Tcl

Save a Private Key as an Encrypted PKCS #8 DER File

Demonstrates the Chilkat PrivateKey.SavePkcs8EncryptedFile method, which saves the key as password-protected PKCS #8 DER. The first argument is the password and the second is the destination path. The cipher is selected by Pkcs8EncryptAlg.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: This is the recommended way to persist a key to disk: the binary .der is encrypted under a passphrase, so a stolen file is useless without it. Reach for it whenever a key is stored or shipped. Choose the encryption cipher with Pkcs8EncryptAlg and source the password securely.

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Tcl


load ./chilkat.dll

set success 0

#  Load a private key to export.
set privKey [new_CkPrivateKey]

set success [CkPrivateKey_LoadPemFile $privKey "qa_data/private.pem"]
if {$success == 0} then {
    puts [CkPrivateKey_lastErrorText $privKey]
    delete_CkPrivateKey $privKey
    exit
}

#  The key password is not hard-coded in a real application; obtain it from an interactive
#  prompt, environment variable, or a secrets vault.
set password "myKeyPassword"

#  Save as password-protected PKCS #8 DER.  The 1st argument is the password and the 2nd is the
#  destination path.  The cipher is selected by the Pkcs8EncryptAlg property.
set success [CkPrivateKey_SavePkcs8EncryptedFile $privKey $password "qa_output/private_pkcs8_enc.der"]
if {$success == 0} then {
    puts [CkPrivateKey_lastErrorText $privKey]
    delete_CkPrivateKey $privKey
    exit
}

puts "Saved (encrypted)."

delete_CkPrivateKey $privKey