Re: [Exist-open] md5 hash sum of base64 binary

[Dan M. <dan...@gm...>]

Claudius has figured out that his EXPath crypto:hash() function does
in fact do the correct hash on the binary of the base64binary (not the
string version of the base64binary) to match the value that we get
from a file system or from the HEAD of S3 for a binary file.

So by just changing over to use his hash function we can now correctly
verify the md5 checksums of a file on disk.  Everyone should note that
the util:hash() and the crypto:hash() work the same for string but not
the same on base64Binary types.  I think this might be considered a
bug and I will add it to the bug tracker if other people agree.

Thanks Claudius!

By the way you can get the latest 0.2.2 version of the EXPATH crypto
module here:

http://code.google.com/p/existdb-contrib/downloads/list

And then just use the "Upload" on the package installer.

On the trunk you will need to change the conf.xml from:

 <module uri="http://kuberam.ro/ns/x-crypt"
class="ro.kuberam.xcrypt.XcryptModule" />

to be

<module uri="http://expath.org/ns/crypto"
class="org.expath.exist.crypto.ExistExpathCryptoModule" />

Note that we could not get the module to work when the jar file was in
the new package location here

/webapp/WEB-INF/expathrepo/expath-crypto-0.2.2/expath-crypto

So Claudius suggested that we manually copy the jar file into
lib/extensions and that worked.

Thanks! - Dan


On Sat, Nov 3, 2012 at 9:19 AM, Dan McCreary <dan...@gm...> wrote:
> I think the thing that Nick is trying to do is calculate the hash of
> the binary file on disk, not the base64Binary of the binary file.
>
> Here is a test I ran to show what we can do.
>
> xquery version "1.0";
>
> (: this is the value we get when we do the following:
>    on the mac
>    $ echo -n 'Hello World!' | md5
>
>    on windows with cygwin
>    $ echo -n 'Hello World!' | md5sum
> ed076287532e86365e841e92bfc50d8c *-
>
> $ md5sum red-square.png
> 28ec5059f163077a7734212d899a2175 *red-square.png
>
> Here we must take a binary file and get the base64 of it without any spaces
> $ base64 -w0 red-square.png | md5sum
> a339d67a458e9e7c707a7251e9a95bec *-
>
>  :)
> let $expected-value-hash-string := 'ed076287532e86365e841e92bfc50d8c'
>
> let $hash-hello-world := util:hash('Hello World!', 'md5', false())
>
> let $md5-string-test :=
>    if ($hash-hello-world = $expected-value-hash-string)
>       then 'pass'
>       else 'fail'
>
> (: test on a small binary png file in /tmp
>
> $ md5sum red-square.png
> 28ec5059f163077a7734212d899a2175 *red-square.png
>
> Here we must take a binary file and get the base64 of it without any spaces
> $ base64 -w0 red-square.png | md5sum
> a339d67a458e9e7c707a7251e9a95bec *-
>
> :)
> let $image-as-base-64 := util:binary-doc('/tmp/red-square.png')
>
> let $hash-red-square :=  util:hash($image-as-base-64, 'md5', false())
>
> let $hash-of-base64Binary-of-image := 'a339d67a458e9e7c707a7251e9a95bec'
>
> let $md5-base64-of-binary-test :=
>    if ( $hash-red-square =$hash-of-base64Binary-of-image)
>       then 'pass'
>       else 'fail'
>
> return
> <testcase name="md5-hash-on-binaries" classname="md5-binary">
>   <hash-hello-world>{$hash-hello-world}</hash-hello-world>
>   <string-pass-fail-code>{$md5-string-test}</string-pass-fail-code>
>
>   <hash-png>{$hash-red-square}</hash-png>
>   <binary-pass-fail-code>{$md5-base64-of-binary-test}</binary-pass-fail-code>
> </testcase>
>
>
> which returns:
>
> <testcase name="md5-hash-on-binaries" classname="md5-binary">
> <hash-hello-world>ed076287532e86365e841e92bfc50d8c</hash-hello-world>
> <string-pass-fail-code>pass</string-pass-fail-code>
> <hash-png>a339d67a458e9e7c707a7251e9a95bec</hash-png>
> <binary-pass-fail-code>pass</binary-pass-fail-code>
> </testcase>
>
> But is there a way to get the hash of a true binary within XQuery?
>
> - Dan
>
> On Sat, Nov 3, 2012 at 8:45 AM, nsincaglia <nsi...@nu...> wrote:
>> I am using Release 2.0.
>>
>>
>>
>> --
>> View this message in context: http://exist.2174344.n4.nabble.com/md5-hash-sum-of-base64-binary-tp4657005p4657007.html
>> Sent from the exist-open mailing list archive at Nabble.com.
>>
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>
>
>
> --
> Dan McCreary
> NoSQL Evangelist
> office: (952) 931-9198
> cell: (612) 986-1552



-- 
Dan McCreary
NoSQL Evangelist
office: (952) 931-9198
cell: (612) 986-1552