[vlc-devel] [PATCH] Simplify vlc_rand_bytes on Windows

[Steve Lhomme]

I created this merge request: 
https://code.videolan.org/videolan/vlc/-/merge_requests/5366

On 08/04/2024 07:26, Steve Lhomme wrote:
> Hello,
> 
> Can you open a merge request on https://code.videolan.org/videolan/vlc ?
> 
> Thanks
> 
> On 05/04/2024 17:46, visuve wrote:
>> - Use system preferred RNG and skip the unnecessary initialization 
>> steps (in this context, which is definitely not security related)
>> - The vlc_rand_bytes function is now about 55x faster when called 
>> repeatedly in a loop
>> - See 
>> https://learn.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom for more details
>> ---
>>   src/win32/rand.c | 9 +--------
>>   1 file changed, 1 insertion(+), 8 deletions(-)
>>
>> diff --git a/src/win32/rand.c b/src/win32/rand.c
>> index 54cbe3c5..25a0c668 100644
>> --- a/src/win32/rand.c
>> +++ b/src/win32/rand.c
>> @@ -30,12 +30,5 @@
>>   void vlc_rand_bytes (void *buf, size_t len)
>>   {
>> -    BCRYPT_ALG_HANDLE algo_handle;
>> -    NTSTATUS ret = BCryptOpenAlgorithmProvider(&algo_handle, 
>> BCRYPT_RNG_ALGORITHM,
>> -                                               MS_PRIMITIVE_PROVIDER, 
>> 0);
>> -    if (BCRYPT_SUCCESS(ret))
>> -    {
>> -        BCryptGenRandom(algo_handle, buf, len, 0);
>> -        BCryptCloseAlgorithmProvider(algo_handle, 0);
>> -    }
>> +    BCryptGenRandom(nullptr, buf, len, BCRYPT_USE_SYSTEM_PREFERRED_RNG);
>>   }
>> -- 
>> 2.43.0.windows.1
>>
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