(SQL Server) Verfies an RSA Signature

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Verifies an RSA signature against the original data.

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
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    -- The following data was signed by the following example:
    -- RSA Sign using a Private Key on a USB Token or Smartcard
    DECLARE @bd int
    -- Use "Chilkat_9_5_0.BinData" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.BinData', @bd OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @i int

    SELECT @i = 0
    WHILE @i <= 100
      BEGIN
        DECLARE @success int
        EXEC sp_OAMethod @bd, 'AppendEncoded', @success OUT, '000102030405060708090A0B0C0D0E0F', 'hex'
        SELECT @i = @i + 1
      END

    -- Load the signature
    DECLARE @bdSig int
    -- Use "Chilkat_9_5_0.BinData" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.BinData', @bdSig OUT

    DECLARE @success int
    EXEC sp_OAMethod @bdSig, 'LoadFile', @success OUT, 'rsaSignatures/test1.sig'
    IF @success = 0
      BEGIN

        PRINT 'Failed to load the RSA signature'
        EXEC @hr = sp_OADestroy @bd
        EXEC @hr = sp_OADestroy @bdSig
        RETURN
      END

    -- Get the public key to be used for signature verification.
    DECLARE @pubKey int
    -- Use "Chilkat_9_5_0.PublicKey" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.PublicKey', @pubKey OUT

    EXEC sp_OAMethod @pubKey, 'LoadFromFile', @success OUT, 'rsaKeys/chilkat-rsa-2048.pem'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @pubKey, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @bd
        EXEC @hr = sp_OADestroy @bdSig
        EXEC @hr = sp_OADestroy @pubKey
        RETURN
      END

    DECLARE @rsa int
    -- Use "Chilkat_9_5_0.Rsa" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Rsa', @rsa OUT

    EXEC sp_OAMethod @rsa, 'ImportPublicKeyObj', @success OUT, @pubKey

    -- 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.
    EXEC sp_OAMethod @rsa, 'VerifyBd', @success OUT, @bd, 'sha256', @bdSig

    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @rsa, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0

        PRINT 'Signature invalid.'
      END
    ELSE
      BEGIN

        PRINT 'Signature valid.'
      END

    EXEC @hr = sp_OADestroy @bd
    EXEC @hr = sp_OADestroy @bdSig
    EXEC @hr = sp_OADestroy @pubKey
    EXEC @hr = sp_OADestroy @rsa


END
GO