//     -   ObjectKey := DAREv2_Dec(KeyEncKey, SealedKey)
//     - object_data := DAREv2_Dec(ObjectKey, enc_object_data)
//     Output: object_data
//
// ### SSE-S3 and KMS
//
// SSE-S3 requires that the KMS provides two functions:
//
//  1. Generate(KeyID) -> (Key, EncKey)
//
//  2. Unseal(KeyID, EncKey) -> Key
//
//  1. Encrypt:
//     Input: KeyID, bucket, object, metadata, object_data
//     -     Key, EncKey := Generate(KeyID)

is different from the same C type used in another.

Any C function (even void functions) may be called in a multiple
assignment context to retrieve both the return value (if any) and the
C errno variable as an error (use _ to skip the result value if the
function returns void). For example:

	n, err = C.sqrt(-1)
	_, err := C.voidFunc()
	var n, err = C.sqrt(1)

Calling C function pointers is currently not supported, however you can