(SQL Server) Duplicate openssl rsautl -encrypt –in mytext.txt -out mytest.enc -inkey mycertificate.cer -certin –pkcs

Demonstrates how to duplicate this OpenSSL command:

openssl.exe  rsautl -encrypt –in mytext.txt -out mytest.enc -inkey mycertificate.cer -certin –pkcs

Important: The RSA encryption algorithm produces different results for each call, even when encrypting the same data with the same key. Decryption however, will produce the correct results. This example demonstrates.

The reason this occurs is that RSA encryption uses PKCS1 v1.5 padding, and this padding scheme uses random bytes. It is random bytes in the padding that causes the result to be different each time.

The mytext.txt file is a small file. (RSA can only be used to encrypt or sign small amounts of data.)

How much data can be encrypted 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 @cert int
    -- Use "Chilkat_9_5_0.Cert" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Cert', @cert OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- Load the certificate from a file.
    DECLARE @success int
    EXEC sp_OAMethod @cert, 'LoadFromFile', @success OUT, 'mycertificate.cer'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @cert, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @cert
        RETURN
      END

    -- Load the file to be encrypted.
    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, 'mytext.txt'

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

    -- Get the cert's public key.
    DECLARE @pubkey int
    EXEC sp_OAMethod @cert, 'ExportPublicKey', @pubkey OUT

    -- Import the public key into the RSA component:
    EXEC sp_OAMethod @rsa, 'ImportPublicKeyObj', @success OUT, @pubkey
    IF @success <> 1
      BEGIN
        EXEC @hr = sp_OADestroy @pubkey

        EXEC sp_OAGetProperty @rsa, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @cert
        EXEC @hr = sp_OADestroy @bd
        EXEC @hr = sp_OADestroy @rsa
        RETURN
      END

    EXEC @hr = sp_OADestroy @pubkey

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

    -- Encrypt the contents of bd, replacing it with the encrypted data.
    DECLARE @bUsePrivateKey int
    SELECT @bUsePrivateKey = 0
    EXEC sp_OAMethod @rsa, 'EncryptBd', @success OUT, @bd, @bUsePrivateKey
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @rsa, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @cert
        EXEC @hr = sp_OADestroy @bd
        EXEC @hr = sp_OADestroy @rsa
        RETURN
      END

    -- Save the RSA encrypted data to a file.
    EXEC sp_OAMethod @bd, 'WriteFile', @success OUT, 'mytest.enc'
    IF @success <> 1
      BEGIN

        PRINT 'Failed to write RSA encrypted output file.'
        EXEC @hr = sp_OADestroy @cert
        EXEC @hr = sp_OADestroy @bd
        EXEC @hr = sp_OADestroy @rsa
        RETURN
      END


    PRINT 'Success.'

    EXEC @hr = sp_OADestroy @cert
    EXEC @hr = sp_OADestroy @bd
    EXEC @hr = sp_OADestroy @rsa


END
GO