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bio website en.wikipedia.org/wiki/…
location United Kingdom
age 26
visits member for 3 years
seen Oct 20 at 16:03

Pentester, ex-developer, security researcher, reverse engineer, electronics tinkerer, internet activist, zombie eradicator, promulgator of useless facts, shrubbery inspector, bacon aficionado.

Strengths: Security, Crypto, Win32 API, C#, .NET, PHP, x86 assembly

All answers and comments are encrypted with ROT256-ECB.

Opinions are my own. Advice provided with no warranty.


May
23
comment Is it secure to use the hash of key as the IV in AES encryption?
A solution to this is to store a random IV in the file header, xor'ed with the hash of the password. When you decrypt, compute the password hash and xor against the stored value, then use the result as the IV. This gives you a safe way to store the IV, and a unique IV per file.
May
23
comment Order of cascaded ciphers
Just for reference, if someone sees this answer in future and wonders what custom hardware could crack DES, it's COPACOBANA: copacobana.org
May
23
comment What is the time complexity of the RC4 encryption & decryption algorithms?
Keep in mind, though, that time complexity is practically meaningless as a measure of speed in this sense, because it tells you nothing about how fast the cipher is. If it always takes 10 milliseconds to encrypt a block in a cipher, it's O(n). If it always takes 10 minutes to encrypt a block in a cipher, it's still O(n).
May
23
comment What is the time complexity of the RC4 encryption & decryption algorithms?
Most block ciphers will be O(n) against the number of blocks, yes.
May
23
asked Hash decrypts key, key decrypts cipher… why?
May
23
answered What is the time complexity of the RC4 encryption & decryption algorithms?
May
23
comment Order of cascaded ciphers
@PaŭloEbermann This is purely theoretical, so I'd be interested in the security implications of both.
May
23
comment Order of cascaded ciphers
Interesting. So the optimal solution is to place the two strongest ciphers on the outside? i.e. first and last.
May
22
revised Order of cascaded ciphers
added 69 characters in body
May
21
accepted Security of simple xor and s-box cipher?
May
21
awarded  Scholar
May
21
accepted Is a book cipher provably secure?
May
21
accepted Desirable S-box properties
May
21
asked Order of cascaded ciphers
May
2
awarded  Teacher
May
1
answered Practical necessity of semantic security under chosen plain text attack (CPA) in CBC mode
Nov
24
comment Is a book cipher provably secure?
Interesting. Given an attacker with moderate resources (i.e. one that doesn't have access to the entire world's literature) it seems that it would be secure as long as the pages, lines and letter offsets were chosen with reasonably random distribution.
Nov
24
comment Is a RSA-signature of some identifying data a safe way to implement a license key?
@MichaelKjörling - I misunderstood the intent of your response. The product ID is designed to identify the use of a particular license on a particular machine. A fresh re-install on the same machine with the same key and exact same hardware will not produce the same ID, because it's considered a separate install of that license. On a mass license, however, the product ID will be the same regardless of the hardware it runs on. Using the product ID of the OS as a basis for any security mechanism is flawed at best.
Nov
24
revised Is a book cipher provably secure?
edited title
Nov
24
revised Is a book cipher provably secure?
typo