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revised Are partial hashes used in cryptographic protocols?
edited tags
Aug
29
comment Asymmetric algorithm for one time signing of small cleartext
What do you mean by "suited"? Standard reusable signatures like ECDSA work well for any message size and cost about 64 bytes. What improvements do you expect?
Aug
29
reviewed Approve suggested edit on Why do new versions of TLS use an explicit IV for CBC suites?
Aug
28
comment Repeatable crypto
1) AES-SIV 2) convergent encryption AKA message locked encryption AKA content-hash-key (CHK). Be sure to include a convergence secret, to avoid the confirmation and learning the remaining information attacks
Aug
28
answered Why are some key stretching methods better than others?
Aug
28
reviewed Leave Open Security of very simple XOR with random?
Aug
28
reviewed Leave Open RSA was rejected by which journal?
Aug
27
comment Is hashing a list of hashes safe?
There is one common pitfall: In hashtrees you often need to tag leaves and inner notes differently, to ensure an unambiguous tree structure. You didn't include enough context to know if this applies to your scheme as well, but I suspect that you need to use different prefixes when hashing a list of hashes and when hashing a plain file.
Aug
27
comment Is using EAX mode with a 64-bit block cipher a bad idea?
@owlstead 1) I don't get your question. In my comment I worry about birthday attacks, and D.W.'s answer confirms that the proof of security breaks down as you approach the birthday bound. So we're saying pretty much the same thing, except that D.W. wasn't too lazy to look at the details. 2) As a software guy, a cipher not being available doesn't enter my considerations. There are so many good ciphers that I certainly wouldn't bother with a 64 bit cipher, unless I specifically want one. For my taste even 128 bit blocks are a bit on the low side, I prefer 256 bit blocks.
Aug
26
comment Are variable-length crypto hash functions still susceptible to collisions?
You don't gain any collision resistance by increasing the output size beyond the capacity. A chain is only as strong as its weakest link, and the link between each consumed block is the capacity.
Aug
26
comment Partial hash code protocol for security tokens providing signatures
One link I found: community.oracle.com/thread/1751753 which mentions an APDU format.
Aug
26
answered Proving Non-Existence of ECC Backdoors
Aug
25
comment Found a way to crack AES-128, what now?
1) Consider implementing it. That way you can be sure you made no mistake and you have evidence that you're not crank. Extraordinary claims require extraordinary evidence. 2) Write a paper using LaTeX typesetting and following proper cryptographic notation and submit it to a conference or journal.
Aug
23
comment Efficiently map $2^n$ unique 64-bit vectors to $2^n$ $n$-bit vectors where $n < 64$?
@Jean You can always use a standard hash function, if the number of collisions is acceptable is for you to decide.
Aug
22
comment ECC cryptography with shorter signature when not needing high security?
@owlstead Considering that the academic ECDL record is 113 bits, a 128 curve should be acceptable for license keys. It's generally easier to crack the application, removing the key check than it is to compute that DL.
Aug
21
comment Is this a plausible PBKDF?
@esushi? Why KBKDF? This is clearly password based, not key based.
Aug
21
comment ECC cryptography with shorter signature when not needing high security?
The shortest usable signatures I know are BLS at twice the security level in size. You can truncate a few bits, raising the verification cost exponentially. Even if you'd use a 112 bit curve (which matches the largest academic ECDL break) this only goes down to about 90 bits.
Aug
21
revised Is this a plausible PBKDF?
edited title
Aug
21
comment Is this a plausible PBKDF?
Please include a compact description using mathematical notation or pseudo code instead of long c code full of unnecessary details.
Aug
20
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