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

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
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
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
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
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
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
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
Glad that this helped! Tcl bytearrays are more tricky than it looks at the first sight.

all the best
-g