[Haskell-cafe] How to use an crypto with hackage cereal?

[Magicloud Magiclouds]

How about fail in Get monad if decrypt failed? So decrypt failure would
lead to a result of "Left String" on decode.

On Wed, Apr 22, 2015 at 11:05 AM, Andrey Sverdlichenko <blaze at ruddy.ru>
wrote:

> You probably should not merge decrypt and decode operations, it is bad
> crypto habit. Until you decrypted and verified integrity of data, parsing
> is dangerous and opening your service to attacks. Correct way of
> implementing this would be to pass ciphertext to decryption function and
> run parser only if decryption is successful. If bytestring is too big to be
> decrypted in one piece, consider encrypting it in blocks and feeding
> decrypted parts to parser.
>
>
>
> On Tue, Apr 21, 2015 at 7:49 PM, Magicloud Magiclouds <
> magicloud.magiclouds at gmail.com> wrote:
>
>> Similar as you envisaged. I would receive a bytestring data and a config
>> point out what cipher to use. Then I deserialize the data to a data type
>> with some fields. The serialize process is something like:
>>
>> msum $ map (encrypt . encode) [field1, field2, field3]
>>
>> I could parse the bytestring outside Get/Put monads. But I think that
>> looks ugly. I really want to embed the decrypt process into Get/Put monads.
>>
>> On Tue, Apr 21, 2015 at 10:08 PM, Ivan Lazar Miljenovic <
>> ivan.miljenovic at gmail.com> wrote:
>>
>>> On 21 April 2015 at 23:58, Magicloud Magiclouds
>>> <magicloud.magiclouds at gmail.com> wrote:
>>> > Thank you. But how if the cipher was specified outside the binary
>>> data? I
>>> > mean I need to pass the decrypt/encrypt function to get/put while they
>>> do
>>> > not accept parameters. Should I use Reader here?
>>>
>>> Maybe you could explain what you're doing better.
>>>
>>> I would envisage that you would get a Bytestring/Text value, then
>>> encrypt/decrypt and then put it back (though if you're dealing with
>>> Bytestrings, unless you're wanting to compose them with others there's
>>> no real need to use Get and Put as you'll have the resulting
>>> Bytestring already...).
>>>
>>> Or are you wanting to implement your own encryption/decryption scheme?
>>>  In which case, you might want to either:
>>>
>>> a) write custom functions in the Get and Put monads OR
>>>
>>> b) write custom parsers (e.g. attoparsec) and builders (using the
>>> Builder module in bytestring); this is probably going to suit you
>>> better.
>>>
>>> >
>>> > On Tue, Apr 21, 2015 at 6:43 PM, Yitzchak Gale <gale at sefer.org> wrote:
>>> >>
>>> >> Magicloud Magiclouds wrote:
>>> >> > I am trying to work with some binary data that encrypted by field
>>> >> > instead of
>>> >> > the result of serialization. I'd like to use Data.Serialize to wrap
>>> the
>>> >> > data
>>> >> > structure. But I could not figure out how to apply an runtime
>>> specified
>>> >> > cipher method to the bytestring.
>>> >>
>>> >> Are you using the set of crypto libraries written by
>>> >> Victor Hanquez, such as cryptocipher-types,
>>> >> crypto-pubkey-types, and cryptohash?
>>> >>
>>> >> Or the set of libraries written by Thomas DuBuisson,
>>> >> such as crypto-api, cipher-aes128, etc.?
>>> >>
>>> >> Here is an example of decoding for Victor's libraries.
>>> >> Encoding would be similar using Put instead of Get.
>>> >> Thomas' libraries would be similar using the other
>>> >> API.
>>> >>
>>> >> Let's say you have a type like this:
>>> >>
>>> >> data MyCipher = MyAES | MyBlowfish | ...
>>> >>
>>> >> Then in your cereal code you would have a Get monad
>>> >> expression something like this (assuming you have
>>> >> written all of the functions called parseSomething):
>>> >>
>>> >> getStuff = do
>>> >>   cipher <- parseCipher :: Get MyCipher
>>> >>   clearText <- case cipher of
>>> >>     MyAES -> do
>>> >>       keyBS <- parseAESKey :: Get ByteString
>>> >>       let key = either (error "bad AES key") id $ makeKey keyBS
>>> >>           cipher = cipherInit key
>>> >>       cipherText <- parseAESCipherText :: Get ByteString
>>> >>       return $ ecbDecrypt cipher cipherText
>>> >>     MyBlowfish -> do ...
>>> >>
>>> >> etc.
>>> >>
>>> >> Hope this helps,
>>> >> Yitz
>>> >
>>> >
>>> >
>>> >
>>> > --
>>> > 竹密岂妨流水过
>>> > 山高哪阻野云飞
>>> >
>>> > And for G+, please use magiclouds#gmail.com.
>>> >
>>> > _______________________________________________
>>> > Haskell-Cafe mailing list
>>> > Haskell-Cafe at haskell.org
>>> > http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
>>> >
>>>
>>>
>>>
>>> --
>>> Ivan Lazar Miljenovic
>>> Ivan.Miljenovic at gmail.com
>>> http://IvanMiljenovic.wordpress.com
>>>
>>
>>
>>
>> --
>> 竹密岂妨流水过
>> 山高哪阻野云飞
>>
>> And for G+, please use magiclouds#gmail.com.
>>
>
>


-- 
竹密岂妨流水过
山高哪阻野云飞

And for G+, please use magiclouds#gmail.com.
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