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 Yearling
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Mar
12
comment How long can X.509 certificate chains be?
I think the main problem here is that a sub-CA certificate can't say "this sub CA is only certified to create certificates for (subdomains of) domain xy" or similar. That would make many problems go away, and allow longer chains without problems.
Mar
4
comment Is it possible to detect security breaches as a user before they're announced?
There are some parsers that treat the + as a space (like URL escaping), which might cause your "truly genius" problem. (I had once a mail provider, whose web interface didn't accept those + addresses as receivers, I assume for that reason.)
Feb
26
comment What prevents me from buying a SSL certificate for a domain I don't control?
Of course, for each of the four ways of verifying ownership, you just have to control the CA's internet connection to fake the ownership.
Feb
12
awarded  Yearling
Jan
7
revised How quickly can these password schemes really be beaten?
highlight lower entropy for many passwords, mention that PBKDF needs a base algorithm
Dec
2
comment Is there any legitimate reason to install yourself as a root CA?
@IanRingrose ... or just don't let the public name server resolve the name.
Nov
30
comment Have weaknesses in SHA-1 and MD5 ever actually been successfully used in an attack?
Security as a password hash is largely independent from security as a general hash (collision resistance is irrelevant for passwords, slowness is relevant).
Oct
9
awarded  Good Answer
Sep
2
comment Why should I choose SHA (such as SHa-512), instead of bcrypt or PBKDF2, for FIPS-compliance?
@kasperd While hashing (and salting) is surely better than storing the data in plaintext, it is not that much better for the average user. When attacking a single user (and known salt + hash), the cost of brute-forcing the password is about the same as using a non-salted hash (or about doubled if salt + password are together longer than one block of the hash function, while the password alone fits in just one block). Introduction of a salt just helps against untargeted attacks (i.e. those attacking many users at the same time), or attacks utilizing a pre-made rainbow table.
Sep
1
comment Why should I choose SHA (such as SHa-512), instead of bcrypt or PBKDF2, for FIPS-compliance?
@kasperd the problem is that the border between mediocre and strong passwords (when using the definition "strong is secure when hashed with SHA-512") is in a region where common humans are not capable of memorizing them (quite more than the 44 bits of entropy in the famous xkcd comic). When it can't really be memorized, I would not call it "password" anymore.
Jul
22
awarded  Caucus
Jun
14
comment Why do we have such big keys?
Note that those columns don't mean "for use by", but "to be secure agains that type of attacker". Individuals don't want to be secure just against other individuals.
May
10
comment Are open wireless networks unencrypted?
Just a technicallity: POP3 is for receiving mail, not for sending. (Though it might use the same password.) Sending is usually done by SMTP.
May
3
comment Why are MD5 and SHA-1 still used for checksums and certificates if they are called broken?
I would count file integrity as "second preimage" when an attacker is unrelated to the original author, and "collision" when the original author is collaborating.
Apr
23
comment Why can't you work backwards with public key to decrypt a message?
You don't need just a one-way function (like a hash function), but usually a trap-door one-way function. (Also, you don't need them just to exist, but actually that the function you are using one is one.)
Apr
20
comment Should I use a Certificate Revocation List?
@user3765109 You can use commercial CAs even with non-browser clients. Either you can access the system's list of trusted CAs (if there is one), or include the needed root CA(s) in your software (assuming you are controlling the client).
Apr
6
comment What's the safest way to transmit a message to another client through a server hidden from high level malicious users?
Ah, I understood that you want to whisper on an airplane.
Apr
6
comment What's the safest way to transmit a message to another client through a server hidden from high level malicious users?
I would not count on the NSA not also having a copy of my DNA, even more if I'm Edward Snowden or his son.
Apr
6
comment What's the safest way to transmit a message to another client through a server hidden from high level malicious users?
I don't see how the airplane helps here.
Mar
30
comment Can 'cracked' product keys harm the user in any way?
Using a product key for encryption of user data is a bad idea – it means that the company can also read this user data.