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Use key services and data keys where possible for faster EC operations. - #38101
Use key services and data keys where possible for faster EC operations.#38101vcsjones wants to merge 1 commit into
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ghost
commented
Jun 18, 2020
vcsjones
commented
Jun 18, 2020
I guess what I am looking to get input on:
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bartonjs
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Things seem.... OK... though I'm confused now about what the difference is between new and old, and am curious to see if things can collapse (when I looked previously I thought they were completely parallel key types, not both SecKeyRef).
If the big difference is that now (vs when I wrote all of this) keys work without being stored in the keychain, but PFX export fails unless it's in a keychain, then I'd hope for an approach like:
- KeyGen makes only the purely ephemeral keys ("data keys"?)
- I assume creating a SecIdentityRef still requires a keychain, so CopyWithPrivateKey would need to find out that the private key doesn't have a keychain and deal with that then.
- The Get*PublicKey methods on a cert should just export the keychain-based key and return a new ephemeral key, it looks like that's always guaranteed to make the first public key usage faster, by a couple orders of magnitude.
- The Get*PrivateKey methods can opportunistically export the keychain-based key and make it into an ephemeral keypair. If export fails, use an ephemeral public key along with a keychain private key.
Assuming that all keys can go through the simpler-looking API, we'd just route them all there. If the new API isn't available on iOS, but the old one is, we can hopefully use the one signature and make it use the new API when available and the old API when required. Then all the complexities are around key->cert and cert->key, but once we have a key everything makes sense.
| { | ||
| Success => dataKey, | ||
| kErrorSeeError => throw CreateExceptionForCFError(errorHandle), | ||
| _ => throw new CryptographicException { HResult = result } |
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The unexpected error codes should Debug.Fail, then probably just throw a default CryptographicException (consistency with the existing paths).
| SecKeyPair keys = GetKeys(); | ||
| byte[] formattedSignature = AsymmetricAlgorithmHelpers.ConvertIeee1363ToDer(signature); | ||
| if (keys.PublicDataKey != null) |
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Would there ever be a situation where we can't get a public data key?
| internal SafeSecKeyRefHandle? PrivateDataKey { get; private set; } | ||
| private SecKeyPair(SafeSecKeyRefHandle publicKey, SafeSecKeyRefHandle? privateKey) | ||
| private SecKeyPair(SafeSecKeyRefHandle publicKey, SafeSecKeyRefHandle? privateKey, SafeSecKeyRefHandle? publicDataKey, SafeSecKeyRefHandle? privateDataKey) |
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What is the SecKeyRef version of the public key needed for (abstractly)? It seems like all public keys are exportable, all exportable keys can be made into data keys, and data keys are faster.
Can this pair type be a triplet instead of a quadret? PublicDataKey / PrivateDataKey / PrivateKey
| internal SafeSecKeyRefHandle? PrivateDataKey { get; private set; } | ||
| private SecKeyPair(SafeSecKeyRefHandle publicKey, SafeSecKeyRefHandle? privateKey) | ||
| private SecKeyPair(SafeSecKeyRefHandle publicKey, SafeSecKeyRefHandle? privateKey, SafeSecKeyRefHandle? publicDataKey, SafeSecKeyRefHandle? privateDataKey) |
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Actually, now I'm confused. If the existing keys were SecKeyRefs, and the new keys are SecKeyRefs, what's the difference, and why don't they interoperate?
I'm not finding the data in the docs
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It's... hard to articulate and compounded by I think there is at least one bug in MacOS that I am trying to get chased down. I'll experiment a bit and come back with a more thorough explanation of things.
Now that I have Big Sur working and runtime building on it (surprise, nothing in S.S.C broke so far) I wonder if I will still hit quirks.
vcsjones
commented
Jul 10, 2020
Going to close this for now, will make a new PR when it makes sense. |
This is an attempt at improving asymmetric cryptographic operations on macOS, starting with ECDSA.
The makes use of Apple's newer Trust / Key Services APIs instead of using security transforms. In order to gain performance increases, two things needed to happen. One, the key needed to be a "data" key, not attached to any keychain, not even an ephemeral one. Second, use the
SecKey*APIs.Though the APIs still work off of
SecKeyRefs, many of the legacy APIs cannot operate on keys that are not in a keychain, ephemeral or not. An example of this isSecItemExportfor ECDSA data keys. To keep the existing code paths working and the changes more minimal, and allow for more gradual adoption of key services where possible, both key handle types are used. When data keys are present, those are preferred for signing and verification operations.In this PR data keys exist in two scenarios. The first is
CreateorGenerateKey. The second isImportParametersand any other import methods that defer to it. Other means of obtaining a key, like from a certificate in a keychain or importing a PFX, will not have data keys and will use security transforms.The data keys are obtained by exporting the keys to
ECParametersand importing them again through keychain services APIs. This means that although signing and verifying ECDSA operations are much faster, importing and key generation take a performance hit since they have more work to do.Some native support for RSA exists here. Though none of the managed implementation uses it yet, as this is solely for ECDSA so far.
Contributes to #36107
Benchmarks:
All sign / verify benches use a generated key.
Code is here: https://github.com/vcsjones/DotNetCryptoBenches