot of sense too
Jan
21
comment TLS: Is Integrity assured when using NULL cipher
CPU is arm7. I'm not worried about the handshake here, i agree with everything you say, there are things we can optimise in the handshake for sure and we need to study that too. The question applies to the communication after the handshake. Specifically, can we have integrity if there is no session encryption and is that a reasonable optimisation.
Jan
21
comment TLS: Is Integrity assured when using NULL cipher
is that acceleration done in the network hardware ? so i'd need to look at those hardware specs and check that driver implementation... this is an embedded platform.. in current tests, excluding connection / handshake, for non blocking sockets I meaure that for a given data size that TLS-DHE-RSA2048-AES256-SHA takes 3ms longer than a clear channel. E.g. clear protocol takes 300us, TLS 3300us. I'm measure that across an SSL_write to a non-blocking socket and I take the resulting time to include encryption, mac, handoff to hw but not the transmission time.
Jan
21
asked TLS: Is Integrity assured when using NULL cipher
Jan
10
comment RSA key length choice for TLS when confidentiality not important?
While we're here, is the factoring time the worst case ? e.g. if takes 100 days to factor a N bit number does that mean that the attacker has a 50% chance to find the factors in 50 days ?
Jan
9
awarded  Student
Jan
9
awarded  Scholar
Jan
9
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Jan
9
comment RSA key length choice for TLS when confidentiality not important?
Also, good point about the entropy of those devices. Is there any way to quantify that problem, what's the worst case scenario if there's poor random number generation from some of the devices on the network. I guess an attacker would determine a set of possible random numbers and brute force keys in that space.. so it comes down to is that space sufficiently small that an attacker can brute force it in the session keys lifetime
Jan
9
accepted RSA key length choice for TLS when confidentiality not important?
Jan
9
comment RSA key length choice for TLS when confidentiality not important?
that pretty much answers it - thanks. one question though, regarding the polynomial selection referred to in the factoring 768bits paper which is apparently a big chunk of the factoring effort. are the polynomials used in that paper equally useful for any 768 bit number, or does the polynomial selection effort have to be undertaken for each different number ?
Jan
9
comment RSA key length choice for TLS when confidentiality not important?
Yeha i wondered that, the polynomial selection, is that specific to a specific public key or are the same polynomials useful to all keys of that size..
Jan
9
comment RSA key length choice for TLS when confidentiality not important?
ECC could be an option but not right now for other reasons, not all the devices on the network support it. I think the same question would come up though, NIST recommendations are blanket, whereas some applications do not require the same level of protection as others
Jan
9
comment RSA key length choice for TLS when confidentiality not important?
thanks. i found this other answer too which says that rsa 512 is beyond an 'amateur' effort in 2012. security.stackexchange.com/questions/4518/…
Jan
9
revised RSA key length choice for TLS when confidentiality not important?
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Jan
9
awarded  Editor
Jan
9
revised RSA key length choice for TLS when confidentiality not important?
added 180 characters in body; edited title
Jan
9
asked RSA key length choice for TLS when confidentiality not important?