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Dec
17
answered Authentication mechanism for low memory, low computing power device
Nov
29
awarded  Teacher
Nov
28
answered Authentication using certificateless signature
Oct
24
awarded  Supporter
Oct
12
awarded  Scholar
Oct
12
comment Why does NaCl's crypto_secretbox for xsalsa20-poly1305 require the first 32 bytes to be zero?
Thanks, I was missing that it was using that for the poly1305 key.
Oct
12
accepted Why does NaCl's crypto_secretbox for xsalsa20-poly1305 require the first 32 bytes to be zero?
Oct
12
asked Why does NaCl's crypto_secretbox for xsalsa20-poly1305 require the first 32 bytes to be zero?
Jul
4
comment Why restrict nonce/IV and counter to specific sizes?
With a 16 byte nonce/counter, the upper 8 bytes would only increment after 2^64 bytes (where 8/8 would wrap and collide). Are you saying that if the full thing is random (8 digits total to illustrate), I might get 10010000 and 10009999 (collides after 1 byte), but with a 4/4 split, the 9999 would be truncated to 0 and they would start at 10010000 and 10000000 and wouldn't collide until the 10000th byte?
Jul
4
comment Why restrict nonce/IV and counter to specific sizes?
But in order for the difference between nonces to be within 1000, it would mean the first 118 bits of both random nonces would need to be the same (128 - log2(1000) = ~118 bits). If that were the case then using a smaller nonce portion (e.g. 8 bytes) would hit that case much more frequently because only the first 64 bits would need to match (54 fewer bits of uniqueness) since the remaining counter bits would be 0. Or is there something I'm missing?
Jul
4
comment Why restrict nonce/IV and counter to specific sizes?
Thanks for the response. Regarding two nonces/IVs having a difference of 1000/etc, wouldn't reducing the random nonce portion (and initializing the counter portion to 0) increase the probability of having a small difference due to the smaller nonce space?
Jul
4
comment Why restrict nonce/IV and counter to specific sizes?
I didn't mean to imply an 8 byte nonce, 8 byte counter was a requirement. I've just noticed it's common for specs to recommend a split like that (or 12/4) and I wasn't sure why.
Jul
3
awarded  Student
Jul
3
asked Why restrict nonce/IV and counter to specific sizes?