(DataFlex) Verify an RSA Signature Against the Signed String

See more Apple Keychain Examples

Demonstrates how to validate an RSA Signature against the string that was signed.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoSb
    Boolean iCrlfLineEnding
    Integer i
    Boolean iSuccess
    String sBase64_rsa_sig
    Variant vPubKey
    Handle hoPubKey
    Boolean iSuccess
    Handle hoRsa
    String sSignedString
    String sTemp1

    // Create the same string we previously signed in this example: 
    // RSA Sign utf-8 Bytes of String to get Base64 RSA Signature

    Get Create (RefClass(cComChilkatStringBuilder)) To hoSb
    If (Not(IsComObjectCreated(hoSb))) Begin
        Send CreateComObject of hoSb
    End
    Move True To iCrlfLineEnding

    For i From 0 To 10
        Get ComAppendLine Of hoSb "This is a test." iCrlfLineEnding To iSuccess
    Loop

    Move "gWgpEXQqvXN6wh0MuFXPiw2xCb8cnmdizBT1TD1Tpm2GlJ8gnD59DGSj35GGXk1tM+mCOvMa2uW/9gmz8p6A90JLbn918i/2wKGvcde4wXnzPO7JADSNn2UwYzf3rp4/q/JrHv1GZETRJhABSFqTxOgdmdbEJQE/zijOSctCtQAM2CTb6t2BO8uHKSSUAwPH2cbeWxqsaVRLT4ruk5nZOxhoLgLMSjupiSzbE8zSTkkFOEHD+Mbb2xwg85AI0E4DsUnp+hLwwtS0blesgSyvtBY8oJODJeFcJsR7JDOTPdzHQHgJRl/2A4ij5xT91TpXy7ok43jhT6O9j7Q3qrafIQ==" To sBase64_rsa_sig

    // 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 ComImportPublicKeyObj Of hoRsa vPubKey To iSuccess

    // Verify the string against the signature.
    // We signed the utf-8 byte representation of the string, so we must indicate
    // to also validate against the utf-8 byte representation.
    Set ComCharset Of hoRsa To "utf-8"
    Set ComEncodingMode Of hoRsa To "base64"
    Get ComGetAsString Of hoSb To sSignedString
    Get ComVerifyStringENC Of hoRsa sSignedString "sha256" sBase64_rsa_sig 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