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Asked: 2015-10-25 05:05:52 +0800 CST

In OpenSSH DEBUG1 output on connecting, what does the number in the `Server accepts key` line refer to?

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When I connect to remote systems, specifically in this case using OpenSSH 6.0p1 Debian-4+deb7u2, if I use the -v switch to see what's going on one of the lines printed is:

debug1: Server accepts key: pkalg ssh-rsa blen 567

This looks to me like the server has accepted the identification public key (which is mentioned as offered on the immediately preceding line), which is great.

However, what does the 567 at the end refer to? "blen" sounds like it could be "bit length", but 567 isn't related to any bit length that I know of, even if converting bits to bytes.

Google was distinctly unhelpful, most likely because this stanza appears in more or less every ssh -v somewhere.example.com output that anyone has ever posted, but at least shows that the number varies (149, 277 and 279 are all on Google's first page of hits, when restricting to ssh-rsa exchanges).

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1 Answers

  1. The blen indicates the signature bytelength followed by it values.

    So in this case your public/private key was generated 4012 bit long thus you will have value of 567 of the signature.

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