[ietf-dkim] Question regarding computing message hashes

[Roman Meisl]

Hello,

I've got a question regarding the computing of message hashes. In
chapter 3.7 is listed a formal notation for that algorithm:

       body-hash = hash-alg(canon_body)
       header-hash = hash-alg(canon_header || DKIM-SIG)
       signature = sig-alg(header-hash, key)

I'm not quite sure, what "||" means. I assume it means concatenation
of the two strings. Is that right?

Then it would perhaps be better to write
       header-hash = hash-alg(canon_header + DKIM-SIG)
or
       header-hash = hash-alg(concat(canon_header,DKIM-SIG))
in the second line or at least to mention concatenation explicitly in the
text.

TIA,
   Roman

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