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RIOT/sys/include/psa_crypto/psa/key/lifetime.h
Armin Wolf dd81d185cd sys/psa_crypto: Split key definitions into separate files 
Split key definitions into separate files, together with some basic
support macros.

This allows PSA crypto backends to use this definitions without
pulling in all the other type definitions.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
2024-11-26 20:01:09 +01:00

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/*
* Copyright (C) 2024 TU Dresden
* Copyright (C) 2021 HAW Hamburg
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup sys_psa_crypto
* @{
*
* @file key/lifetime.h
* @brief Key ilfetime definitions for the PSA Crypto API
*
* @author Armin Wolf <wolf.armin@mailbox.tu-dresden.de>
* @author Lena Boeckmann <lena.boeckmann@haw-hamburg.de>
*
*/
#ifndef PSA_CRYPTO_PSA_KEY_LIFETIME_H
#define PSA_CRYPTO_PSA_KEY_LIFETIME_H
#ifdef __cplusplus
extern "C" {
#endif
#include <stdint.h>
/**
* @brief Encoding of key lifetimes.
*
* @details The lifetime of a key indicates where it is stored and which application and system
* actions will create and destroy it.
*
* Lifetime values have the following structure:
* - Bits[7:0]: Persistence level
* This value indicates what device management actions can cause it to be destroyed.
* In particular, it indicates whether the key is volatile or persistent.
* See @ref psa_key_persistence_t for more information.
* @ref PSA_KEY_LIFETIME_GET_PERSISTENCE(@p lifetime) returns the persistence level for
* a key lifetime value.
* - Bits[31:8]: Location indicator
* This value indicates where the key material is stored (or at least where it is
* accessible in cleartext) and where operations on the key are performed. See
* @ref psa_key_location_t for more information.
* @ref PSA_KEY_LIFETIME_GET_LOCATION(@p lifetime) returns the location indicator for a
* key lifetime value.
*
* Volatile keys are automatically destroyed when the application instance terminates or
* on a power reset of the device. Persistent keys are preserved until the application
* explicitly destroys them or until an implementation-specific device management event
* occurs, for example, a factor reset.
*
* Persistent keys have a key identifier of type @ref psa_key_id_t. This identifier
* remains valid throughout the lifetime of the key, even if the application instance
* that created the key terminates.
*
* This specification defines two basic lifetime values:
* - Keys with the lifetime @ref PSA_KEY_LIFETIME_VOLATILE are volatile. All
* implementations should support this lifetime.
* - Keys with the lifetime @ref PSA_KEY_LIFETIME_PERSISTENT are persistent. All
* implementations that have access to persistent storage with appropriate security
* guarantees should support this lifetime.
*/
typedef uint32_t psa_key_lifetime_t;
/**
* @brief Encoding of key persistence levels.
*
* @details What distinguishes different persistence levels is which device management events can
* cause keys to be destroyed. For example, power reset, transfer of device ownership,
* or a factory reset are device management events that can affect keys at different
* persistence levels. The specific management events which affect persistent keys at
* different levels is outside the scope of the PSA Cryptography specification.
*
* @note Key persistence levels are 8-bit values. Key management interfaces operate on lifetimes
* (type @ref psa_key_lifetime_t), and encode the persistence value as the lower 8 bits of
* a 32-bit value.
*
* Values for persistence levels defined by this specification are shown below:
* - @c 0 = @ref PSA_KEY_PERSISTENCE_VOLATILE : Volatile key.
* A volatile key is automatically destroyed by the implementation when the
* application instance terminates. In particular, a volatile key is
* automatically destroyed on a power reset of the device.
* - @c 1 = @ref PSA_KEY_PERSISTENCE_DEFAULT : Persistent key with a default lifetime.
* Implementations should support this value if they support persistent keys
* at all. Applications should use this value if they have no specific needs
* that are only met by implementation-specific features.
* - @c 2–127: Persistent key with a PSA-specified lifetime. The PSA Cryptography
* specification does not define the meaning of these values, but other PSA
* specifications may do so.
* - @c 128–254: Persistent key with a vendor-specified lifetime. No PSA specification
* will define the meaning of these values, so implementations may choose
* the meaning freely. As a guideline, higher persistence levels should
* cause a key to survive more management events than lower levels.
* - @c 255 = @ref PSA_KEY_PERSISTENCE_READ_ONLY : Read-only or write-once key.
* A key with this persistence level cannot be destroyed. Implementations that
* support such keys may either allow their creation through the PSA
* Cryptography API, preferably only to applications with the appropriate
* privilege, or only expose keys created through implementation-specific
* means such as a factory ROM engraving process.
* @note Keys that are read-only due to policy restrictions rather than
* due to physical limitations should not have this persistence level.
*/
typedef uint8_t psa_key_persistence_t;
/**
* @brief Encoding of key location indicators.
*
* @details If an implementation of this API can make calls to external cryptoprocessors such as
* secure elements, the location of a key indicates which secure element performs the
* operations on the key. If the key material is not stored persistently inside the secure
* element, it must be stored in a wrapped form such that only the secure element can
* access the key material in cleartext.
*
* @note Key location indicators are 24-bit values. Key management interfaces operate on
* lifetimes (type @ref psa_key_lifetime_t), and encode the location as the upper 24 bits
* of a 32-bit value.
*
* Values for location indicators defined by this specification are shown below:
* - @c 0: Primary local storage.
* All implementations should support this value. The primary local storage is
* typically the same storage area that contains the key metadata.
* - @c 1: Primary secure element.
* @note As of now, this value is not supported by this implementation.
* Use the vendor-defined location values.
*
* Implementations should support this value if there is a secure element
* attached to the operating environment. As a guideline, secure elements may
* provide higher resistance against side channel and physical attacks than the
* primary local storage, but may have restrictions on supported key types,
* sizes, policies and operations and may have different performance
* characteristics.
* - @c 2–0x7fffff: Other locations defined by a PSA specification.
* The PSA Cryptography API does not currently assign any meaning to
* these locations, but future versions of this specification or other
* PSA specifications may do so.
* - @c 0x800000–0xffffff: Vendor-defined locations. No PSA specification will assign a
* meaning to locations in this range.
*/
typedef uint32_t psa_key_location_t;
/**
* @brief The default lifetime for volatile keys.
*
* @details A volatile key only exists as long as its identifier is not destroyed. The key material
* is guaranteed to be erased on a power reset.
*
* A key with this lifetime is typically stored in the RAM area of the PSA Crypto
* subsystem. However this is an implementation choice. If an implementation stores data
* about the key in a non-volatile memory, it must release all the resources associated
* with the key and erase the key material if the calling application terminates.
*/
#define PSA_KEY_LIFETIME_VOLATILE ((psa_key_lifetime_t)0x00000000)
/**
* @brief The default lifetime for persistent keys.
*
* @details A persistent key remains in storage until it is explicitly destroyed or until the
* corresponding storage area is wiped. This specification does not define any mechanism
* to wipe a storage area. Implementations are permitted to provide their own mechanism,
* for example, to perform a factory reset, to prepare for device refurbishment, or to
* uninstall an application.
*
* This lifetime value is the default storage area for the calling application.
* Implementations can offer other storage areas designated by other lifetime values as
* implementation-specific extensions.
*/
#define PSA_KEY_LIFETIME_PERSISTENT ((psa_key_lifetime_t)0x00000001)
/**
* @brief The persistence level of volatile keys.
*
* @details See @ref psa_key_persistence_t for more information.
*/
#define PSA_KEY_PERSISTENCE_VOLATILE ((psa_key_persistence_t)0x00)
/**
* @brief The default persistence level for persistent keys.
*
* @details See @ref psa_key_persistence_t for more information.
*/
#define PSA_KEY_PERSISTENCE_DEFAULT ((psa_key_persistence_t)0x01)
/**
* @brief A persistence level indicating that a key is never destroyed.
*
* @details See @ref psa_key_persistence_t for more information.
*/
#define PSA_KEY_PERSISTENCE_READ_ONLY ((psa_key_persistence_t)0xff)
/**
* @brief The local storage area for persistent keys.
*
* @details This storage area is available on all systems that can store persistent keys without
* delegating the storage to a third-party cryptoprocessor.
*
* See @ref psa_key_location_t for more information.
*/
#define PSA_KEY_LOCATION_LOCAL_STORAGE ((psa_key_location_t)0x000000)
/**
* @brief The default secure element storage area for persistent keys.
*
* @details This storage location is available on systems that have one or more secure elements
* that are able to store keys.
*
* Vendor-defined locations must be provided by the system for storing keys in additional
* secure elements.
*
* See @ref psa_key_location_t for more information.
*/
#define PSA_KEY_LOCATION_PRIMARY_SECURE_ELEMENT ((psa_key_location_t)0x000001)
/**
* @brief Mark vendor defined key locations
*/
#define PSA_KEY_LOCATION_VENDOR_FLAG ((psa_key_location_t)0x800000)
/**
* @brief Minimum location value for secure elements
*/
#define PSA_KEY_LOCATION_SE_MIN (PSA_KEY_LOCATION_VENDOR_FLAG)
/**
* @brief Maximum location value for secure elements
*/
#define PSA_KEY_LOCATION_SE_MAX ((psa_key_location_t)0x8000ff)
/**
* @brief Extract the persistence level from a key lifetime.
*
* @param lifetime The lifetime value to query: a value of type @ref psa_key_lifetime_t.
*/
#define PSA_KEY_LIFETIME_GET_PERSISTENCE(lifetime) \
((psa_key_persistence_t)((lifetime) & 0x000000ff))
/**
* @brief Extract the location indicator from a key lifetime.
*
* @param lifetime The lifetime value to query: a value of type @ref psa_key_lifetime_t.
*/
#define PSA_KEY_LIFETIME_GET_LOCATION(lifetime) \
((psa_key_location_t)((lifetime) >> 8))
/**
* @brief Whether a key lifetime indicates that the key is volatile.
*
* A volatile key is automatically destroyed by the implementation when the application
* instance terminates. In particular, a volatile key is automatically destroyed on a
* power reset of the device.
*
* A key that is not volatile is persistent. Persistent keys are preserved until the
* application explicitly destroys them or until an implementation-specific device
* management event occurs, for example, a factory reset.
*
* @param lifetime The lifetime value to query: a value of type @ref psa_key_lifetime_t.
*
* @return 1 if the key is volatile, otherwise 0.
*/
#define PSA_KEY_LIFETIME_IS_VOLATILE(lifetime) \
(PSA_KEY_LIFETIME_GET_PERSISTENCE(lifetime) == PSA_KEY_PERSISTENCE_VOLATILE)
/**
* @brief Construct a lifetime from a persistence level and a location.
*
* @param persistence The persistence level: a value of type @ref psa_key_persistence_t.
* @param location The location indicator: a value of type @ref psa_key_location_t.
*
* @return The constructed lifetime value.
*/
#define PSA_KEY_LIFETIME_FROM_PERSISTENCE_AND_LOCATION(persistence, location) \
((location) << 8 | (persistence))
#ifdef __cplusplus
}
#endif
#endif /* PSA_CRYPTO_PSA_KEY_LIFETIME_H */
/** @} */
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