SQL Server

About RSA Public/Private Keys

See more RSA Examples

This example provides some additional information for understanding public/private key pairs. In demonstrates how a private key is a superset of the public key. A public key contains the modulus and exponent. The matching private key also contains the modulus and exponent, but also contains the additional private key parts. SQL Server

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    DECLARE @cert int
    EXEC @hr = sp_OACreate 'Chilkat.Cert', @cert OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- Load a digital certificate.
    EXEC sp_OAMethod @cert, 'LoadFromFile', @success OUT, 'digitalCert.cer'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @cert, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @cert
        RETURN
      END

    -- A .cer file does not contain the private key.  It should contain
    -- the public key...
    DECLARE @pubKey int
    EXEC @hr = sp_OACreate 'Chilkat.PublicKey', @pubKey OUT

    EXEC sp_OAMethod @cert, 'GetPublicKey', @success OUT, @pubKey

    -- Let's have a look at it (in XML format).

    PRINT 'Public Key from Certificate:'
    EXEC sp_OAMethod @pubKey, 'GetXml', @sTmp0 OUT
    PRINT @sTmp0

    -- An RSA public key consists of a modulus and exponent.

    -- An RSA private key includes both the modulus and exponent,
    -- as well as other "big" numbers: P, Q, D, etc.

    -- Let's load an RSA private key from a DER-encoded file:
    DECLARE @privKey int
    EXEC @hr = sp_OACreate 'Chilkat.PrivateKey', @privKey OUT

    EXEC sp_OAMethod @privKey, 'LoadAnyFormatFile', @success OUT, 'PrivateKey.key', ''
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @privKey, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @cert
        EXEC @hr = sp_OADestroy @pubKey
        EXEC @hr = sp_OADestroy @privKey
        RETURN
      END

    -- If this private key is the matching half to the public key from
    -- the certificate, then the modulus and exponent should
    -- be identical.  (Thus, a "private key" really contains both the public part as well as the private parts...).

    PRINT 'Private Key from DER:'
    EXEC sp_OAMethod @privKey, 'GetXml', @sTmp0 OUT
    PRINT @sTmp0

    EXEC @hr = sp_OADestroy @cert
    EXEC @hr = sp_OADestroy @pubKey
    EXEC @hr = sp_OADestroy @privKey


END
GO