PureBasic

Convert a PuTTY Private Key (.ppk) to OpenSSH (.pem)

Demonstrates converting a PuTTY format private key to OpenSSH format. The .ppk is imported with FromPuttyPrivateKey and re-exported with ToOpenSshPrivateKey, both unencrypted and encrypted.

Note: The file paths are relative to the application's current working directory. Supply the paths to your own files.

Background: PuTTY and OpenSSH store the same underlying key material in different container formats, so converting between them is a re-encoding rather than a new key — the corresponding public key, and therefore the server-side authorized_keys entry, is unchanged. This matters when moving between Windows tooling built around PuTTY and Unix tooling that expects PEM. Note that the Password property serves double duty: it decrypts the key on import and encrypts it on export, so set it appropriately for each step.

Chilkat PureBasic Downloads

Download Chilkat for PureBasic

PureBasic

IncludeFile "CkSshKey.pb"

Procedure ChilkatExample()

    success.i = 0

    ;  Demonstrates converting a PuTTY format private key (.ppk) to OpenSSH (.pem) format.

    key.i = CkSshKey::ckCreate()
    If key.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ;  Set the password before importing an encrypted PuTTY key.  If the key is not encrypted it
    ;  makes no difference whether Password is set.  This should come from a secure source rather
    ;  than being hard-coded.
    CkSshKey::setCkPassword(key, "myKeyPassword")

    ;  LoadText is a convenience method that reads any text file into a string.  It does not itself
    ;  load the key.
    keyStr.s = CkSshKey::ckLoadText(key,"qa_data/putty_private_key.ppk")
    If CkSshKey::ckLastMethodSuccess(key) = 0
        Debug CkSshKey::ckLastErrorText(key)
        CkSshKey::ckDispose(key)
        ProcedureReturn
    EndIf

    success = CkSshKey::ckFromPuttyPrivateKey(key,keyStr)
    If success = 0
        Debug CkSshKey::ckLastErrorText(key)
        CkSshKey::ckDispose(key)
        ProcedureReturn
    EndIf

    ;  Export to an unencrypted OpenSSH key.
    bEncrypt.i = 0
    unencryptedKeyStr.s = CkSshKey::ckToOpenSshPrivateKey(key,bEncrypt)
    If CkSshKey::ckLastMethodSuccess(key) = 0
        Debug CkSshKey::ckLastErrorText(key)
        CkSshKey::ckDispose(key)
        ProcedureReturn
    EndIf

    success = CkSshKey::ckSaveText(key,unencryptedKeyStr,"qa_output/unencrypted_openssh.pem")
    If success = 0
        Debug CkSshKey::ckLastErrorText(key)
        CkSshKey::ckDispose(key)
        ProcedureReturn
    EndIf

    ;  Export to an encrypted OpenSSH key.  The Password property supplies the passphrase used to
    ;  encrypt the output.
    bEncrypt = 1
    CkSshKey::setCkPassword(key, "myExportPassword")
    encryptedKeyStr.s = CkSshKey::ckToOpenSshPrivateKey(key,bEncrypt)
    If CkSshKey::ckLastMethodSuccess(key) = 0
        Debug CkSshKey::ckLastErrorText(key)
        CkSshKey::ckDispose(key)
        ProcedureReturn
    EndIf

    success = CkSshKey::ckSaveText(key,encryptedKeyStr,"qa_output/encrypted_openssh.pem")
    If success = 0
        Debug CkSshKey::ckLastErrorText(key)
        CkSshKey::ckDispose(key)
        ProcedureReturn
    EndIf

    Debug "Done!"


    CkSshKey::ckDispose(key)


    ProcedureReturn
EndProcedure