(SQL Server) openssl enc decrypt

Demonstrates how to decrypt a file that was encrypted using "openssl enc".

This example shows how to decrypt what was created using this openssl command:

openssl enc -e -aes-256-cbc -in hamlet.xml -out hamlet.enc -pass file:./secret.txt

This example shows how to do this:

openssl enc -d -aes-256-cbc -in hamlet.enc -out hamlet_dec.xml -pass file:./secret.txt

Note: This example requires Chilkat v11.1.0 or greater.

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)
    DECLARE @success int
    SELECT @success = 0

    -- 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

    -- Use aes-256-cbc
    EXEC sp_OASetProperty @crypt, 'CryptAlgorithm', 'aes'
    EXEC sp_OASetProperty @crypt, 'CipherMode', 'cbc'
    EXEC sp_OASetProperty @crypt, 'KeyLength', 256

    -- We'll need to set the hash algorithm to either MD5 or SHA256.
    -- openssl version 1.0.* or earlier used MD5 by default
    -- openssl version 1.1.* uses SHA-256 for the password to secret key derivation.

    -- For example, if openssl 1.1.0 was used, we should do this:
    EXEC sp_OASetProperty @crypt, 'HashAlgorithm', 'sha256'

    -- This example assumes openssl 1.0.2 was used to encrypt what we're now decrypting:
    EXEC sp_OASetProperty @crypt, 'HashAlgorithm', 'md5'

    -- The openssl command we are duplicating is:
    -- 
    --    openssl enc -d -aes-256-cbc -in hamlet.enc -out hamlet_dec.xml -pass file:./secret.txt
    -- 
    -- The file secret.txt contains the word "secret".  We could write code to load the contents
    -- of secret.txt, but instead we'll just do this:
    EXEC sp_OAMethod @crypt, 'SetEncodedKey', NULL, 'secret', 'openssl'

    -- Load the file to be decrypted.
    DECLARE @fileData int
    EXEC @hr = sp_OACreate 'Chilkat.BinData', @fileData OUT

    EXEC sp_OAMethod @fileData, 'LoadFile', @success OUT, 'qa_data/openssl_enc/hamlet.enc'

    -- Decrypt
    EXEC sp_OASetProperty @crypt, 'VerboseLogging', 1
    EXEC sp_OAMethod @crypt, 'DecryptBd', @success OUT, @fileData
    EXEC sp_OAGetProperty @crypt, 'LastErrorText', @sTmp0 OUT
    PRINT @sTmp0

    -- Save the decrypted output.
    EXEC sp_OAMethod @fileData, 'WriteFile', @success OUT, 'c:/temp/qa_output/hamlet_dec.xml'


    PRINT 'success = ' + @success

    EXEC @hr = sp_OADestroy @crypt
    EXEC @hr = sp_OADestroy @fileData


END
GO