Messages in this thread | | | From | "Jason A. Donenfeld" <> | Date | Fri, 20 Jan 2017 06:27:19 +0100 | Subject | Re: [PATCH 1/2] random: use chacha20 for get_random_int/long |
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Hi Ted,
On Wed, Jan 18, 2017 at 4:49 AM, Theodore Ts'o <tytso@mit.edu> wrote: > You're using a union for the entropy_u64 and entropy_u32 arrays, and > the position field is used to indexed into those two arrays. > > So if the first caller calls get_random_u64 with position=0, it will > get the first 64 bits out of the batched entropy, and increment the > position to 1. If the second caller calls get_random_u32 with > position=1... it will get the second of the 32-bit chunks in the > batched entropy array --- which will include the 64 bits returned to > the first caller.
This is most certainly not the case. Read closely.
I use a different variable for each function. get_random_u32 only touches batched_entropy_u32, and get_random_u64 only touches bached_entropy_u64. Under no circumstances will one function use the other's batched entropy.
I use a union so that only one struct must be declared. If you think that's unclear, I can declare two separate structs instead. Let me know which strategy you prefer -- what I have now, or splitting it into two structs.
Jason
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