(DataFlex) Get RSA Key Modulus from .cer or .key

Demonstrates how to get the RSA key modulus from either the certificate (.cer) or RSA key (.key). OpenSSL commands to do the same would be:

openssl x509 -inform DER -in "test.cer"  -modulus -noout 

openssl pkcs8 -inform DER -in​ "test.key"​ -outform PEM -passin pass:"12345​678a​"
   | openssl rsa -inform PEM -modulus -noout 

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

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoPrivKey
    String sPassword
    Boolean iSuccess
    Handle hoXml
    String sModulus
    Handle hoBinDat
    String sHexModulus
    Handle hoCert
    Variant vPubKey
    Handle hoPubKey
    String sTemp1

    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

    Get Create (RefClass(cComChilkatXml)) To hoXml
    If (Not(IsComObjectCreated(hoXml))) Begin
        Send CreateComObject of hoXml
    End
    Get ComGetXml Of hoPrivKey To sTemp1
    Get ComLoadXml Of hoXml sTemp1 To iSuccess

    // The XML contains the parts of the key in base64.
    Showln "Private Key XML:"
    Get ComGetXml Of hoXml To sTemp1
    Showln sTemp1

    // We can get the base64 modulus like this:
    Get ComGetChildContent Of hoXml "Modulus" To sModulus
    Showln "base64 modulus = " sModulus

    // To convert to hex:
    Get Create (RefClass(cComChilkatBinData)) To hoBinDat
    If (Not(IsComObjectCreated(hoBinDat))) Begin
        Send CreateComObject of hoBinDat
    End
    Get ComAppendEncoded Of hoBinDat sModulus "base64" To iSuccess
    Get ComGetEncoded Of hoBinDat "hex" To sHexModulus
    Showln "hex modulus = " sHexModulus

    // Now get the modulus from the cert:
    Get Create (RefClass(cComChilkatCert)) To hoCert
    If (Not(IsComObjectCreated(hoCert))) Begin
        Send CreateComObject of hoCert
    End

    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

    // The cert contains the public key, which is composed of the
    // modulus + exponent (for RSA keys).
    Get ComExportPublicKey Of hoCert To vPubKey
    If (IsComObject(vPubKey)) Begin
        Get Create (RefClass(cComChilkatPublicKey)) To hoPubKey
        Set pvComObject Of hoPubKey To vPubKey
    End

    Get ComGetXml Of hoPubKey To sTemp1
    Get ComLoadXml Of hoXml sTemp1 To iSuccess
    Showln "Public Key XML:"
    Get ComGetXml Of hoXml To sTemp1
    Showln sTemp1

    // Proceed in the same way as before....
    Get ComGetChildContent Of hoXml "Modulus" To sModulus
    Showln "base64 modulus = " sModulus

    // To convert to hex:
    Get ComClear Of hoBinDat To iSuccess
    Get ComAppendEncoded Of hoBinDat sModulus "base64" To iSuccess
    Get ComGetEncoded Of hoBinDat "hex" To sHexModulus
    Showln "hex modulus = " sHexModulus

    Send Destroy of hoPubKey


End_Procedure