Forum OpenACS Development: Re: ns_hmac and byte array

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2: Re: ns_hmac and byte array (response to 1)
Posted by Gustaf Neumann on 01/23/19 08:56 PM

Hi Dave,

actually, the code seems to make the right things. With a little debugging in naviserver activated, one can see that the binary string is correctly handled as a bytearray:

% set b [binary format H* "abcd1234"]
«Í4
%  set h [ns_hmac string -digest SHA512 $b "This is a test"]
hmac key (len 4): ab cd 12 34 
7d783715c6aedd1e9d0ee5f310da502a0540048a525d64964a9bb7e7b8c6782cacbfba8a2870cd7c9892a99da89404ca47f219dcb50c7ae5fb454704734473b8

Per default, the ouput encoding is hex, but one can specify as well base64url, base64, or binary. What result did you expect?

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3: Re: ns_hmac and byte array (response to 2)
Posted by Dave Bauer on 01/24/19 12:40 AM
Thanks Gustaf, your example returns the same result as my Python example.

When I run this code on my Naviserver it returns a different result.
I am not sure if this is a result of a different library I have or some Naviserver encoding setting perhaps. Very curious.

set b [binary format H* "abcd1234"]
set h [ns_hmac string -digest SHA512 $b "This is a test"]

b results in the same value «Í4
but h contains a different result
ffc30b14fc4589bcb3fea23a8cd7825adc64cb5072462985d62f93d005b2fc89454614616f3f08a64fa63800217eb963d2bdc6284ff801edc1cd607e9473fa75

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4: Re: ns_hmac and byte array (response to 2)
Posted by Dave Bauer on 01/24/19 12:47 AM
Gustaf, can you explain which code generates the "hmac key (len 4): ab cd 12 34" message? Thanks!
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5: Re: ns_hmac and byte array (response to 4)
Posted by Gustaf Neumann on 01/24/19 09:53 AM
activate the line [1] in the source code, activate the function hexPrint (same file), recompile, reinstall, run the naviserver shell e.g. with "/usr/local/ns/bin/nsd -c" and type in the ns_hmac commands.

Do you see a different result, or do get the same result, but expecting a different one?

[1] https://bitbucket.org/naviserver/naviserver/src/227b2724a06eeab64a03c1e56d6d270a57e4d855/nsd/tclcrypto.c#lines-870

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6: Re: ns_hmac and byte array (response to 5)
Posted by Dave Bauer on 01/24/19 02:47 PM
Gustaf,

I believe the result your code returns is the correct response.

My code is returning a different value, but it looks like its the same. I'll try adding the debugging code.
I checked and I am running Naviserver 4.99.16.

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7: Re: ns_hmac and byte array (response to 6)
Posted by Gustaf Neumann on 01/24/19 08:39 PM
Dave, please test with 4.99.17 if possible (there were changes in the meantime, for both [1] and the crypto support in [2]. Upgrade could help. If not it might be a problem with the Tcl version.

[1] https://openacs.org/forums/message-view?message_id=5380070
[2] https://openacs.org/webpush-demo/webpush-demo.tcl

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8: Re: ns_hmac and byte array (response to 7)
Posted by Dave Bauer on 01/25/19 01:41 AM
Gustaf, thank you!

I compiled Naviserver 4.99.17 with Tcl 8.5.19 to see if the issue resolved itself, and I am not getting the same result as your example.

It does appear the Naviserver version affected the results, and not the Tcl version.

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9: Re: ns_hmac and byte array (response to 8)
Posted by Gustaf Neumann on 01/25/19 09:15 AM
Glad that this helped! Tcl bytearrays are more tricky than it looks at the first sight.

all the best
-g