Problems calculating signature

[Granqvist, Hans]

> I'd be great if somebody volunteered to write down the 
> complete set of steps to do the OpenID crypto, and annotated 
> it with an actual numeric example for each step.

Agree, that would be great.

> Our experience at NetMesh implementing OpenID for InfoGrid 
> was similar to Thom's -- it took at lot longer than expected 
> until we got it working, but then only 9 out of 10 times. It 
> took a few months of cursing (and lots of help) before we 
> realized that there was a leading-zero problem in one of the 
> steps that would only occur rarely depending on the mood of 
> the random generator.

Johannes, if you managed to do it correctly, you'd be able 
to straw-man that set of steps, no?  ;)

> A numerically-annotated set of steps would be really helpful.  
> Actually, several annotations to catch things like leading 
> zeros, negative numbers etc. etc. would be even more so.

These problems seem to echo the issue with two-complement leading 
zero bytes -- to make sure the two's-complement form always is 
positive. I'm curious: was your implementation using Java 
BigIntegers?)

Perhaps the RFC 2437 (PKCS#1) I2OSP() function can shed some 
light and provide an alternate starting point to the 
openid btwoc() function?

Thanks,
Hans