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It is not meaningful for reseed_entropy_size to be 0

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Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
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Gilles Peskine 2020-11-13 14:27:43 +01:00
parent 0e3b7ced4c
commit 390c5a2c6f
1 changed files with 5 additions and 5 deletions
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10
docs/proposed/psa-driver-interface.md
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@ -483,11 +483,11 @@ If no driver implements the random generation entry point family, the core provi
This operation family requires the following type, entry points and parameters (TODO: where exactly are the parameters in the JSON structure?):
* Type `"random_context_t"`: the type of a random generation context.
* `"init_random"` (optional): if this function is present, [the core calls it once](#random-generator-initialization) after allocating a `"random_context_t"` object.
* `"add_entropy"` (entry point): the core calls this function to [inject entropy](#entropy-injection).
* `"get_random"` (entry point): the core calls this function whenever it needs to [obtain random data](#the-get_random-entry-point).
* `"initial_entropy_size"` (integer): the minimum number of bytes of entropy that the core must supply before the driver can output random data. This can be `0` if the driver includes an entropy source of its own.
* `"reseed_entropy_size"` (integer): the minimum number of bytes of entropy that the core must supply when the driver runs out of entropy. This can be `0` if the driver includes an entropy source of its own.
* `"init_random"` (entry point, optional): if this function is present, [the core calls it once](#random-generator-initialization) after allocating a `"random_context_t"` object.
* `"add_entropy"` (entry point, mandatory): the core calls this function to [inject entropy](#entropy-injection).
* `"get_random"` (entry point, mandatory): the core calls this function whenever it needs to [obtain random data](#the-get_random-entry-point).
* `"initial_entropy_size"` (integer, optional): the minimum number of bytes of entropy that the core must supply before the driver can output random data. This can be `0` if the driver includes an entropy source of its own. If omitted, the value is `0`.
* `"reseed_entropy_size"` (integer, optional): the minimum number of bytes of entropy that the core must supply when the driver runs out of entropy. This value is also a hint for the size to supply if the core makes additional calls to `"add_entropy"`, for example to enforce prediction resistance. If omitted, the core chooses a value which is at least the expected security strength of the device.
Random generation is not parametrized by an algorithm. The choice of algorithm is up to the driver.