2,520 reputation
524
bio website touset.org
location San Francisco, CA
age 30
visits member for 2 years, 1 month
seen 11 hours ago

Cyclist. Rubyist.


May
5
comment How do I produce a stream of secure random numbers from AES-Counter mode?
"So I know I have done it properly." As long as you're only considering an extremely narrow definition of "properly" that discounts timing attacks, paging virtual memory containing secrets to disk, buffer overflows, and other similar implementation faults. Producing the correct output isn't the only thing required of a cipher implementation.
May
1
comment PRF and hash functions
You should not be using a PRF to create secret keys. You should be using an RNG or CSPRNG, which may be built out of a PRG.
May
1
comment Accelerated hashing on consumer-grade CPU?
BLAKE2b is about as close as you can get to a modern hashing algorithm that's CPU-accelerated.
Apr
30
awarded  Custodian
Apr
30
reviewed Reopen Pseudocode for constant time modular exponentiation
Apr
30
reviewed No Action Needed Relative security of a Vigenère cipher
Apr
30
reviewed Close how to use salt to sign a message and how is it effective?
Apr
30
reviewed Leave Open An example of Knapsack Cryptosystem cracks/attacks?
Apr
30
awarded  Custodian
Apr
30
reviewed Leave Open How do you test the security of your cipher?
Apr
30
comment How do you test the security of your cipher?
Sorry, I figured it was obvious through context. It's true though that he won't receive a notification without addressing him directly.
Apr
30
comment How do you test the security of your cipher?
An implementation of a cipher is a different beast entirely. Even assuming a cipher with mathematically proven properties, any implementation itself is virtually guaranteed to be imperfect. Not just that it may have weaknesses (e.g., timing attacks) or bugs (e.g., overflows), but also problems with how it's used (e.g., does it mlock() memory to avoid swapping? Does it clear memory of secrets as soon as possible?
Apr
30
comment How do you test the security of your cipher?
You have professional cryptographers be unsuccessful at breaking it over the course of several years.
Apr
24
comment Is HMAC necessary if the AES ciphertext of a message includes the CRC of the message?
Also, this hasn't mentioned yet, but consider MD5 dead. It has been catastrophically broken for many years now, and should no longer be used in any cryptosystem.
Apr
24
answered Using beginning of TLS ecnrypted data to reveal secret
Apr
22
comment Is less security required for a short stream cipher than for the AES enciphering of very long messages?
You might know it will be free of intentional backdoors. But you're trading that off for the overwhelming probability of multiple unintentional trivially-exploited catastrophic vulnerabilities.
Apr
21
revised Leaving authentication data blank less secure for AES GCM?
added 4 characters in body
Apr
21
answered Leaving authentication data blank less secure for AES GCM?
Apr
18
comment Using Stream Cipher as CSPRNG
Ah, great point. Thanks for the correction.
Apr
18
comment Using Stream Cipher as CSPRNG
Yes, there absolutely is. Cryptography is hard, and if you believe it's a simple exercise to write secure code to a public spec, you're in for a bad time. Established companies with huge security teams like Amazon, Google, and Facebook can get details wrong. The notion that a developer with no cryptographic background working solo will do a better job is laughable.