On 6/8/2020 1:42 PM, Valerie Peng wrote:
"md instanceof Cloneable && md is not from PKCS11" is not entirely
precise. What I mean is that for MessageDigestSpi impls from PKCS11
provider, we will need to call the clone() to know for sure whether
cloning is supported. If we decide to employ these extra logic for
saving clone() call, it's better to do it inside the
MessageDigest.of(...) so the callers don't have to repeat the same
logic. Comments?
It sounds like a good idea to me if the repeatedly checking could be avoid.
Xuelei
Valerie
On 6/8/2020 1:34 PM, Valerie Peng wrote:
Hmm, I checked all MessageDigestSpi impls of JDK providers... The
story is more complicated than we expect.
For SUN provider which implement the digest spi, implementing
Cloneable means it supports clone functionality.
However, for SunPKCS11 provider which wraps native PKCS11 library, it
always implements Cloneable interface, but when clone() is called, it
will then perform the equivalent PKCS11 calls and throw CNSE if any
PKCS11 error is observed.
So, there is a possibility that the instanceof check and the clone()
check leads to different result in this particular scenario.
The chance of 3rd non-PKCS11 party provider whose
MessageDigest/MessageDigestSpi impl implements Cloneable but throws
CNSE when clone() is called should be very low? So, I think it should
be sufficient to use "md instanceof Cloneable && md is not from PKCS11"?
Valerie
On 6/6/2020 9:10 AM, Xuelei Fan wrote:
As the the Delegate class takes care of the Cloneable SPI
implementation, it should be sufficient to use "md instanceof
Cloneable" only. It is not a expected behavior that a provider
implements Cloneable but does not really support it.
Xuelei
On 6/5/2020 10:54 PM, Weijun Wang wrote:
Is it possible to try "md instanceof Cloneable || md.clone()
returns"? Hopefully this is fast enough in most cases and also has
the chance to recognize more actually-cloneable ones.
I'm also OK with simply using "md instanceof Cloneable".
--Max
On Jun 6, 2020, at 12:02 PM, Valerie Peng <valerie.p...@oracle.com>
wrote:
I am merely following the spec's recommendation of trying the
clone() for cloneability check.
If you both are ok with it and prefer the instanceof check, I can
sure reverting back the changes in HmacCore and HandshakeHash classes.
Valerie
On 6/5/2020 2:04 AM, Seán Coffey wrote:
I share the same concern. clone() is a heavy weight operation in
constructors that can be called alot during intensive crypto
operations.
Now that you've done work on Delegate class - why not also keep
the (instanceof Cloneable) test ? That can serve as your fastpath
for the default JDK configuration AFAIK.
regards,
Sean.
On 05/06/2020 00:16, Weijun Wang wrote:
在 2020年6月5日，03:19，Valerie Peng <valerie.p...@oracle.com>
写道：
Can you give an example when these 2 rules have different
results? Is this only true for those implementation that
directly subclass MessageDigest?
Before this fix, even the Spi impl implements Cloneable the
instanceof check will always fail because the wrapper class,
i.e. MessageDigest.Delegate does not. However, if you call the
clone() (made public by the MessageDigest class), it will
succeed because Delegate.clone() checks to see if the spi object
implements the Cloneable interface, if yes, it will proceed to
call the spi clone(). So, for this scenario, the results are
different, e.g. instanceof returns false, but clone() succeeds.
This is just one example. Is this what you are asking?
No.
I understand this case, but this has already been fixed. Is there
any other example? Or are you only follow the words in the spec?
i.e. try clone() to see if it’s cloneable.
I am worried that try clone() is much heavier than just check
instanof Cloneable.
Thanks,
Max
