DataFlex

A3/A4 Certificate to Create and Verify an Opaque PKCS7/CMS Signature

See more Digital Signatures Examples

Demonstrates how to use an A3 or A4 certificate w/ private key on a smartcard or token to create a PKCS7 opaque signature, and also how to verify an opaque signature.

An opaque signature is different than a detached PKCS7 signature in that it contains the original data. Verifying an opaque signature retrieves the original content.

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoCrypt
    Variant vCert
    Handle hoCert
    String sOriginalData
    String sOpaqueSig
    Handle hoVCrypt
    String sExtractedData
    String sTemp1
    Boolean bTemp1

    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(cComChilkatCrypt2)) To hoCrypt
    If (Not(IsComObjectCreated(hoCrypt))) Begin
        Send CreateComObject of hoCrypt
    End

    // A certificate and private key is needed to create a signature.
    // Chilkat provides many different ways to load a certificate and private key, such
    // as from a smartcards and hardware tokens, PFX/.p12, Java keystore, JWK, Windows registry-based certificate stores, and other sources.
    // This example will load the default certificate from the smartcard that is currently in
    // the smartcard reader.

    Get Create (RefClass(cComChilkatCert)) To hoCert
    If (Not(IsComObjectCreated(hoCert))) Begin
        Send CreateComObject of hoCert
    End

    // If the smartcard or token requires a PIN, we can set it here to avoid the dialog...
    Set ComSmartCardPin Of hoCert To "000000"

    Get ComLoadFromSmartcard Of hoCert "" To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoCert To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Tell it to use the cert and private key we've loaded.
    Get pvComObject of hoCert to vCert
    Get ComSetSigningCert Of hoCrypt vCert To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoCrypt To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Indicate we want the opaque signature in base64 format:
    Set ComEncodingMode Of hoCrypt To "base64"

    // Sign the string using the "utf-8" byte representation:
    Set ComCharset Of hoCrypt To "utf-8"

    // Create the opaque signature:
    Move "This is the string to be signed." To sOriginalData
    Get ComOpaqueSignStringENC Of hoCrypt sOriginalData To sOpaqueSig
    Get ComLastMethodSuccess Of hoCrypt To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoCrypt To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln sOpaqueSig

    // The output looks like this:
    // MIIPgQYJKoZIhvcNAQcCoIIPcjCCD24CAQExCzAJBgUrDgMCGgUAMC8GCSqGSIb3DQEHAaAiBCBUaGlzIGlzIHRoZSBzdHJpbmcgdG8gYmUgc...

    // ----------------------------------------------------------------------------------------------
    // Now let's verify the signature and retrieve the original data.
    // We'll use a new Crypt2 object to keep things completely separate...

    Get Create (RefClass(cComChilkatCrypt2)) To hoVCrypt
    If (Not(IsComObjectCreated(hoVCrypt))) Begin
        Send CreateComObject of hoVCrypt
    End

    // We only need the certificate to verify a signature (and extract the data from
    // an opaque signature).  The public key is always embedded within a certificate.
    Get pvComObject of hoCert to vCert
    Get ComSetVerifyCert Of hoVCrypt vCert To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoVCrypt To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Set ComEncodingMode Of hoVCrypt To "base64"
    Set ComCharset Of hoVCrypt To "utf-8"

    Get ComOpaqueVerifyStringENC Of hoVCrypt sOpaqueSig To sExtractedData
    Get ComLastMethodSuccess Of hoVCrypt To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoVCrypt To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "The extracted data: " sExtractedData

    // The output is:
    // The extracted data: This is the string to be signed.


End_Procedure