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Mar
1
comment Twofish vs. Serpent vs. AES (or a combo)
The strength of the blockcipher is rarely the weakest point in a security system. There is no public cryptoanalysis that comes close to a practical break of AES. I use AES in TrueCrypt, since it's much faster than the others (thanks to AES-NI) and I consider it strong enough.
Feb
27
comment Standard serialization format for libsodium-based messages
I'd use a simple version number and concatenation outside the box and a serialization library to produce the plaintext on the inside. Since you send this for every request, I'd use some compact encoding for the message (messagepack works if the keys are short) and I'd use (urlsafe) Base64 instead of hex. Finally I'd consider HMAC, since it doesn't require a nonce.
Feb
27
revised Drawback of ElGamal encryption
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Feb
27
comment Drawback of ElGamal encryption
Upsides compared with (EC)IES style schemes: None for normal encryption. Downsides: 1) Weak security proof (DDH) 2) Annoying to implement, since you need to be able to encode as group elements 3) malleable 4) The limited message size means that you typically still need to implement hybrid encryption.
Feb
27
comment Standard serialization format for libsodium-based messages
I'd simply concatenate nonce and ciphertext.
Feb
21
comment Figure out the encryption being used
If the algorithm doesn't suck, this will be impossible. Reversing the game executable is the most promising path.
Feb
19
comment Full Domain hash library
You can always chain a hash function with a stream cipher. Or simply use the hash in CTR mode for the expansion, similar to what Skein does internally.
Feb
19
revised What is the period of a cipher?
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Feb
19
revised What are the computational benefits of primes close to the power of 2?
added 284 characters in body
Feb
19
answered What are the computational benefits of primes close to the power of 2?
Feb
19
revised Can I jettison MAC if I already have SHA1(M)?
added 322 characters in body
Feb
19
revised Idea for secure password hash-likes, is this feasible/usable/workable?
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Feb
19
comment How does BLAKE2 ensure that hash(A) != hash(B) when B = A||0 and both A & B have the same number of blocks?
A draft RFC describing BLAKE2.
Feb
19
revised Good enough deterministic PRNG based on hashes
obsolete due to migration
Feb
17
comment Pseudorandom number generators based on hard problems in mathematics
@poncho There's also "The RSA problem is hard and the hash function used to create the padding is a random oracle".
Feb
17
comment Pseudorandom number generators based on hard problems in mathematics
There is Blum-Blum-Shub, which is related to factoring. But the security proof isn't very tight.
Feb
17
comment Anonymous Gravatar Problem
@fgrieu The idea behind gravatar is associating an image with an email address. So it needs long term email addresses to function properly. A couple of years ago I recovered about 20% of email addresses on stackoverflow by guessing. Others have achieved closer to 50% using a GPU hasher, but on a different dataset.
Feb
16
reviewed Reviewed Decryption of message in IBE without random oracle using bilinear pairing registration?
Feb
16
revised Decryption of message in IBE without random oracle using bilinear pairing registration?
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Feb
15
comment SHA-512 Length Field - What is it?
Yes, it's the length of the message in bits (without padding).