FIPS requires that any 'approved' included crypto algorithm implementations are self-tested, and pass a verification program (just a big bunch of somewhat poorly conceived known answer tests).
It also has a list of 'allowed' algorithms, which don't need to be tested but can be offered by a FIPS crypto module.
The CSPRNG used for key generation must be of an approved construction, but there are a number of choices ranging from stupid shit nobody sane would choose (Dual EC DRBG) to ones which are trivial variations on hashes, HMAC or block ciphers in OFB or CTR mode. Sadly, it says nothing about the quality or construction of actual entropy sources.
Naturally, everything not 'approved' or 'allowed' cannot be offered by a FIPS crypto module.
On the plus side, this means vendors can't offer proprietary stupid-shit like LFSR stream ciphers. Unfortunately, the approved and allowed list rarely keeps up with good quality or fixed crypto (you'll not find any eSTREAM finalists, or EdDSA, or deterministic DSA, or curve25519 ECDH, for example).
Also, the rules are pretty poorly enforced: you'll still find new FIPS certificates issued for boxes which do TLS < 1.2. This is a lie: MD5 is not allowed or approved, and is a fundamental (if conservatively used) part of the protocol in those versions.
Source: I used to make FIPS-approved HSMs. AMA? :)
A question if I may:
Could you "accidentally" make a FIPS compliant library? Assuming that the LibreSSL fork where to include ONLY the FIPS approved ciphers and hashing algorithms, it should be possible to have a library that could be passed of a compliant.
If I understand you correctly, the issue with FIPS is that you would have to be able to disable all but a subset of the features, regardless of these feature being worse or better than what is defined in the FIPS documents?
That's a bit more that one question, but I would like to know. Thanks.
It is not just that the library can only contain those specific approved ciphers and hashing algorithms, they also have to be certified through a lab, then that lab has to sign off on it (this costs thousands of dollars). You have to build in a self-test system that verifies the integrity of the FIPS components using known answer tests, and the FIPS module itself has to be able to self-check itself against a known hash, so your linker has to be nice enough to put the FIPS module at a known location (making exploitation simpler).
The whole FIPS canister thing in OpenSSL is a HUGE pain in the behind when you are building a library/product using it, and overall doesn't increase security one single bit. Yes your crypto is now FIPS 140 certified, big whoop.
[Note: I am going off the OpenSSL FIPS canister implementation details here...]
> Could you "accidentally" make a FIPS compliant library?
Let's differentiate between "FIPS compliant" and "FIPS certified".
FIPS complaint: you could get a FIPS certified product if you wanted, without changing your product.
FIPS certified: you paid NIST and a FIPS test lab some money, the lab tested your module, submitted a test report to NIST, and NIST published certificates saying that a certain version of your product (running on a particular OS and CPU architecture, for software modules) is FIPS certified.
So, yes, you could accidentally come up with a FIPS compliant crypto module. But getting certified costs actual money (last time I did it, as I recall just shy of $100k).
> the issue with FIPS is that you would have to be able to disable
> all but a subset of the features, regardless of these feature
> being worse or better than what is defined in the FIPS documents?
To some extent it depends what you mean by 'feature' here. If it's a crypto algorithm offered by your module for external use, there is quite little leeway. If it's a fundamental feature of your product that internally uses exotic crypto, you can often convince your test lab to gloss over it.
Thanks for the correction. I'm on the hardware side of things, so my understanding was that the "allowed" algorithms were actually required, and I'm relieved to hear that's not the case.
FIPS requires that any 'approved' included crypto algorithm implementations are self-tested, and pass a verification program (just a big bunch of somewhat poorly conceived known answer tests).
It also has a list of 'allowed' algorithms, which don't need to be tested but can be offered by a FIPS crypto module.
The CSPRNG used for key generation must be of an approved construction, but there are a number of choices ranging from stupid shit nobody sane would choose (Dual EC DRBG) to ones which are trivial variations on hashes, HMAC or block ciphers in OFB or CTR mode. Sadly, it says nothing about the quality or construction of actual entropy sources.
Naturally, everything not 'approved' or 'allowed' cannot be offered by a FIPS crypto module.
On the plus side, this means vendors can't offer proprietary stupid-shit like LFSR stream ciphers. Unfortunately, the approved and allowed list rarely keeps up with good quality or fixed crypto (you'll not find any eSTREAM finalists, or EdDSA, or deterministic DSA, or curve25519 ECDH, for example).
Also, the rules are pretty poorly enforced: you'll still find new FIPS certificates issued for boxes which do TLS < 1.2. This is a lie: MD5 is not allowed or approved, and is a fundamental (if conservatively used) part of the protocol in those versions.
Source: I used to make FIPS-approved HSMs. AMA? :)