key load public invalid format

Question

I used PuTTY Key Generator to generate a 4096 bit RSA-2 key with a passphrase   I save the  ppk and an openSSL format public key  The putty format public key doesn t work   In any case  my error is as follows     ssh -T git github com key load public  invalid format Enter passphrase for key   c Users Dan  ssh id rsa   Hi Dan  You ve successfully authenticated  but GitHub does not provide shell access    What s the issue   I use Pageant to load the keys and i use Git Bash to try the ssh connection  I ve also loaded the key into GitHub  not sure what i m doing wrong   I ve tried adding a new line and not adding a new line in GitHub

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TL DR  also ensure that your id rsa pub is in ascii   UTF-8  I had the same problem  however the accepted answer alone did not work because of the text encoding  which was an additional  easy-to-miss issue  When I run ssh-keygen -f    ssh id rsa -y  gt     ssh id rsa pub  in Windows PowerShell  it saves the output to id rsa pub in UTF-16 LE BOM encoding  not in UTF-8  This is a property of some installations of PowerShell  which was discussed in Using PowerShell to write a file in UTF-8 without the BOM  Apparently  OpenSSH does not recognise the former text encoding and produces an identical error  key load public  invalid format  Copying and pasting the output of ssh-keygen -f    ssh id rsa -y into a text editor is the simplest way to solve this  P S  This could be an addition to the accepted answer  but I don t have enough karma to comment here yet

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There is a simple solution if you can install and use puttygen tool  Below are the steps  You should have the passphrase of the private key   step 1  Download latest puttygen and open puttygen  step 2  Load your existing private key file  see below image    step 3  Enter passphrase for key if asked and hit ok    step 4  as shown in the below image select  conversion  menu tab and select  Export OpenSSH key     Save new private key file at preferred location and use accordingly

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If you re using Windows 10 with the built-in SSH  as of August 2020 it only supports ed25519 keys  You ll get the key load public  invalid format error if you use e g  an RSA key  As per this GitHub issue it should be fixed via Windows Update some time in 2020  So one solution is to just wait for the update to ship  If you can t wait  a workaround is to generate a new ed25519 key  which is good advice anyway   gt  ssh-keygen -o -a 100 -t ed25519  You can use it with e g  github  but some older systems might not support this newer format  After generating your key  if you re using either of the below features  don t forget to update them      ssh config might still point to the old key  Add the new key to ssh-agent via the ssh-add command

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As Roland mentioned in their answer  it s a warning that the ssh-agent doesn t understand the format of the public key and even then  the public key will not be used locally   However  I can also elaborate and answer why the warning is there  It simply boils down to the fact that the PuTTY Key Generator generates two different public key formats depending on what you do in the program   Note  Throughout my explanation  the key files I will be using generating will be named id rsa with their appropriate extensions  Furthermore  for copy-paste convenience  the parent folder of the keys will be assumed to be    ssh   Adjust these details to suit your needs as desired   The Formats  Link to the relevant PuTTY documentation  SSH-2  When you save a key using the PuTTY Key Generator using the  Save public key  button  it will be saved in the format defined by RFC 4716   Example   ---- BEGIN SSH2 PUBLIC KEY ---- Comment   github-example-key  AAAAB3NzaC1yc2EAAAABJQAAAQEAhl CNy9wI1GVdiHAJQV0CkHnMEqW7 Si9WYF i2fSBrsGcmqeb5EwgnhmTcPgtM5ptGBjUZR84nxjZ8SPmnLDiDyHDPIsmwLBHxcp pY0fhRSGtWL5fT8DGm9EfXaO1QN8c31VU IkD8niWA6NmHNE1qEqpph3DznVzIm3 oMrongEjGw7sDP48ZTZp2saYVAKEEuGC1YYcQ1g20yESzo7aP70ZeHmQqI9nTyEA ip3mL20 qHNsHfW8hJAchaUN8CwNQABJaOozYijiIUgdbtSTMRDYPi7fjhgB3bA9 tBjh7cOyuU c4M4D6o2mAVYdLAWMBkSoLG8Oel6TCcfpO nElw   ---- END SSH2 PUBLIC KEY ----   OpenSSH  Contrary to popular belief  this format doesn t get saved by the generator  However it is generated and shown in the text box titled  Public key for pasting into OpenSSH authorized keys file   To save it as a file  you have to manually copy it from the text box and paste it into a new text file   For the key shown above  this would be   ssh-rsa AAAAB3NzaC1yc2EAAAABJQAAAQEAhl CNy9wI1GVdiHAJQV0CkHnMEqW7 Si9WYFi2fSBrsGcmqeb5EwgnhmTcPgtM5ptGBjUZR84nxjZ8SPmnLDiDyHDPIsmwLBHxcppY0fhRSGtWL5fT8DGm9EfXaO1QN8c31VU IkD8niWA6NmHNE1qEqpph3DznVzIm3oMrongEjGw7sDP48ZTZp2saYVAKEEuGC1YYcQ1g20yESzo7aP70ZeHmQqI9nTyEAip3mL20 qHNsHfW8hJAchaUN8CwNQABJaOozYijiIUgdbtSTMRDYPi7fjhgB3bA9tBjh7cOyuU c4M4D6o2mAVYdLAWMBkSoLG8Oel6TCcfpO nElw   github-example-key   The format of the key is simply ssh-rsa  lt signature gt   lt comment gt  and can be created by rearranging the SSH-2 formatted file   Regenerating Public Keys  If you are making use of ssh-agent  you will likely also have access to ssh-keygen   If you have your OpenSSH Private Key  id rsa file   you can generate the OpenSSH Public Key File using   ssh-keygen -f    ssh id rsa -y  gt     ssh id rsa pub   If you only have the PUTTY Private Key  id rsa ppk file   you will need to convert it first    Open the PuTTY Key Generator On the menu bar  click  File     Load private key  Select your id rsa ppk file On the menu bar  click  Conversions     Export OpenSSH key  Save the file as id rsa  without an extension    Now that you have an OpenSSH Private Key  you can use the ssh-keygen tool as above to perform manipulations on the key   Bonus  The PKCS 1 PEM-encoded Public Key Format  To be honest  I don t know what this key is used for as I haven t needed it  But I have it in my notes I ve collated over the years and I ll include it here for wholesome goodness  The file will look like this   -----BEGIN RSA PUBLIC KEY----- MIIBCAKCAQEAhl CNy9wI1GVdiHAJQV0CkHnMEqW7 Si9WYFi2fSBrsGcmqeb5Ew gnhmTcPgtM5ptGBjUZR84nxjZ8SPmnLDiDyHDPIsmwLBHxcppY0fhRSGtWL5fT8D Gm9EfXaO1QN8c31VU IkD8niWA6NmHNE1qEqpph3DznVzIm3oMrongEjGw7sDP48 ZTZp2saYVAKEEuGC1YYcQ1g20yESzo7aP70ZeHmQqI9nTyEAip3mL20 qHNsHfW8 hJAchaUN8CwNQABJaOozYijiIUgdbtSTMRDYPi7fjhgB3bA9tBjh7cOyuU c4M4D 6o2mAVYdLAWMBkSoLG8Oel6TCcfpO nElwIBJQ   -----END RSA PUBLIC KEY-----   This file can be generated using an OpenSSH Private Key  as generated in  Regenerating Public Keys  above  using   ssh-keygen -f    ssh id rsa -y -e -m pem  gt     ssh id rsa pem   Alternatively  you can use an OpenSSH Public Key using   ssh-keygen -f    ssh id rsa pub -e -m pem  gt     ssh id rsa pem   References     key load public  invalid format     on AskUbuntu The Secure Shell  SSH  Public Key File Format Converting OpenSSH public keys

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Instead of directly saving the private key Go to Conversions and Export SSh Key  Had the same issue and this worked for me

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So  after update I had the same issue  I was using PEM key file without extension and simply adding  pem fixed my issue  Now the file is key file pem

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The error is misleading - it says  quot pubkey quot  while pointing to a private key file    ssh id rsa  In my case  it was simply a missing public key  as I haven t restored it  from a vault    DETAILS I used to skip deploying    ssh id rsa pub by automated scripts  All ssh usages worked  but the error made me think of a possible mess  Not at all - strace helped to notice that the trigger was actually the   pub file  strace ssh example com     openat AT FDCWD   quot  home uvsmtid  ssh id rsa pub quot   O RDONLY    -1 ENOENT  No such file or directory      write 2   quot load pubkey   quot  home uvsmtid  ssh  quot      57    57 load pubkey  quot  home uvsmtid  ssh id rsa quot   invalid format

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I had the same warning  It was a very old key  I regenerated a key on the current OpenSSH 7  and the error was gone

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In the case you copy your public key with clipboard and paste it  it may happen the public key string can be broken which contains new-line   Make sure your public key string formed as one line

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It seems that ssh cannot read your public key  But that doesn t matter   You upload your public key to github  but you authenticate using your private key  See e g  the FILES section in ssh 1

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uvsmtid Your post finally lead me into the right direction  simply deleting  actually renaming  the public key file id rsa pub solved the problem for me  that git was working though nagging about invalid format  Not quite sure  yet the file is not actually needed  since the pub key can be extracted from private key file id rsa anyway

[git] key_load_public: invalid format

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