(SQL Server) 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

// Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
//
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @privKey int
    EXEC @hr = sp_OACreate 'Chilkat_9_5_0.PrivateKey', @privKey OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @password nvarchar(4000)
    SELECT @password = '12345678a'
    DECLARE @success int
    EXEC sp_OAMethod @privKey, 'LoadPkcs8EncryptedFile', @success OUT, 'qa_data/certs/test_12345678a.key', @password
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @privKey, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @privKey
        RETURN
      END

    DECLARE @xml int
    EXEC @hr = sp_OACreate 'Chilkat_9_5_0.Xml', @xml OUT

    EXEC sp_OAMethod @privKey, 'GetXml', @sTmp0 OUT
    EXEC sp_OAMethod @xml, 'LoadXml', @success OUT, @sTmp0

    -- The XML contains the parts of the key in base64.

    PRINT 'Private Key XML:'
    EXEC sp_OAMethod @xml, 'GetXml', @sTmp0 OUT
    PRINT @sTmp0

    -- We can get the base64 modulus like this:
    DECLARE @modulus nvarchar(4000)
    EXEC sp_OAMethod @xml, 'GetChildContent', @modulus OUT, 'Modulus'

    PRINT 'base64 modulus = ' + @modulus

    -- To convert to hex:
    DECLARE @binDat int
    EXEC @hr = sp_OACreate 'Chilkat_9_5_0.BinData', @binDat OUT

    EXEC sp_OAMethod @binDat, 'AppendEncoded', @success OUT, @modulus, 'base64'
    DECLARE @hexModulus nvarchar(4000)
    EXEC sp_OAMethod @binDat, 'GetEncoded', @hexModulus OUT, 'hex'

    PRINT 'hex modulus = ' + @hexModulus

    -- Now get the modulus from the cert:
    DECLARE @cert int
    EXEC @hr = sp_OACreate 'Chilkat_9_5_0.Cert', @cert OUT

    EXEC sp_OAMethod @cert, 'LoadFromFile', @success OUT, 'qa_data/certs/test_12345678a.cer'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @cert, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @privKey
        EXEC @hr = sp_OADestroy @xml
        EXEC @hr = sp_OADestroy @binDat
        EXEC @hr = sp_OADestroy @cert
        RETURN
      END

    -- The cert contains the public key, which is composed of the
    -- modulus + exponent (for RSA keys).
    DECLARE @pubKey int
    EXEC sp_OAMethod @cert, 'ExportPublicKey', @pubKey OUT

    EXEC sp_OAMethod @pubKey, 'GetXml', @sTmp0 OUT
    EXEC sp_OAMethod @xml, 'LoadXml', @success OUT, @sTmp0

    PRINT 'Public Key XML:'
    EXEC sp_OAMethod @xml, 'GetXml', @sTmp0 OUT
    PRINT @sTmp0

    -- Proceed in the same way as before....
    EXEC sp_OAMethod @xml, 'GetChildContent', @modulus OUT, 'Modulus'

    PRINT 'base64 modulus = ' + @modulus

    -- To convert to hex:
    EXEC sp_OAMethod @binDat, 'Clear', @success OUT
    EXEC sp_OAMethod @binDat, 'AppendEncoded', @success OUT, @modulus, 'base64'
    EXEC sp_OAMethod @binDat, 'GetEncoded', @hexModulus OUT, 'hex'

    PRINT 'hex modulus = ' + @hexModulus

    EXEC @hr = sp_OADestroy @pubKey


    EXEC @hr = sp_OADestroy @privKey
    EXEC @hr = sp_OADestroy @xml
    EXEC @hr = sp_OADestroy @binDat
    EXEC @hr = sp_OADestroy @cert


END
GO