DataFlex

ECDSA Sign and Verify Data using Different Hash Algorithms

See more ECC Examples

Demonstrates how to create ECDSA signatures on data using different hash algorithms.

Note: This example requires Chilkat v9.5.0.85 or greater because the SignBd and VerifyBd methods were added in v9.5.0.85.

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Variant vPrivKey
    Handle hoPrivKey
    Variant vBd
    Handle hoBd
    Handle hoEcdsa
    Variant vPrng
    Handle hoPrng
    String sSig
    Variant vPubKey
    Handle hoPubKey
    Handle hoEcc2
    Integer iResult
    String sTemp1

    Move False To iSuccess

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

    // First load an ECDSA private key to be used for signing.
    Get Create (RefClass(cComChilkatPrivateKey)) To hoPrivKey
    If (Not(IsComObjectCreated(hoPrivKey))) Begin
        Send CreateComObject of hoPrivKey
    End
    Get ComLoadEncryptedPemFile Of hoPrivKey "qa_data/ecc/secp256r1-key-pkcs8-secret.pem" "secret" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoPrivKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Load some data to be signed.
    Get Create (RefClass(cComChilkatBinData)) To hoBd
    If (Not(IsComObjectCreated(hoBd))) Begin
        Send CreateComObject of hoBd
    End
    Get ComLoadFile Of hoBd "qa_data/hamlet.xml" To iSuccess
    If (iSuccess = False) Begin
        Showln "Failed to load file to be hashed."
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatEcc)) To hoEcdsa
    If (Not(IsComObjectCreated(hoEcdsa))) Begin
        Send CreateComObject of hoEcdsa
    End
    Get Create (RefClass(cComChilkatPrng)) To hoPrng
    If (Not(IsComObjectCreated(hoPrng))) Begin
        Send CreateComObject of hoPrng
    End

    // Sign the sha256 hash of the data.  Return the ECDSA signature in the base64 encoding.
    Showln "ECDSA signing the sha256 hash of the data..."
    Get pvComObject of hoBd to vBd
    Get pvComObject of hoPrivKey to vPrivKey
    Get pvComObject of hoPrng to vPrng
    Get ComSignBd Of hoEcdsa vBd "sha256" "base64" vPrivKey vPrng To sSig
    Showln "sig = " sSig

    // Verify the signature against the original data.
    // (We must use the same hash algorithm that was used when signing.)

    // Load the public key that corresponds to the private key used for signing.
    Get Create (RefClass(cComChilkatPublicKey)) To hoPubKey
    If (Not(IsComObjectCreated(hoPubKey))) Begin
        Send CreateComObject of hoPubKey
    End
    Get ComLoadFromFile Of hoPubKey "qa_data/ecc/secp256r1-pub.pem" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoPubKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatEcc)) To hoEcc2
    If (Not(IsComObjectCreated(hoEcc2))) Begin
        Send CreateComObject of hoEcc2
    End
    Get pvComObject of hoBd to vBd
    Get pvComObject of hoPubKey to vPubKey
    Get ComVerifyBd Of hoEcc2 vBd "sha256" sSig "base64" vPubKey To iResult
    If (iResult <> 1) Begin
        Get ComLastErrorText Of hoEcc2 To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Verified!"

    // ----------------------------------------------------------------------------------------
    // Let's do the same thing, but with sha384 hashing...

    Showln "--------------------------------------------"
    Showln "ECDSA signing the sha384 hash of the data..."

    Get pvComObject of hoBd to vBd
    Get pvComObject of hoPrivKey to vPrivKey
    Get pvComObject of hoPrng to vPrng
    Get ComSignBd Of hoEcdsa vBd "sha384" "base64" vPrivKey vPrng To sSig
    Showln "sig = " sSig

    Get pvComObject of hoBd to vBd
    Get pvComObject of hoPubKey to vPubKey
    Get ComVerifyBd Of hoEcc2 vBd "sha384" sSig "base64" vPubKey To iResult
    If (iResult <> 1) Begin
        Get ComLastErrorText Of hoEcc2 To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Verified!"


End_Procedure