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May
28
comment Is TEA considered secure?
@user54609 8 byte blocks are annoying to use since it makes encrypting more than a GB using a fixed key problematic. In a quick test TEA was rather slow at 45 cycles per byte. Why do you claim it's "super fast"?
May
25
comment Efficiency of chaining AES “groups” of blocks
This technique is responsible for the famous BEAST attack against TLS.
May
23
reviewed Leave Open Is a Mersenne-twister cryptographically secure if I truncate the output?
May
23
reviewed Close Security assessment between $g^{a_ix_i+r_i}$ and $g^{x_i+r_i}$
May
23
reviewed Close Understanding math behind RSA key derivation
May
23
reviewed Leave Open Which concrete applications benefit from Oblivious RAM constructions?
May
22
awarded  Custodian
May
21
revised What is the purpose of update() in popular hash APIs?
added 34 characters in body
May
21
comment Which tamper-protection algorithm provides the shortest output?
@Vilx- With HMAC the chance of accepting a forgery is $2^{-n}$ for an $n$ bit MAC. With GCM every successful forgery reveals a big part of the key whereas for HMAC the only effect is that you accept a forgery. So if you really need to go below 128 bit MACs, I recommend against GCM. Another issue with GCM is that it needs a nonce and reuse is fatal, whereas HMAC doesn't need a nonce.
May
21
comment Which tamper-protection algorithm provides the shortest output?
I'd go with truncated HMAC-SHA-2 with a length somewhere between 64 and 128 bits. Truncation is fine with HMAC, but do not truncate a GCM / GHash MAC.
May
20
reviewed Leave Open how to use common modulus attack?
May
20
comment how to use common modulus attack?
Didn't realize RSA had this property. Even though this is a low effort question, +1 for making be learn something new.
May
20
revised how to use common modulus attack?
added 3 characters in body
May
19
comment Do I need two keys for AES CBC and HMAC or can I use the same key for both operations?
Related: Why can't I use the same key for encryption and MAC?
May
19
revised Cryptographic hash function for 32-bit length input keys
deleted 11 characters in body; edited tags
May
16
comment Is concatenated data hashed with scrypt vulunarable to a length extension attack?
I think scrypt inherits the zero padding length extension from PBKDF2. scrypt(s, salt) == scrypt(s + \0, salt) for short enough s shorter than 64 bytes.
May
14
comment ECDSA vs RSA: Performance on Android platform and surprising results
@user13397 My point is that the main reason for ECDSA being slow in your test is not that it's implemented in pure java, it's because the implementation has not been optimized. Native code usually results in a speedup, but a smaller one. I'd guess a good java implementation would be 50 times faster than your code and native code would result in a factor 2-3 speedup beyond the best possible java implementation. But I don't have java/android experience, so these are very rough guesses coming from my experience with writing crypto code in C#.
May
13
comment ECDSA vs RSA: Performance on Android platform and surprising results
@mikeazo It uses its own BigInteger library. But even with pure java code you can get much better performance.
May
13
revised ECDSA vs RSA: Performance on Android platform and surprising results
added 351 characters in body
May
13
answered ECDSA vs RSA: Performance on Android platform and surprising results