DataFlex

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.

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Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoKey
    String sKeyStr
    Boolean iBEncrypt
    String sUnencryptedKeyStr
    String sEncryptedKeyStr
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

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

    Get Create (RefClass(cComChilkatSshKey)) To hoKey
    If (Not(IsComObjectCreated(hoKey))) Begin
        Send CreateComObject of hoKey
    End

    //  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.
    Set ComPassword Of hoKey To "myKeyPassword"

    //  LoadText is a convenience method that reads any text file into a string.  It does not itself
    //  load the key.
    Get ComLoadText Of hoKey "qa_data/putty_private_key.ppk" To sKeyStr
    Get ComLastMethodSuccess Of hoKey To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComFromPuttyPrivateKey Of hoKey sKeyStr To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Export to an unencrypted OpenSSH key.
    Move False To iBEncrypt
    Get ComToOpenSshPrivateKey Of hoKey iBEncrypt To sUnencryptedKeyStr
    Get ComLastMethodSuccess Of hoKey To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComSaveText Of hoKey sUnencryptedKeyStr "qa_output/unencrypted_openssh.pem" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Export to an encrypted OpenSSH key.  The Password property supplies the passphrase used to
    //  encrypt the output.
    Move True To iBEncrypt
    Set ComPassword Of hoKey To "myExportPassword"
    Get ComToOpenSshPrivateKey Of hoKey iBEncrypt To sEncryptedKeyStr
    Get ComLastMethodSuccess Of hoKey To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComSaveText Of hoKey sEncryptedKeyStr "qa_output/encrypted_openssh.pem" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Done!"


End_Procedure