(DataFlex) RSA Signature/Verify with .key and .cer

See more RSA Examples

Demonstrates how to use a .key file (private key) and digital certificate (.cer, public key) to create and verify an RSA signature.

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

Chilkat ActiveX Downloads

ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Variant vPrivKey
    Handle hoPrivKey
    Handle hoRsa
    String sStrData
    String sHexSig
    Handle hoCert
    Variant vPubKey
    Handle hoPubKey
2    Handle hoRsa2
    String sTemp1

    Move False To iSuccess

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

    Get Create (RefClass(cComChilkatPrivateKey)) To hoPrivKey
    If (Not(IsComObjectCreated(hoPrivKey))) Begin
        Send CreateComObject of hoPrivKey
    End

    // Load the private key from an RSA .key file:
    Get ComLoadPemFile Of hoPrivKey "privateKey.key" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoPrivKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatRsa)) To hoRsa
    If (Not(IsComObjectCreated(hoRsa))) Begin
        Send CreateComObject of hoRsa
    End

    // Import the private key into the RSA component:
    Get pvComObject of hoPrivKey to vPrivKey
    Get ComUsePrivateKey Of hoRsa vPrivKey To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoRsa To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Create the signature as a hex string:
    Set ComEncodingMode Of hoRsa To "hex"

    Move "This is the string to be signed." To sStrData

    // Sign the string using the sha256 hash algorithm.
    // Other valid choices are "md2", "sha1", "sha384",
    // "sha512", and "md5".
    Get ComSignStringENC Of hoRsa sStrData "sha256" To sHexSig

    Showln sHexSig

    // Load a digital certificate from a .cer file:
    Get Create (RefClass(cComChilkatCert)) To hoCert
    If (Not(IsComObjectCreated(hoCert))) Begin
        Send CreateComObject of hoCert
    End

    Get ComLoadFromFile Of hoCert "myCert.cer" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCert To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatPublicKey)) To hoPubKey
    If (Not(IsComObjectCreated(hoPubKey))) Begin
        Send CreateComObject of hoPubKey
    End
    Get pvComObject of hoPubKey to vPubKey
    Get ComGetPublicKey Of hoCert vPubKey To iSuccess

    // Now verify using a new instance of the RSA object:
    Get Create (RefClass(cComChilkatRsa)) To hoRsa2
    If (Not(IsComObjectCreated(hoRsa2))) Begin
        Send CreateComObject of hoRsa2
    End

    // Import the public key into the RSA object:
    Get pvComObject of hoPubKey to vPubKey
    Get ComUsePublicKey Of hoRsa2 vPubKey To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoRsa2 To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // The signature is a hex string, so make sure the EncodingMode is correct:
    Set ComEncodingMode Of hoRsa2 To "hex"

    // Verify the signature:
    Get ComVerifyStringENC Of hoRsa2 sStrData "sha256" sHexSig To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoRsa2 To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Success."


End_Procedure