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Jun
21
comment What's the GCM-SHA 256 of a TLS protocol?
I created this answer because the existing answer doesn't explain that the PRF and GCM should be seen as separate entities. For a general rundown of the ciphersuite components I think Stephen is right to point to the relevant Q/A on the security site
Jun
21
comment What's the GCM-SHA 256 of a TLS protocol?
@StephenTouset Upvoted comment (and created answer with similar comment). Better use the share button on any question you want to point to though. If the title changes your link may become obsolete.
Jun
21
answered What's the GCM-SHA 256 of a TLS protocol?
Jun
21
comment What's the GCM-SHA 256 of a TLS protocol?
I'm sure that 6. is incorrect. Although the same hash function may also be used for the signature, I'm pretty sure that the acceptable hash algorithms are communicated differently (i.e. using extensions).
Jun
21
comment What is Polymorphic encryption?
+1 before the question closes. This however seems to be rather different than polymorphic encryption.
Jun
20
comment CMSS key sizes flexiprovider
" but in your paper these values are 46 and 1900 bytes" who's paper would that be?
Jun
20
comment How to show the inner workings of ECC?
It isn't really possible to "cipher" actual information using ECC (I'm presuming you mean encryption/decryption here). I would show how ECDH works and then explain that this can be used to encrypt data as well (through ECIES).
Jun
20
comment Turning a 64 bit block cipher into a 128 bit block cipher
@Seth Do I read this correctly? Could I do with a 2 round Feistel network to achieve a doubling of the block size, with the restriction that I should not use the block cipher for anything else?
Jun
19
comment Why are there only positive value points on an elliptic curve?
Ah sorry, I was wrongfooted by some of the comments.
Jun
19
comment Concerns about use of MAC in my specification
@fgrieu Interesting attack, yes. It would still take way too many messages I agree, but better be safe and either use the random IV or AES-256 (increasing the key space to impossible ranges would mitigate against this attack, only requiring a small slow down). Then again, the only reason not to calculate the IV is a small speedup.
Jun
19
comment Why are there only positive value points on an elliptic curve?
Thank you for sharing your results, I've upvoted. It would however be a very good idea to accept Poncho's answer.
Jun
19
comment Session key Exchange, some doubt
From wikipedia: "Pre-shared keys may be more convenient from a key management point of view. For instance, in closed environments where the connections are mostly configured manually in advance, it may be easier to configure a PSK than to use certificates. Another case is when the parties already have a mechanism for setting up a shared secret key, and that mechanism could be used to “bootstrap” a key for authenticating a TLS connection."
Jun
18
comment Session key Exchange, some doubt
I don't know how much help you want in that case. Studying existing protocols is really helpful. RSA encryption can indeed be used and is probably easiest to implement, but you could take a look at NIST SP 800-56A for the various Diffie-Hellman key agreement options. Wishing you good luck with that may be in order though, it gets a bit technical.
Jun
18
comment Session key Exchange, some doubt
So you could also use the same authentication protocol as a TLS handshake with PSK (pre-shared key) for authentication on top of the other ones...
Jun
18
comment Encrypt-Mix-Encrypt: Full Diffusion?
+ a single encrypt between that. Not a problem for disk encryption but if the resulting block size is small then you may still have an issue.
Jun
18
revised Turning a 64 bit block cipher into a 128 bit block cipher
added 44 characters in body
Jun
18
comment 3DES over Galois Counter Mode (GCM) for authenticated encryption
@SOJPM Turned that into a question, I couldn't directly come up with the answer myself. There may be an answer in FPE, we'll see.
Jun
18
asked Turning a 64 bit block cipher into a 128 bit block cipher
Jun
18
comment 3DES over Galois Counter Mode (GCM) for authenticated encryption
@SOJPM I would rather think of a method to combine two blocks to create a block size of 128 bit instead, I've got an inkling of a feeling that using a block size and polynomial of 64 bit will break down the security to unacceptable levels.
Jun
18
comment Concerns about use of MAC in my specification
Other cheats: use IV=0, the encryption key differs each time anyway. Use an AEAD cipher such as GCM and remove everything but the nonce generation and the PBKDF.