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From Sitaraman Vilayannur <vrsitaramanietfli...@gmail.com>
Subject Re: Key Rotation in Data-at-Rest Encryption
Date Sun, 14 Jun 2015 07:11:39 GMT
Hi Arun,
Thanks for your response.
Could you explain this a bit further for me....
Is the EZ key version same as an alias for the key?
The EDEK is stored in the extended attributes of the file and the EZkey
Version is stored
 in the FileInfo  why is the EZKey Version not stored in the extended
attributes too.
Where is the FileInfo object persisted? Is it in the NameNode?
How is the KeyMaterial derived from the KeyAlias and where is the mapping
between the two stored? Is it in the KMS?
Thanks much for your help in this.
Sitaraman

On Sun, Jun 14, 2015 at 12:14 PM, Arun Suresh <asuresh@cloudera.com> wrote:

> Hello Sitaraman,
>
> It is the EZ key "version" that is used to generate the EDEK (and which is
> ultimately stored in the encrypted file's extended attributes
> '*raw.hdfs.crypto.encryption.info
> <http://raw.hdfs.crypto.encryption.info>*'), not really the the EZ key
> itself (which is stored in the directory's extended attribute ‘
> *raw.hdfs.crypto.encryption.zone*’).
>
> Essentially, each file in a directory has a unique EDEK.. and an EDEK is is
> generated with the current version of the directory EZ key. The EDEK along
> with the EZ key version is stored in the FIleInfo. While decrypting, both
> these are passed on to the KMS which provides the client with the DEK which
> can be used to decrypt the file.
>
> Hope this clarifies things.
>
> Cheers
> -Arun
>
> On Sat, Jun 13, 2015 at 9:51 PM, Sitaraman Vilayannur <
> vrsitaramanietflists@gmail.com> wrote:
>
> > HDFSDataatRestEncryption.pdf says the following about key
> rotation..(please
> > see appended below at the end of the mail)
> > If the existing files do not have their EDEKs reencrypted using the new
> > ezkeyid, how would the existing files be decrypted? That is where is the
> > mapping between files and its EZKey (for after key rotation different
> files
> > have different EZKeys)ids stored and how is it retrieved?
> > Thanks
> > Sitaraman
> >
> > Key Rotation
> > When the administrator causes a key rotation of the EZkey
> > in the KMS, the encryption zone’s EZkey
> > (stored in the encryption zone directory’s
> raw.hdfs.crypto.encryption.zone
> > extended attribute) gets the new keyid and version (only the version
> > changes). Any new files
> > created in the encryption zone have their DEKs encrypted using the new
> key
> > version. Existing
> > files do not have their EDEKs reencrypted using the new ezkeyid/
> > version, but this will be considered as a future enhancement. Note that a
> > key rotation only needs to causes a reencryption of the DEK, not a
> > reencryption of the underlying file.
> >
>

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