SQL Server

Compress and Encrypt a Large File (Low and Constant Memory Footprint)

See more Compression Examples

Demonstrates how to compress and encrypt a large file such that the memory footprint remains low and constant.

Note: This example requires Chilkat v9.5.0.99 or greater.

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

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

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

    EXEC sp_OASetProperty @compress, 'Algorithm', 'deflate'

    -- Set encryption params.
    -- The possible values are the same as for the corresponding properties in the Chilkat Crypt2 class/object.
    -- The encoded IV and Key must be specified as hex.
    DECLARE @json int
    EXEC @hr = sp_OACreate 'Chilkat.JsonObject', @json OUT

    EXEC sp_OAMethod @json, 'UpdateString', @success OUT, 'cryptAlgorithm', 'aes'
    EXEC sp_OAMethod @json, 'UpdateString', @success OUT, 'cipherMode', 'cbc'
    EXEC sp_OAMethod @json, 'UpdateInt', @success OUT, 'keyLength', 128
    EXEC sp_OAMethod @json, 'UpdateInt', @success OUT, 'paddingScheme', 0
    EXEC sp_OAMethod @json, 'UpdateString', @success OUT, 'encodedIV', '000102030405060708090A0B0C0D0E0F'
    EXEC sp_OAMethod @json, 'UpdateString', @success OUT, 'encodedKey', '000102030405060708090A0B0C0D0E0F'

    -- Do file-to-file compression+encryption in a single call.
    DECLARE @inPath nvarchar(4000)
    SELECT @inPath = 'qa_data/largeFile.dat'
    DECLARE @outPath nvarchar(4000)
    SELECT @outPath = 'c:/temp/qa_output/compressed_encrypted.dat'
    EXEC sp_OAMethod @compress, 'CompressEncryptFile', @success OUT, @json, @inPath, @outPath
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @compress, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @compress
        EXEC @hr = sp_OADestroy @json
        RETURN
      END

    -- We can do file-to-file decrypt/decompress like this:
    DECLARE @inPath2 nvarchar(4000)
    SELECT @inPath2 = @outPath
    DECLARE @outPath2 nvarchar(4000)
    SELECT @outPath2 = 'c:/temp/qa_output/restored.dat'
    EXEC sp_OAMethod @compress, 'DecryptDecompressFile', @success OUT, @json, @inPath2, @outPath2
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @compress, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @compress
        EXEC @hr = sp_OADestroy @json
        RETURN
      END

    -- Note: The above decrypt + decompress is the equivalent of doing the same in these two steps:
    DECLARE @crypt int
    EXEC @hr = sp_OACreate 'Chilkat.Crypt2', @crypt OUT

    EXEC sp_OASetProperty @crypt, 'CryptAlgorithm', 'aes'
    EXEC sp_OASetProperty @crypt, 'CipherMode', 'cbc'
    EXEC sp_OASetProperty @crypt, 'KeyLength', 128
    EXEC sp_OASetProperty @crypt, 'PaddingScheme', 0
    EXEC sp_OAMethod @crypt, 'SetEncodedIV', NULL, '000102030405060708090A0B0C0D0E0F', 'hex'
    EXEC sp_OAMethod @crypt, 'SetEncodedKey', NULL, '000102030405060708090A0B0C0D0E0F', 'hex'

    DECLARE @decryptedPath nvarchar(4000)
    SELECT @decryptedPath = 'c:/temp/qa_output/decrypted.dat'
    EXEC sp_OAMethod @crypt, 'CkDecryptFile', @success OUT, @inPath2, @decryptedPath
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @crypt, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @compress
        EXEC @hr = sp_OADestroy @json
        EXEC @hr = sp_OADestroy @crypt
        RETURN
      END

    DECLARE @outPath3 nvarchar(4000)
    SELECT @outPath3 = 'c:/temp/qa_output/restored_in_two_steps.dat'
    EXEC sp_OAMethod @compress, 'DecompressFile', @success OUT, @decryptedPath, @outPath3
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @compress, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @compress
        EXEC @hr = sp_OADestroy @json
        EXEC @hr = sp_OADestroy @crypt
        RETURN
      END


    PRINT 'Success.'

    EXEC @hr = sp_OADestroy @compress
    EXEC @hr = sp_OADestroy @json
    EXEC @hr = sp_OADestroy @crypt


END
GO