Cryptographic Right Answers

Re:Cryptographic Right Answers by lvh on Wednesday April 04, 2018 @12:14PM (#16756139)

HMAC will, hell or high water (assuming you're not doing HMAC-CRC32 or whatever :-)) give you a MAC. (It'll do slightly better; unlike, say, GMAC -- but that's a boring detail for now.)

You can shoot yourself in the foot with HMAC but it won't be because of HMAC; for example: if your messages don't contain a nonce or timestamp they might be replayable or something. But that's not an HMAC flaw.

So to answer your question: maybe? You can get in plenty of trouble with HMAC, but it won't be HMAC's fault.

[ Parent | on HN ]

Re:Cryptographic Right Answers by stouset on Wednesday April 04, 2018 @01:54PM (#16757182)

Also if you don't use an unambiguous encoding if you're signing multiple aggregated fields. Either by using field separators that can't occur in the data, or by using a format that prefixes fields with their lengths.

[ Parent | on HN ]

Re:Cryptographic Right Answers by lvh on Wednesday April 04, 2018 @02:08PM (#16757328)

Right. You can use JSON or something to get out of this quick.

[ Parent | on HN ]

Re:Cryptographic Right Answers by andrewflnr on Wednesday April 04, 2018 @03:12PM (#16757915)

Well, sure, but it's not AES's fault when you reuse nonces, either. :)

[ Parent | on HN ]