Re: [Boost-users] Seeding boost::mt19937 with bytes from CryptoGenRandom

Subject: Re: [Boost-users] Seeding boost::mt19937 with bytes from CryptoGenRandom
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2010-02-11 11:17:31

AMDG

Ovanes Markarian wrote:
>> The memcpy should copy from randomBytes into seed.  (Assuming I
>> haven't forgotten the signature of memcpy.)
>>     
>
>
> Seems, like I forgot the signature... Another way to transfer the bytes
> would be:
>
> union bytes2seed
> {
>    uint64_t seed_;
>    char      bytes_[sizeof(uint64_t)];
> };
>
> bytes2seed converter;
>
> Now one can pass &converter.bytes_[0] to CryptGenRandom. This does not
> require an additional memcpy call.
>   

Casting through a union is undefined behavior.  :(.

In Christ,
Steven Watanabe