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

[Erik Hesselink]

One thing I've done in the past is, instead of giving an 'instance
Serialize YourType', give an 'instance Serialize (Input -> YourType)'.
This way you can get access to the input in the instance, but you have
to provide the input when you can the deserialization function.

Regards,

Erik

On Tue, Apr 21, 2015 at 3:58 PM, 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?
>
> 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
>
>
>
>
> --
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