DataFlex

Verfies an RSA Signature

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Verifies an RSA signature against the original data. DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Variant vBd
    Handle hoBd
    Integer i
    Variant vBdSig
    Handle hoBdSig
    Variant vPubKey
    Handle hoPubKey
    Handle hoRsa
    String sTemp1

    Move False To iSuccess

    // The following data was signed by the following example:
    // RSA Sign using a Private Key on a USB Token or Smartcard
    Get Create (RefClass(cComChilkatBinData)) To hoBd
    If (Not(IsComObjectCreated(hoBd))) Begin
        Send CreateComObject of hoBd
    End

    For i From 0 To 100
        Get ComAppendEncoded Of hoBd "000102030405060708090A0B0C0D0E0F" "hex" To iSuccess
    Loop

    // Load the signature
    Get Create (RefClass(cComChilkatBinData)) To hoBdSig
    If (Not(IsComObjectCreated(hoBdSig))) Begin
        Send CreateComObject of hoBdSig
    End
    Get ComLoadFile Of hoBdSig "rsaSignatures/test1.sig" To iSuccess
    If (iSuccess = False) Begin
        Showln "Failed to load the RSA signature"
        Procedure_Return
    End

    // Get the public key to be used for signature verification.
    Get Create (RefClass(cComChilkatPublicKey)) To hoPubKey
    If (Not(IsComObjectCreated(hoPubKey))) Begin
        Send CreateComObject of hoPubKey
    End
    Get ComLoadFromFile Of hoPubKey "rsaKeys/chilkat-rsa-2048.pem" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoPubKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatRsa)) To hoRsa
    If (Not(IsComObjectCreated(hoRsa))) Begin
        Send CreateComObject of hoRsa
    End
    Get pvComObject of hoPubKey to vPubKey
    Get ComUsePublicKey Of hoRsa vPubKey To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoRsa To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Verify the hash of the data against the signature.
    // We pass in the original data.  Internally, the hash is generated
    // and used to validate the signature.
    // Validating the RSA signature means two things:  
    // (1) the original data is exactly what was signed, and 
    // (2) it was signed by the owner of the RSA private key.
    Get pvComObject of hoBd to vBd
    Get pvComObject of hoBdSig to vBdSig
    Get ComVerifyBd Of hoRsa vBd "sha256" vBdSig To iSuccess

    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoRsa To sTemp1
        Showln sTemp1
        Showln "Signature invalid."
    End
    Else Begin
        Showln "Signature valid."
    End



End_Procedure