DataFlex

CMS Sign Hash

Demonstrates how to use the SignHashENC method to sign a pre-computed hash. This method creates a CMS signature (PKCS7 detached signature).

This example requires Chilkat v9.5.0.90 or later.

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoCrypt
    String sBase64Hash
    Variant vCert
    Handle hoCert
    String sBase64CmsSig
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

    // This example requires 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

    // Create the hash to be signed...
    Set ComHashAlgorithm Of hoCrypt To "sha256"
    Set ComEncodingMode Of hoCrypt To "base64"
    Set ComCharset Of hoCrypt To "utf-8"
    // Create the SHA256 hash of a string using the utf-8 byte representation.
    // Return the hash as base64.
    Get ComHashStringENC Of hoCrypt "This is the string to be hashed" To sBase64Hash

    // Load a certificate for signing.
    Get Create (RefClass(cComChilkatCert)) To hoCert
    If (Not(IsComObjectCreated(hoCert))) Begin
        Send CreateComObject of hoCert
    End
    Get ComLoadPfxFile Of hoCert "qa_data/pfx/cert_test123.pfx" "test123" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCert To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get pvComObject of hoCert to vCert
    Get ComSetSigningCert Of hoCrypt vCert To iSuccess

    // Sign the hash to create a base64 CMS signature (which does not contain the original data).
    // We can get the signature in a single line of base64 by specifying "base64", or 
    // we can get multi-line base64 by specifying "base64_mime".
    Set ComEncodingMode Of hoCrypt To "base64_mime"
    Get ComSignHashENC Of hoCrypt sBase64Hash "sha256" "base64" To sBase64CmsSig
    Get ComLastMethodSuccess Of hoCrypt To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoCrypt To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Note: In the above call to SignHashENC, the encoding of the returned CMS signature is specified by the EncodingMode property.
    // However, the encoding of the passed-in hash is indicated by the 3rd argument.

    Showln "CMS Signature: " sBase64CmsSig


End_Procedure