x/crypto/ssh: Add FingerprintLegacyMD5 and FingerprintSHA256 methods

Implement a standards-compliant fingerprint format method (RFC 4716 section 4)
and a newer SHA256 fingerprint format method.

Fixes golang/go#12292

Change-Id: I4f3f8fc1d0a263cb3b0964d0078e69006a39d1a5
Reviewed-on: https://go-review.googlesource.com/32814
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2 files changed