Per an e-mail to public-webcrypto, ------------------ Looking at the current text, the statement ‘enc’ is equivalent to ‘enconly, deconly,wrap,unwrap’ is incorrect. The expectation is that the value of enc is to be interpreted based on the current algorithm value. Thus it would be either ‘enconly,deconly’ or ‘wrap,unwrap’. ------------------ So, it seems likely that the spec will change.
<rdar://problem/27858353>
The bug is resolved by Bug 164446.