How do I get an SSH2 public key working for an OpenSSH server/target?

Download cygwin for ssh-keygen! Then:
ssh-keygen -i -f myExistingSSH2_public_key_file.pub > myNewOpenssh_public_key_file.pub

cygwin: bash here, prompt here, zsh here

I always forget how I can extend the Windows directory context menu with cygwin shell entries:

Install:
$ chere -i -s cmd
$ chere -i -s zsh
$ chere -i -s bash

Uninstall:
$ chere -u -s cmd
$ chere -u -s zsh
$ chere -u -s bash

Notes for using GPG to encrypt and decrypt backup files

Notes for using GPG:

„To create a new public/private key pair, run:
gpg –gen-key and follow the prompts.

To list public keys, run:
gpg –list-keys

To list private or secret keys, run:
gpg –list-secret-keys

To export a public key to an ascii text file, run:
gpg -a –export NAME > yourpublickey.gpg

To export a private (or secret) key to an ascii text file, run:
gpg -a –export-secret-keys NAME > yourprivatekey.gpg

To delete a public key from the local key ring:
gpg –delete-keys NAME

To delete a secret key from the local key ring:
gpg –delete-secret-key NAME

To encrypt a file, use:
gpg -r NAME –output OUTFILE.gpg –encrypt INFILE

To decrypt a file, use:
gpg -r NAME –output OUTFILE –decrypt INFILE.gpg

If you leave out the ‘-r’ option, it will prompt you for the name of the user whose key should be used.“

gpg (GnuPG): howto change algorithm, compression and hashing preferences

uid 1
uid 2
…
setpref s10 s9 s8 s7 s4 s3 s2 z3 z2 z1 z0 h2 h8 h3
updpref
save