(SQL Server) Duplicate openssl rsautl -sign -in small.dat -inkey private.pem -out rsautl.sig

Demonstrates how to duplicate this OpenSSL command:

openssl rsautl -sign -in small.dat -inkey private.pem -out rsautl.sig

How much data can be signed with "openssl rsautl"? The maximum size (in bytes) is the key size minus the overhead for the padding. The overhead size depends on the padding. With OAEP padding, the overhead is 42 bytes. With the default PKCSv1.5 padding, the overhead is 11 bytes.

Given a 2048-bit RSA key (256 bytes) and using PKCSv1.5 padding, the max data size that can be signed is 256 - 11 = 245 bytes.

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)
    -- This example requires the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    DECLARE @pkey int
    -- Use "Chilkat_9_5_0.PrivateKey" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.PrivateKey', @pkey OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- Load the private key from an PEM file:
    DECLARE @success int
    EXEC sp_OAMethod @pkey, 'LoadPemFile', @success OUT, 'private.pem'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @pkey, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @pkey
        RETURN
      END

    -- Load the file to be signed.
    DECLARE @bd int
    -- Use "Chilkat_9_5_0.BinData" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.BinData', @bd OUT

    EXEC sp_OAMethod @bd, 'LoadFile', @success OUT, 'small.dat'

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

    -- Import the private key into the RSA component:
    EXEC sp_OAMethod @rsa, 'ImportPrivateKeyObj', @success OUT, @pkey
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @rsa, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @pkey
        EXEC @hr = sp_OADestroy @bd
        EXEC @hr = sp_OADestroy @rsa
        RETURN
      END

    -- OpenSSL uses big-endian.
    EXEC sp_OASetProperty @rsa, 'LittleEndian', 0

    -- Sign bd.  If successful, bd will contain the RSA signature that contains the original data.
    EXEC sp_OAMethod @rsa, 'OpenSslSignBd', @success OUT, @bd
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @rsa, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @pkey
        EXEC @hr = sp_OADestroy @bd
        EXEC @hr = sp_OADestroy @rsa
        RETURN
      END

    -- Save the binary signature to a file.
    EXEC sp_OAMethod @bd, 'WriteFile', @success OUT, 'rsautl.sig'
    IF @success <> 1
      BEGIN

        PRINT 'Failed to save output signature file.'
        EXEC @hr = sp_OADestroy @pkey
        EXEC @hr = sp_OADestroy @bd
        EXEC @hr = sp_OADestroy @rsa
        RETURN
      END


    PRINT 'Success.'

    EXEC @hr = sp_OADestroy @pkey
    EXEC @hr = sp_OADestroy @bd
    EXEC @hr = sp_OADestroy @rsa


END
GO