web crypto api user report

dear fellow cryptos,

i'm new to the W3C and don't really understand the mechanisms and
procedures, and what with the web crypto API recommendation around the
corner, i realise that this message may well be very late to the game.
apologies in advance for any faux pas i may commit along the way.

i've been using crypto APIs for a long time, and so when i recently
discovered the API, i thought i would try to essentially make
standards-compliant web-hosted versions of some of my applications. this is
an account of the issues i ran into along the way, which raise some
questions that i humbly hope the community can perhaps address.

the main issue i ran into was related to (surprise) usages. if for example
i generate an RSA key pair, and happily encrypt and decrypt with it, then
export the public key, then i instantly lose its encryption capability.
this was a surprise, to say the least -- this is a *public* key we're
dealing with.

(a reply on the comments list advised me of a workaround involving removing
the key_ops and ext properties from the JWK structure, pre-import. this
presumably simulates a key from the outside world, but it has the opposite
effect - i can import for encrypt but not decrypt this way. also it does
seem a little odd that hacking the JWK structure is required for
roundtripping with different usage ramifications.)

however, the simple act of wrapping this key in a simple (ie easily derived
from consecutive numbers) AES key effectively removed the usage
restriction. this creates an odd dichotomy, where if *i* write the wrapping
code, it's not allowed, but presumably the API has its own special import
mechanism that bypasses usages.

(a similar situation occurs with private keys and the decrypt usage. i can
get around that with wrapping, too, but experience has taught me to do my
own wrapping, especially in heterogenous environments - which is not
allowed here)

another significant issue i ran into was that RSAES-PKCS1 is no longer
supported. this is unfortunate as there are a lot of such keys around. it
would have been nice if the API let me import such keys and then export
them as something "better", but the API seems to conflate keys and key
encoding.

and the last issue (for now, grin) is that it seems i can make an RSA pair
for encrypt/decrypt or sign/verify but not both. really? i remember the bad
old days in pre-Bouncy Castle JCE, where i had to have both RSA and DSA
keys due to similar artificial restrictions.

thanks for listening, and any help with these issues. if this isn't the
right place, then please advise.

best regards
Jason