[erlang-questions] Use new crypto functions

pablo platt <>
Tue Nov 19 16:33:01 CET 2013


Hi,

I had to remove the 32 bits size tag from ?DH_P, ?DH_G too.
Now it's working.

Thank you.



On Tue, Nov 19, 2013 at 4:54 PM, Ingela Andin <>wrote:

> Hi!
>
> The new API does not want any mpints (binaries with size tags) so if you
> hade mpints as input you will have to remove the size tag. If you used
> erlang integers there will not be any need to make any changes.
>
> Regards Ingela Erlang/OTP team - Ericsson AB
>
>
> 2013/11/19 pablo platt <>
>
>> Hi,
>>
>> I'm trying to replace the deprecated crypto functions dh_generate_key/1
>> and dh_compute_key/3 with the new functions generate_key/2 and
>> compute_key/3 but my app fails.
>>
>> The byte_size of the results are different between the old and new API:
>> Old:
>> PublicKey - 132 Bytes
>> PrivateKey - 132 Bytes
>> Shared - 128 Bytes
>>
>> New
>> PublicKey - 129 Bytes
>> PrivateKey - 129 Bytes
>> Shared - 129 Bytes
>>
>> Shouldn't the functionality and the size of the keys be the same?
>> Do I need to change something to make it work?
>>
>> Code:
>>
>> Old functions:
>> {PublicKey, PrivateKey} = crypto:dh_generate_key([?DH_P, ?DH_G]),
>> Shared = crypto:dh_compute_key(ClientKey, PrivateKey, [?DH_P, ?DH_G]),
>> <<_:32, PublicKey2/binary>> = PublicKey. % Needed for my app with the old
>> API
>>
>> New functions:
>> {PublicKey, PrivateKey} = crypto:generate_key(dh, [?DH_P, ?DH_G]),
>> Shared = crypto:compute_key(dh, ClientKey, PrivateKey, [?DH_P, ?DH_G]),
>> <<_:32, PublicKey2/binary>> = PublicKey.
>>
>> % ?DH_P size is 132 Bytes
>> % ?DH_G size is 5 Bytes
>>
>> Thanks
>>
>> _______________________________________________
>> erlang-questions mailing list
>> 
>> http://erlang.org/mailman/listinfo/erlang-questions
>>
>>
>
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