How to convert .ppk key to OpenSSH key under Linux?

Question

I know that is possible to convert .ppk under puttygen in Windows, but how to do that on Linux? Is this possible ?

Solution 1

Do it with Putty.

• Linux: with your package manager, install PuTTY (or the more minimal PuTTY-tools):

  • Ubuntu sudo apt-get install putty-tools
  • Debian-like apt-get install putty-tools
  • RPM based yum install putty
  • Gentoo emerge putty
  • Archlinux sudo pacman -S putty
  • etc.

• OS X: Install Homebrew, then run brew install putty

Place your keys in some directory, e.g. your home folder. Now convert the PPK keys to SSH keypairs:cache search

To generate the private key:

cd ~
puttygen id_dsa.ppk -O private-openssh -o id_dsa

and to generate the public key:

puttygen id_dsa.ppk -O public-openssh -o id_dsa.pub

Move these keys to ~/.ssh and make sure the permissions are set to private for your private key:

mkdir -p ~/.ssh
mv -i ~/id_dsa* ~/.ssh
chmod 600 ~/.ssh/id_dsa
chmod 666 ~/.ssh/id_dsa.pub

If you have already tried to perform a 'git clone' operation you might need to do this also

chmod 666 ~/.ssh/known_hosts

Solution 2

ssh-keygen -i -f id_dsa_1024_a.pub > id_dsa_1024_a_openssh.pub

• -i flag is import from other than openssh format
• -f flag means read from input file

Source: a blogpost at burnz.wordpress.com

Solution 3

Get the private key:

open the .ppk file in puttygen:

puttygen ~/.ssh/id_dsa.ppk

export as openssh:

Conversions → Export OpenSSH key

Get the public key:

open like before the private key with puttygen, the public key is under public key for pasting into OpenSSH authorized_keys file

Solution 4

I prepared a Docker container to make life simpler:

docker run --rm \
           --volume=/path/to/file.ppk:/tmp/id_dsa.ppk \
           --volume=/path/to/output:/tmp/out/ \
           czerasz/putty-tools

Where:

• /path/to/file.ppk - local path to your ppk file
• /path/to/output - local path to where the private and public key should be placed

View more solutions

Comments

[oscarah]

.ppk files are the full key pairs, I don't think the command above or the blog post apply to that.

[jous]

I think I meant that it works if you use puttygen's "Save public key" button. ssh-keygen do not understand true .ppk files because they lack those '---- BEGIN SSH2 PUBLIC KEY ----' markers. You can find the public key in the .ppk file between lines "Public-Lines:.." and "Private-Lines:.." though.

[Amit Bera]

hi i already have a .pub then it is need to create public key again

[Ryan Shillington]

If you came here looking for how to do it in windows, run "puttygen yourkey.ppk", and then under the Conversions menu choose "Export OpenSSH key" to get the private key.

[Jasen]

This worked for me with a public-key file - puttygen seems to require a private key. it's seems that all it did was rearrange the base-64 part into a single line

[Tobi]

the solution from @jous is much nicer since you don't need the private key to convert a public key + you don't need to install putty

[vladkras]

I had to add this key to my ./ssh/config file Host mysite.com Hostname mysite.com IdentityFile ~/.ssh/id_dsa IdentitiesOnly yes

[Gert van den Berg]

This does not seem to cover private keys, which is why I would want to do the conversion, I already have a public key saved somewhere...

[Daniel W.]

Some elliptic curve formats (ECDS etc) are only available in the beta putty tools yet.

[pHiL]

great. thx for the image! however meanwhile its --volume=/path/to/file.ppk:/tmp/id.ppk and not id_dsa.ppk

[Alex]

Yeah, the ppk files I've seen have had the appropriate markers, and this has worked just fine.

[Geverson Carvalho]

You may like to add --network none

[Danon]

I get puttygen: error loading '/tmp/id.ppk': PuTTY key format too new