DataFlex

Create and Verify an Opaque PKCS7/CMS Signature

See more Digital Signatures Examples

Demonstrates how 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
    Variant vPrivKey
    Handle hoPrivKey
    String sPassword
    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 PFX/.p12, Java keystore, JWK, Windows registry-based certificate stores, and other sources.
    // This example will load the certificate from a .crt and the private key from a .key file

    Get Create (RefClass(cComChilkatCert)) To hoCert
    If (Not(IsComObjectCreated(hoCert))) Begin
        Send CreateComObject of hoCert
    End
    // The LoadFromFile method will automatically detect the format and load it.
    Get ComLoadFromFile Of hoCert "qa_data/certs/test_12345678a.cer" To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoCert To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Our private key is in an encrypted PKCS8 format.
    // If you don't know the format of your key, but you do know it's encrypted,
    // and requires a password, then just call any of the Chilkat methods that load
    // a private key w/ a password argument.  Chilkat will auto-detect the format
    // and load it correctly even if it's not the format indicated by the method name..
    Get Create (RefClass(cComChilkatPrivateKey)) To hoPrivKey
    If (Not(IsComObjectCreated(hoPrivKey))) Begin
        Send CreateComObject of hoPrivKey
    End
    Move "12345678a" To sPassword
    Get ComLoadPkcs8EncryptedFile Of hoPrivKey "qa_data/certs/test_12345678a.key" sPassword To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoPrivKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Set properties required for signing.

    // Tell it to use the cert and private key we've loaded.
    Get pvComObject of hoCert to vCert
    Get pvComObject of hoPrivKey to vPrivKey
    Get ComSetSigningCert2 Of hoCrypt vCert vPrivKey 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

    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