Yubico Forum

Re: Problem with understanding HMAC-SHA1 challenge-response

2011-01-30T11:59:07+01:00

It works, thank you.
I also made the mistake to 'putbuffer' the NIST string in hex encoding.
One improvement of the test container could be, that it displays a warning if the user tries to 'putbuffer' something which is not valid according to the current data encoding.

Best regards,

Josef

Statistics: Posted by jschroettle — Sun Jan 30, 2011 11:59 am

Re: Problem with understanding HMAC-SHA1 challenge-response

2011-01-30T03:07:01+01:00

As there is only one buffer for both in- and out transaction, the input data must be written for each request. If sequential HMAC operations are performed, the input data is taken from the previous operation's out data and I guess that is why you experience this behavior.

In the sample client container, do the following steps:

1. Set data encoding to Ascii and click PutBuffer. The string "Sample #2" is written to the buffer

2. Set data encoding to hex (you can verify the data in hex by clicking GetBuffer, which then yields VT_BSTR 53616d706c65202332)

3. Check config #2

4. Press hmacSha1

5. The NIST string is displayed in the get field as VT_BSTR 0922d3405faa3d194f82a45830737d5cc6c75d24

The sample is maybe a bit unintuitive here so thanks for pointing this out. We shall update the manual.

Please let me know if this solved your problem.

Best regards,

JakobE
Hardware- and firmware guy @ Yubico

Statistics: Posted by Jakob — Sun Jan 30, 2011 3:07 am

Problem with understanding HMAC-SHA1 challenge-response

2011-01-29T22:05:14+01:00

Hi there,

I try to integrate HMAC-SHA1 challenge-response into one of my programs.
So I set my config #2 to HMAC-SHA1, variable size, NIST test key (3031..43)
My first experiments are with the 'Sample YubiClientAPI test container'.
When I set the PutBuffer to 'Sample #2' and press 'hmacSha1' I get a different result every time I press the button, but never the NIST vector (0922...) which I should get according to the document 'Yubikey Client COM API' Version 1.0.
What am I doing wrong?
Why is the result changing and not static?
Is the manual wrong or the software?
Thank you for your help

Josef

Statistics: Posted by jschroettle — Sat Jan 29, 2011 10:05 pm