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39db721f9a
This function will be used to generate some entropy using the
Clock Recovery System.
BRANCH=none
BUG=b:38486828
TEST=make BOARD=hammer -j tests
./util/flash_ec --board=hammer --image=build/hammer/test-entropy.bin
EC console: runtest
TEST=Test fails when no USB connection is active
TEST=Test passes when USB connection is active
TEST=Pasting the values into:
tr ';' '\n' | awk 'BEGIN { e = 0; tot=16384.0 }
{ p = $1/tot; if (p > 0) { e -= p*log(p)/log(2) } }
END { print e }'
shows an entropy > 4 bits per sample.
Change-Id: I2363c7bce42c72c33ef0bf3f099d709ee9c13d13
Reviewed-on: https://chromium-review.googlesource.com/518608
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
/* Copyright 2017 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef __CROS_EC_ROLLBACK_H
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#define __CROS_EC_ROLLBACK_H
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#define CROS_EC_ROLLBACK_COOKIE 0x0b112233
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#ifndef __ASSEMBLER__
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/**
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* Get minimum version set by rollback protection blocks.
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*
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* @return Minimum rollback version, 0 if neither block is initialized,
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* negative value on error.
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*/
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int rollback_get_minimum_version(void);
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/**
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* Update rollback protection block to the version passed as parameter.
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*
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* @param next_min_version Minimum version to write in rollback block.
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*
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* @return EC_SUCCESS on success, EC_ERROR_* on error.
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*/
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int rollback_update_version(int32_t next_min_version);
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/**
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* Add entropy to the rollback block.
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*
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* @param data Data to be added to rollback block secret (after hashing)
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* @param len data length
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*
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* @return EC_SUCCESS on success, EC_ERROR_* on error.
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*/
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int rollback_add_entropy(uint8_t *data, unsigned int len);
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/**
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* Lock rollback protection block, reboot if necessary.
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*
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* @return EC_SUCCESS if rollback was already protected.
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*/
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int rollback_lock(void);
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/**
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* Obtain some weak entropy (i.e. not guaranteed to be high quality), based on
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* sensors or timing events.
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*
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* Must be defined if CONFIG_ROLLBACK_SECRET_SIZE is set. May sleep.
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*
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* @param buffer Buffer to fill with entropy.
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* @param len Buffer length.
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*
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* @return true if the buffer was filled, false on error.
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*/
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int board_get_entropy(void *buffer, int len);
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#endif
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#endif /* __CROS_EC_ROLLBACK_H */
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