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(SQL Server) Streaming Encryption by Encrypting in ChunksEncrypt data in chunks.
-- 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 @crypt int EXEC @hr = sp_OACreate 'Chilkat.Crypt2', @crypt OUT IF @hr <> 0 BEGIN PRINT 'Failed to create ActiveX component' RETURN END EXEC sp_OASetProperty @crypt, 'CryptAlgorithm', 'aes' EXEC sp_OASetProperty @crypt, 'CipherMode', 'cbc' EXEC sp_OASetProperty @crypt, 'KeyLength', 128 EXEC sp_OAMethod @crypt, 'SetEncodedKey', NULL, '000102030405060708090A0B0C0D0E0F', 'hex' EXEC sp_OAMethod @crypt, 'SetEncodedIV', NULL, '000102030405060708090A0B0C0D0E0F', 'hex' EXEC sp_OASetProperty @crypt, 'EncodingMode', 'hex' DECLARE @txt1 nvarchar(4000) SELECT @txt1 = 'The quick brown fox jumped over the lazy dog.' + CHAR(13) + CHAR(10) DECLARE @txt2 nvarchar(4000) SELECT @txt2 = '-' + CHAR(13) + CHAR(10) DECLARE @txt3 nvarchar(4000) SELECT @txt3 = 'Done.' + CHAR(13) + CHAR(10) DECLARE @sbEncrypted int EXEC @hr = sp_OACreate 'Chilkat.StringBuilder', @sbEncrypted OUT -- Encrypt the 1st chunk: -- (don't worry about feeding the data to the encryptor in -- exact multiples of the encryption algorithm's block size. -- Chilkat will buffer the data.) EXEC sp_OASetProperty @crypt, 'FirstChunk', 1 EXEC sp_OASetProperty @crypt, 'LastChunk', 0 DECLARE @success int EXEC sp_OAMethod @crypt, 'EncryptStringENC', @sTmp0 OUT, @txt1 EXEC sp_OAMethod @sbEncrypted, 'Append', @success OUT, @sTmp0 -- Encrypt the 2nd chunk EXEC sp_OASetProperty @crypt, 'FirstChunk', 0 EXEC sp_OASetProperty @crypt, 'LastChunk', 0 EXEC sp_OAMethod @crypt, 'EncryptStringENC', @sTmp0 OUT, @txt2 EXEC sp_OAMethod @sbEncrypted, 'Append', @success OUT, @sTmp0 -- Now encrypt N more chunks... -- Remember -- we're doing this in CBC mode, so each call -- to the encrypt method depends on the state from previous -- calls... EXEC sp_OASetProperty @crypt, 'FirstChunk', 0 EXEC sp_OASetProperty @crypt, 'LastChunk', 0 DECLARE @i int SELECT @i = 0 WHILE @i <= 4 BEGIN EXEC sp_OAMethod @crypt, 'EncryptStringENC', @sTmp0 OUT, @txt1 EXEC sp_OAMethod @sbEncrypted, 'Append', @success OUT, @sTmp0 EXEC sp_OAMethod @crypt, 'EncryptStringENC', @sTmp0 OUT, @txt2 EXEC sp_OAMethod @sbEncrypted, 'Append', @success OUT, @sTmp0 SELECT @i = @i + 1 END -- Now encrypt the last chunk: EXEC sp_OASetProperty @crypt, 'FirstChunk', 0 EXEC sp_OASetProperty @crypt, 'LastChunk', 1 EXEC sp_OAMethod @crypt, 'EncryptStringENC', @sTmp0 OUT, @txt3 EXEC sp_OAMethod @sbEncrypted, 'Append', @success OUT, @sTmp0 EXEC sp_OAMethod @sbEncrypted, 'GetAsString', @sTmp0 OUT PRINT @sTmp0 -- Now decrypt in one call. -- (The data we're decrypting is both the first AND last chunk.) EXEC sp_OASetProperty @crypt, 'FirstChunk', 1 EXEC sp_OASetProperty @crypt, 'LastChunk', 1 DECLARE @decryptedText nvarchar(4000) EXEC sp_OAMethod @sbEncrypted, 'GetAsString', @sTmp0 OUT EXEC sp_OAMethod @crypt, 'DecryptStringENC', @decryptedText OUT, @sTmp0 PRINT @decryptedText -- Note: You may decrypt in N chunks by setting the FirstChunk -- and LastChunk properties prior to calling the Decrypt* methods EXEC @hr = sp_OADestroy @crypt EXEC @hr = sp_OADestroy @sbEncrypted END GO |
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