513 reputation
315
bio website sitewat.ch
location Teresina, Brazil
age
visits member for 3 years, 2 months
seen May 6 at 16:57

Do not trust any security related answers you see on SO. Not from me, not from anyone. There are very smart people on SO and there are excellent answers given, although the right answer is almost never chosen. Test everything, trust no one.

I have been writing exploit code for more than 5 years. I have found numerous vulnerabilities. I have received three severity metrics from the Department of Homeland Security. The most severe is in the top 500 more dangerous software flaws of all time.

My CVE numbers:

CVE-2011-0050 CVE-2011-0049 CVE-2011-0048 CVE-2009-1759 CVE-2009-0468 CVE-2009-0467 CVE-2009-0389 CVE-2008-6975 CVE-2008-6499 CVE-2008-6498 CVE-2008-5621 CVE-2008-2043 CVE-2008-2002 CVE-2007-6485 CVE-2007-6458 CVE-2007-6459 CVE-2007-6471 CVE-2007-5646 CVE-2007-0134 CVE-2007-0132 CVE-2007-0130 CVE-2006-6781 CVE-2006-6780 CVE-2006-3208 CVE-2006-3207 CVE-2006-3206 CVE-2006-3205 CVE-2006-3204 CVE-2006-3203


Feb
7
comment Is there a problem with constructing a CSPRNG using MD5 or SHA1?
+1 Great paper. The CTR_DRBG CSPRNG design looks great. Do you know of a paper that talks about keystream generators for DRBG?
Feb
4
comment Is there a problem with constructing a CSPRNG using MD5 or SHA1?
@CodesInChaos In this case, using a CRC-like function for mixing, and md5 or sha1 for the output stream.
Dec
21
comment Efficient Symmetric Mutual Entity Authentication Protocol
@Martin Lundberg if you have a "server" then you can have a "time server". I think that not having time in your current protocol is a mistake.
Dec
21
comment Efficient Symmetric Mutual Entity Authentication Protocol
@Martin Lundberg Kerberos is probably more efficient than your protocol because its doesn't use RSA. I would avoid asymmetric cryptography as much as possible. Not having an accurate clock has other problems. How do you void keys at noon when their time is up? This is why kerberos tokens have a timestamp!
Dec
20
comment What is an easy method of proving that a cryptographic oracle attack is possible?
we are the cryptographers. I think that Nathan Cooper's approach is better. Try manipulating the cipher text and look at the response. See if you can get the server to respond with a Noise Block for CBC-R or simply proving malleability by attacking the padding.
Dec
20
comment What is an easy method of proving that a cryptographic oracle attack is possible?
As a penetration tester my job is to prove that software is insecure.
Dec
18
comment What is an easy method of proving that a cryptographic oracle attack is possible?
I want the best method that that can be applied in a scientific way. If this is the best, then so be it.
Dec
5
comment Ensuring integrity of a client side script
@Barry Steyn Well people try, look at the xbox... and look at all of the pirated games for the xbox.
Dec
4
comment AES encrypting multiple files
+1 i love that scrypt paper.
Dec
3
comment What is an easy method of proving that a cryptographic oracle attack is possible?
@Paŭlo Ebermann♦ good question. The attacker, no more no less.
Oct
26
comment Does chaining random number generators lead to loss of randomness?
@Inemesit Affia that is a question for crypto.se
Aug
31
comment How is block cipher padding verified for consistancy?
+1 Great answer, but I still have some questions. There appears to be some sanity checks for null byte padding, does this also lead to a padding oracle attack?
Aug
27
comment Malleability attacks against encryption without authentication
+1 creative attack
Aug
26
comment Malleability attacks against encryption without authentication
Are you suggesting that if I replace ciphertext block N-1 with A⊕B⊕(ciphertext block N-1) I will have the message B for the plain text block N?
Aug
26
comment Malleability attacks against encryption without authentication
+1 good stuff. PKCS7 would severally undermine this attack.
Aug
26
comment Malleability attacks against encryption without authentication
How is padding checked for consistency? Do you know of a good paper that explains this?
Aug
13
comment MD5 pre-fixing with an unkown postfix
Is this a product of the prefixing attack, or is this due to the fact that this isn't an RFC'ed hmac?
Aug
13
comment MD5 pre-fixing with an unkown postfix
@fgrieu yes, you are correct.
Apr
6
comment Efficient and stateless anti-forgery method
@Ilmari Karonen Its applied cryptography, but I don't think they will help. I am asking for a new crypto design.
Aug
21
comment How long would the 100 Year Cryptography Project have secured its data had it been started 100 years ago?
@Chad Yeah but that wouldn't have been a problem if we didn't have Alan Turing on our side.