I have both TortoiseHg 2.3 64 bit and TortoiseGit 1.7.7 64 bit installed on Vista 64 bit.
Both TortoiseHg (ssh = "C:\Program Files\TortoiseHg\TortoisePlink.exe" -ssh -2 -C -batch entry in mercurial.ini) and TortoiseGit (GIT_SSH environment variable set to C:\Program Files\TortoiseGit\bin\TortoisePlink.exe) are configured to use PuTTy's plink (command-line interface to the PuTTY back ends) versions distributed with them.
I have Pageant (PuTTy authentification client) running and proper ssh key loaded. However any hg or git command results in error dialog titled PuTTY Fatal Error being displayed with the message:
Disconnected: No supported authentication methods available. (server sent:publickey)
At the same time using original plink.exe provided with PuTTy works.
Why doesn't TortoisePlink work?
Best Answer
There is a problem with 64-bit TortoiseSVN working with 32-bit pageant. Either use 32-bit TortoiseSVN (IMO there is no real need for it to be 64-bit). Unofficially, the devs only supply 32-bit binaries. A 64-bit build of PuTTY is available here.
It seems that the TortoiseSVN devs put the blame on PuTTY...