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The first rule of security is: you do not invent security protocols.

The second rule of security is: you do not invent security protocols!

The third rule of security is: if this is your first time with security you do not invent security protocols.

Inventing, modifying, tweaking, hacking, extending, optimizing, or just about anything else you can do to a cryptographic protocol, hash, algorithm, PRNG, key agreement, or cryptographic technique is a very bad idea.

(Not dead.)


Jul
7
awarded  Quorum
Jul
6
revised Is NTP vulnerable to DNS poisoning or spoofing attacks?
changed mitigation from IPSec to NTP shared secret or autokey, thanks nealmcb
Jul
6
revised SCADA Operating System & Security Exploits
added 112 characters in body
Jul
6
comment Is NTP vulnerable to DNS poisoning or spoofing attacks?
@nealmcb good point. I was think of protecting the system and forgot about the built-in authentication, which is quite funny since my initial responses to the question were advertising the protocol's authentication capability. I need to think again about packet delays. Which mitigations seem dubius, all of them?
Jul
6
answered SCADA Operating System & Security Exploits
Jul
6
answered What security risks exist in cell phone apps' data transfer?
Jul
6
comment Is NTP vulnerable to DNS poisoning or spoofing attacks?
@D.W. edits made, removed opinion of protection worth, removed user detection.
Jul
6
revised Is NTP vulnerable to DNS poisoning or spoofing attacks?
added 3326 characters in body
Jul
5
comment Is NTP vulnerable to DNS poisoning or spoofing attacks?
@bruno-rohee The answer only talks about the protocol, not the implementation. I agree that the implementation is more important than the protocol, but no implementation seems to be mentioned here.
Jul
5
comment DUKPT - how does the receiver verify the transaction counter?
Could you post a link to the specification? I am not familiar with ANSI X9.24, but on cursary reading I think you are correct that the HSM must store the KSN. Transaction counters are used to mitigate replay attacks where an adversary captures a transaction and resends the same data from one party in the transaction. Prohibitions on keeping state are usually to mitigate information leakage or prevent short-cycling a protocol. I can not think of a good reason not to store the KSN as it a function of the device’s unique identifier, and the device's internal transaction counter.
Jul
5
comment Hashed passwords - How many variations of rainbow tables?
Did you search for 'rainbow tables' before asking your question? Possible duplicate of What are rainbow tables and how are they used?
Jul
4
comment Warn about specific CA in Firefox
Thanks, now I understand.
Jul
4
comment Is it a bad idea for an information holder to e-mail a user their password?
additionally... The senders are sending security critical information in response to a non-security event. They are trading security risk for business risk (loosing users).
Jul
4
comment Is it a bad idea for an information holder to e-mail a user their password?
Why do you think it is likely that the password is stored unencrypted? Because they are using poor security practices? Nice reference to an actual attack based on the OPs concern.
Jul
4
comment Is NTP vulnerable to DNS poisoning or spoofing attacks?
@nealmcb Yes, difficult. Most systems have time displayed to the user, and use of NTP typically modifies the time displayed to the user. A significant change in time would become obvious to a user. Some systems rarely have users login, and those will not be protected by user observation. However, these system are often involved in networked periodic events (SNMP status checks) and automated administrative tasks (backups). I believe it likey that significant time discrepency would be notice during these activities. So maybe it is more a question of how long until a discrepency is detected.
Jul
3
comment Is NTP vulnerable to DNS poisoning or spoofing attacks?
No, the NTP protocol (I don't know about specific implementations) has had server authentication since version 2. See Network Time Protocol, Version 2, Specification and Implementation, Appendix C. Authentication Issues
Jul
3
answered Is NTP vulnerable to DNS poisoning or spoofing attacks?
Jul
2
comment How can IT audit for installation of IIS Express?
I love your answer, now how do I convince management to do this?
Jul
1
comment Is a rand from /dev/urandom secure for a login key?
Good answer, nice coverage of the whole question including the cookie aspect. Instead of checking the random value against other random values, use a chi-square test to check the output of the generator. Fourmilab has a program ent which test the entropy of a generator and includes the chi-square test.
Jul
1
revised What to transfer? Password or its hash?
added spaces to make < known correct password > and < known correct password > visible