(DataFlex) How to Generate an Elliptic Curve Shared Secret

Demonstrates how to generate an ECC (Elliptic Curve Cryptography) shared secret. Imagine a cilent has one ECC private key, the server has another. A shared secret is computed by each side providing it's public key to the other. The private keys are kept private.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Variant vPrngClient
    Handle hoPrngClient
    Handle hoEccClient
    Variant vPrivKeyClient
    Handle hoPrivKeyClient
    Variant vPubKeyClient
    Handle hoPubKeyClient
    Variant vPrngServer
    Handle hoPrngServer
    Handle hoEccServer
    Variant vPrivKeyServer
    Handle hoPrivKeyServer
    Variant vPubKeyServer
    Handle hoPubKeyServer
    Variant vPubKeyFromServer
    Handle hoPubKeyFromServer
    String sSharedSecret1
    Variant vPubKeyFromClient
    Handle hoPubKeyFromClient
    String sSharedSecret2
    String sTemp1
    Boolean bTemp1

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

    // This example includes both client-side and server-side code.
    // Each code segment is marked as client-side or server-side.
    // Imagine these segments are running on separate computers...

    // -----------------------------------------------------------------
    // (Client-Side) Generate an ECC key, save the public part to a file.
    // -----------------------------------------------------------------
    Get Create (RefClass(cComChilkatPrng)) To hoPrngClient
    If (Not(IsComObjectCreated(hoPrngClient))) Begin
        Send CreateComObject of hoPrngClient
    End
    Get Create (RefClass(cComChilkatEcc)) To hoEccClient
    If (Not(IsComObjectCreated(hoEccClient))) Begin
        Send CreateComObject of hoEccClient
    End
    Get pvComObject of hoPrngClient to vPrngClient
    Get ComGenEccKey Of hoEccClient "secp256r1" vPrngClient To vPrivKeyClient
    If (IsComObject(vPrivKeyClient)) Begin
        Get Create (RefClass(cComChilkatPrivateKey)) To hoPrivKeyClient
        Set pvComObject Of hoPrivKeyClient To vPrivKeyClient
    End
    Get ComLastMethodSuccess Of hoEccClient To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoEccClient To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComGetPublicKey Of hoPrivKeyClient To vPubKeyClient
    If (IsComObject(vPubKeyClient)) Begin
        Get Create (RefClass(cComChilkatPublicKey)) To hoPubKeyClient
        Set pvComObject Of hoPubKeyClient To vPubKeyClient
    End
    Get ComSavePemFile Of hoPubKeyClient False "qa_output/eccClientPub.pem" To iSuccess
    Send Destroy of hoPubKeyClient

    // -----------------------------------------------------------------
    // (Server-Side) Generate an ECC key, save the public part to a file.
    // -----------------------------------------------------------------
    Get Create (RefClass(cComChilkatPrng)) To hoPrngServer
    If (Not(IsComObjectCreated(hoPrngServer))) Begin
        Send CreateComObject of hoPrngServer
    End
    Get Create (RefClass(cComChilkatEcc)) To hoEccServer
    If (Not(IsComObjectCreated(hoEccServer))) Begin
        Send CreateComObject of hoEccServer
    End
    Get pvComObject of hoPrngServer to vPrngServer
    Get ComGenEccKey Of hoEccServer "secp256r1" vPrngServer To vPrivKeyServer
    If (IsComObject(vPrivKeyServer)) Begin
        Get Create (RefClass(cComChilkatPrivateKey)) To hoPrivKeyServer
        Set pvComObject Of hoPrivKeyServer To vPrivKeyServer
    End
    Get ComLastMethodSuccess Of hoEccServer To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoEccServer To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComGetPublicKey Of hoPrivKeyServer To vPubKeyServer
    If (IsComObject(vPubKeyServer)) Begin
        Get Create (RefClass(cComChilkatPublicKey)) To hoPubKeyServer
        Set pvComObject Of hoPubKeyServer To vPubKeyServer
    End
    Get ComSavePemFile Of hoPubKeyServer False "qa_output/eccServerPub.pem" To iSuccess
    Send Destroy of hoPubKeyServer

    // -----------------------------------------------------------------
    // (Client-Side) Generate the shared secret using our private key, and the other's public key.
    // -----------------------------------------------------------------

    // Imagine that the server sent the public key PEM to the client.
    // (This is simulated by loading the server's public key from the file.
    Get Create (RefClass(cComChilkatPublicKey)) To hoPubKeyFromServer
    If (Not(IsComObjectCreated(hoPubKeyFromServer))) Begin
        Send CreateComObject of hoPubKeyFromServer
    End
    Get ComLoadFromFile Of hoPubKeyFromServer "qa_output/eccServerPub.pem" To iSuccess
    Get pvComObject of hoPubKeyFromServer to vPubKeyFromServer
    Get ComSharedSecretENC Of hoEccClient vPrivKeyClient vPubKeyFromServer "base64" To sSharedSecret1
    Send Destroy of hoPrivKeyClient

    // -----------------------------------------------------------------
    // (Server-Side) Generate the shared secret using our private key, and the other's public key.
    // -----------------------------------------------------------------

    // Imagine that the client sent the public key PEM to the server.
    // (This is simulated by loading the client's public key from the file.
    Get Create (RefClass(cComChilkatPublicKey)) To hoPubKeyFromClient
    If (Not(IsComObjectCreated(hoPubKeyFromClient))) Begin
        Send CreateComObject of hoPubKeyFromClient
    End
    Get ComLoadFromFile Of hoPubKeyFromClient "qa_output/eccClientPub.pem" To iSuccess
    Get pvComObject of hoPubKeyFromClient to vPubKeyFromClient
    Get ComSharedSecretENC Of hoEccServer vPrivKeyServer vPubKeyFromClient "base64" To sSharedSecret2
    Send Destroy of hoPrivKeyServer

    // ---------------------------------------------------------
    // Examine the shared secrets.  They should be the same.
    // Both sides now have a secret that only they know.
    // ---------------------------------------------------------
    Showln sSharedSecret1
    Showln sSharedSecret2


End_Procedure