(PureBasic) Working with PEM Encrypted Private Keys

Demonstrates how to load and save PEM encrypted private keys.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkPrivateKey.pb"
IncludeFile "CkFileAccess.pb"
IncludeFile "CkPem.pb"

Procedure ChilkatExample()

    success.i = 0

    ; This example assumes the Chilkat API to have been previously unlocked.
    ; See Global Unlock Sample for sample code.

    success = 0

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

    pemPassword.s = "secret"

    ; To load a PEM file containing encrypted private keys, simply
    ; provide the password.
    success = CkPem::ckLoadPemFile(pem,"/Users/chilkat/testData/pem/pemContainingEncryptedPrivateKeys.pem",pemPassword)
    If success = 0
        Debug CkPem::ckLastErrorText(pem)
        CkPem::ckDispose(pem)
        ProcedureReturn
    EndIf

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

    pemText.s = CkFileAccess::ckReadEntireTextFile(fac,"/Users/chilkat/testData/pem/pemContainingEncryptedPrivateKeys.pem",pemPassword)

    ; To load a PEM from a string, call LoadPem instead of LoadPemFile:
    success = CkPem::ckLoadPem(pem,pemText)
    If success = 0
        Debug CkPem::ckLastErrorText(pem)
        CkPem::ckDispose(pem)
        CkFileAccess::ckDispose(fac)
        ProcedureReturn
    EndIf

    ; A few notes:
    ; The PEM may contain both private keys and certificates (or anything else).
    ; The password is utilized for whatever content in the PEM is encrypted.  
    ; It is OK to have both encrypted and non-encrypted content within a given PEM.

    ; PEM private keys can be encrypted in different formats.  The LoadPem and LoadPemFile
    ; methods automatically handle the different formats.
    ; One format is PKCS8 and is indicated by this delimiter within the PEM:

    ; -----BEGIN ENCRYPTED PRIVATE KEY-----
    ; MIICoTAbBgkqhkiG9w0BBQMwDgQIfdD0zv24lgkCAggABIICgE0PdHJmRbNs6cBX
    ; ...

    ; Another format, we'll call "passphrase" looks like this in the PEM:
    ; -----BEGIN RSA PRIVATE KEY-----
    ; Proc-Type: 4,ENCRYPTED
    ; DEK-Info: DES-EDE3-CBC,A4215544D11C5D0C
    ; 
    ; paqy9XRexcSjurHfG0xhCaUD0HrvIdhuC0CbRxxxeMlkLaV6+uT80rBxt2AaibWG
    ; ...

    ; Show the bit length of each private key:
    i.i
    numPrivateKeys.i = CkPem::ckNumPrivateKeys(pem)
    If numPrivateKeys = 0
        Debug ("Error: Expected the PEM to contain private keys.")
        CkPem::ckDispose(pem)
        CkFileAccess::ckDispose(fac)
        ProcedureReturn
    EndIf

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

    For i = 1 To numPrivateKeys
        CkPem::ckPrivateKeyAt(pem,i - 1,privKey)
        Debug Str(i) + ": " + Str(CkPrivateKey::ckBitLength(privKey)) + " bits"
    Next


    CkPem::ckDispose(pem)
    CkFileAccess::ckDispose(fac)
    CkPrivateKey::ckDispose(privKey)


    ProcedureReturn
EndProcedure