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Jul
26
comment Reversing DJB2 Hashes
... why are you doing computations mod 33? $\;$
Jul
26
revised Why must we hash lot of times in rainbow tables?
improved grammar
Jul
24
comment Rainbow table for DES with all-zero plaintext?
eprint.iacr.org/2005/207 $\:$ eprint.iacr.org/2006/127 $\;\;\;\;$
Jul
24
comment Is MAC-then-encrypt with stream ciphers secure?
The problem is 1; an attacker must never see authenticated plaintext. $\;$
Jul
24
comment Is MAC-then-encrypt with stream ciphers secure?
You assumed too much. $\:$ (There's really nothing else to say.) $\;\;\;\;$
Jul
24
comment Rainbow table for DES with all-zero plaintext?
See page 6. $\;$
Jul
24
comment Why is MAC using nonce+message+hash(nonce+message+identifier) not the standard?
@otus : $\:$ If "message" means plaintext rather than ciphertext, then that's right. $\hspace{1.67 in}$
Jul
24
revised Is there a generic attack on encrypted CRC32 when used as a MAC?
added an attack that uses less resources
Jul
24
comment Is there a generic attack on encrypted CRC32 when used as a MAC?
Also, since the CRC computes over headers as well, "plaintexts" from four comments ago should be interpreted as "header/data pairs". $\;$
Jul
24
comment Is there a generic attack on encrypted CRC32 when used as a MAC?
@Antikithira : $\:$ Do the outputs distinguish between invalid padding and invalid CRC? $\hspace{1.3 in}$
Jul
24
comment Different padding rules for Merkle-Damgard and Keccak/sponge function
... by their length and probably also by what they start with. $\;$
Jul
23
comment Why is MAC using nonce+message+hash(nonce+message+identifier) not the standard?
Let us continue this discussion in chat.
Jul
23
comment Why is MAC using nonce+message+hash(nonce+message+identifier) not the standard?
@Joshua : $\;\;\;$ Should your comment have "the MAC becomes" instead of "MAC is"? $\:$ I can't figure out how to parse what you wrote. $\;\;\;\;\;\;\;$
Jul
23
comment Why is MAC using nonce+message+hash(nonce+message+identifier) not the standard?
@otus : $\:$ I just edited in an example. $\;\;\;\;$
Jul
23
revised Why is MAC using nonce+message+hash(nonce+message+identifier) not the standard?
gave an example
Jul
23
comment Why is MAC using nonce+message+hash(nonce+message+identifier) not the standard?
It's a "just do it" construction that I'll describe later. $\;$
Jul
23
answered Why is MAC using nonce+message+hash(nonce+message+identifier) not the standard?
Jul
23
comment Why is MAC using nonce+message+hash(nonce+message+identifier) not the standard?
If the plaintext message had been modified, then a secure MAC would be overwhelmingly likely to catch that. $\:$ However, there exist encryption schemes such that one can easily modify a single ciphertext so that whether or not that modifies the plaintext depends in a predictable-and-useful way on what the plaintext message was. $\;\;\;\;$
Jul
23
comment Why is MAC using nonce+message+hash(nonce+message+identifier) not the standard?
... where "it" is ...? $\;$
Jul
23
comment Secure way to store fixed size string of digits
Should the data about the user otherwise stay private? $\:$ What is the size of your strings of digits? $\hspace{.5 in}$