# Obtain Raw Noise Data

This tool offers the collection of raw entropy from the running Linux
kernel Jitter RNG, compliant to SP800-90B section 3.1.3

To obtain raw noise data from the Jitter RNG, follow these steps:

1. Ensure patch providing kernel Jitter RNG test interface is applied,
   select `CONFIG_CRYPTO_JITTERENTROPY_TESTINTERFACE`, compile, install and
   reboot the kernel - if you want to stimulate the generation of entropy
   with the command below, ensure the kernel option
   `CONFIG_CRYPTO_USER_API_RNG` is set to `m` or `y`.

2. Compile getrawentropy.c as documented in that file.

   NOTE: Starting from 6.13, the data size storing raw entropy has changed from
   `u32` to `u64` in the kernel (see `crypto/jitterentropy-testing.c` and
   check the data type of the variable `jent_testing_rb`). When the data type is
   set to `u64` you MUST compile the tool with `-DRAW_DATATYPE_U64`.

3. Execute as root to obtain the raw entropy data:
	`getrawentropy -f /sys/kernel/debug/jitterentropy_testing/jent_raw_hires -s 1000001 > /dev/shm/jent-raw-noise-0001.data`

4. In parallel to step 3, stimulate the generation of entropy, e.g. by using
   the following command with a tool from libkcapi using the following command
	`kcapi-rng -n "jitterentropy_rng" -b 2000000 > /dev/null`

5. Process the obtained data with validation-runtime-kernel/processdata.sh

   NOTE: The generated output is already in the correct format for
   processdata.sh and does not need to be converted any more.
