Brian,
How would it work with a "new bucket"? I am just not connecting the issue of padding
and DHE signatures Andy is adding. Please expand a bit.
Dmitry
________________________________________
From: Brian Bockelman <[log in to unmask]>
Sent: Friday, December 7, 2018 3:09:37 PM
To: Dmitry O Litvintsev
Cc: [log in to unmask]
Subject: Re: question about using DH_compute_key calls in XrdCryptosslCipher
Hi Dmitry,
It's a timely email - about 1 hour ago, Andy merged a PR that was tinkering with the contents of this bucket (adding a signature to the DHE to mitigate a MiTM).
Unfortunately, OpenSSL 1.0.2h is fairly new compared to the minimum version Xrootd must support (RHEL6's 1.0.1e).
What if we introduce a new bucket type for this and the extension that Andy just merged? How accepting is the dCache code of new bucket types?
Brian
> On Dec 7, 2018, at 2:58 PM, Dmitry O Litvintsev <[log in to unmask]> wrote:
>
> Hi,
>
> dCache uses bouncycastle (BC) java crypto library.
> When we updated to BC version 1.5 we started to see occasional
> (about 1 in 200) exceptions:
>
> javax.crypto.BadPaddingException: pad block corrupted
>
> when using xrdcp with gsi security against dCache xrootd server.
> (secure handshake fails).
>
> We have tracked down the problem to the padding the secret with leading
> zeroes when converting number to to byte array that has been introduced
> in BC based on RFC 2631 (2.1.2) specification and the use of DH_compute_key in XrdCryptosslCipher in xrdcp client.
>
> We replaced DH_compute_key with DH_compute_key_padded calls and do not
> observe the issue anymore.
>
> DH_compute_key_padded appears in openssl in version 1.0.2h [25 Aug 2016]:
>
> """
> *) New function DH_compute_key_padded() to compute a DH key and pad with
> leading zeroes if needed: this complies with SP800-56A et al.
> [Steve Henson]
>
> """
>
> Are there principal objections/considerations of not using DH_compute_key_padded in XrdCryptosslCipher? (beyond compatibility issue - obviously a client implemented w/ DH_compute_key_padded would not work against server implemented w/ DH_compute_key).
>
> If turns out there are no objections we could think of some backward-compatible way
> of introducing these functions.
>
> Thank you,
> Dmitry
>
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