Mbed OS Reference | crypto_types.h Source File

 /*
  * Copyright (c) 2018-2021, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  *
  */
 /**
  * \file psa/crypto_types.h
  *
  * \brief PSA cryptography module: type aliases.
  *
  * \note This file may not be included directly. Applications must
  * include psa/crypto.h. Drivers must include the appropriate driver
  * header file.
  *
  * This file contains portable definitions of integral types for properties
  * of cryptographic keys, designations of cryptographic algorithms, and
  * error codes returned by the library.
  *
  * This header file does not declare any function.
  */
 
 #ifndef PSA_CRYPTO_TYPES_H
 #define PSA_CRYPTO_TYPES_H
 
 #include <stdint.h>
 
 /** \defgroup error Error codes
  * @{
  */
 
 /**
  * \brief Function return status.
  *
  * This is either #PSA_SUCCESS (which is zero), indicating success,
  * or a small negative value indicating that an error occurred. Errors are
  * encoded as one of the \c PSA_ERROR_xxx values defined here. */
 /* If #PSA_SUCCESS is already defined, it means that #psa_status_t
  * is also defined in an external header, so prevent its multiple
  * definition.
  */
 #ifndef PSA_SUCCESS
 typedef int32_t psa_status_t;
 #endif
 
 /**@}*/
 
 /** \defgroup crypto_types Key and algorithm types
  * @{
  */
 
 /** \brief Encoding of a key type.
  */
 typedef uint16_t psa_key_type_t;
 
 /** The type of PSA elliptic curve family identifiers.
  *
  * The curve identifier is required to create an ECC key using the
  * PSA_KEY_TYPE_ECC_KEY_PAIR() or PSA_KEY_TYPE_ECC_PUBLIC_KEY()
  * macros.
  *
  * Values defined by this standard will never be in the range 0x80-0xff.
  * Vendors who define additional families must use an encoding in this range.
  */
 typedef uint8_t psa_ecc_family_t;
 
 /** The type of PSA Diffie-Hellman group family identifiers.
  *
  * The group identifier is required to create an Diffie-Hellman key using the
  * PSA_KEY_TYPE_DH_KEY_PAIR() or PSA_KEY_TYPE_DH_PUBLIC_KEY()
  * macros.
  *
  * Values defined by this standard will never be in the range 0x80-0xff.
  * Vendors who define additional families must use an encoding in this range.
  */
 typedef uint8_t psa_dh_family_t;
 
 /** \brief Encoding of a cryptographic algorithm.
  *
  * For algorithms that can be applied to multiple key types, this type
  * does not encode the key type. For example, for symmetric ciphers
  * based on a block cipher, #psa_algorithm_t encodes the block cipher
  * mode and the padding mode while the block cipher itself is encoded
  * via #psa_key_type_t.
  */
 typedef uint32_t psa_algorithm_t;
 
 /**@}*/
 
 /** \defgroup key_lifetimes Key lifetimes
  * @{
  */
 
 /** Encoding of key lifetimes.
  *
  * The lifetime of a key indicates where it is stored and what system actions
  * may create and destroy it.
  *
  * Lifetime values have the following structure:
  * - Bits 0-7 (#PSA_KEY_LIFETIME_GET_PERSISTENCE(\c lifetime)):
  *   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 ::psa_key_persistence_t for more information.
  * - Bits 8-31 (#PSA_KEY_LIFETIME_GET_LOCATION(\c lifetime)):
  *   location indicator. This value indicates which part of the system
  *   has access to the key material and can perform operations using the key.
  *   See ::psa_key_location_t for more information.
  *
  * 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
  * integration-specific device management event occurs (for example,
  * a factory reset).
  *
  * Persistent keys have a key identifier of type #psa_key_id_t.
  * This identifier remains valid throughout the lifetime of the key,
  * even if the application instance that created the key terminates.
  * The application can call psa_open_key() to open a persistent key that
  * it created previously.
  *
  * The default lifetime of a key is #PSA_KEY_LIFETIME_VOLATILE. The lifetime
  * #PSA_KEY_LIFETIME_PERSISTENT is supported if persistent storage is
  * available. Other lifetime values may be supported depending on the
  * library configuration.
  */
 typedef uint32_t psa_key_lifetime_t;
 
 /** Encoding of key persistence levels.
  *
  * What distinguishes different persistence levels is what device management
  * events may cause keys to be destroyed. _Volatile_ keys are destroyed
  * by a power reset. Persistent keys may be destroyed by events such as
  * a transfer of ownership or a factory reset. What management events
  * actually affect persistent keys at different levels is outside the
  * scope of the PSA Cryptography specification.
  *
  * The PSA Cryptography specification defines the following values of
  * persistence levels:
  * - \c 0 = #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 = #PSA_KEY_PERSISTENCE_DEFAULT:
  *   persistent key with a default lifetime.
  * - \c 2-254: currently not supported by Mbed TLS.
  * - \c 255 = #PSA_KEY_PERSISTENCE_READ_ONLY:
  *   read-only or write-once key.
  *   A key with this persistence level cannot be destroyed.
  *   Mbed TLS does not currently offer a way to create such keys, but
  *   integrations of Mbed TLS can use it for built-in keys that the
  *   application cannot modify (for example, a hardware unique key (HUK)).
  *
  * \note Key persistence levels are 8-bit values. Key management
  *       interfaces operate on lifetimes (type ::psa_key_lifetime_t) which
  *       encode the persistence as the lower 8 bits of a 32-bit value.
  */
 typedef uint8_t psa_key_persistence_t;
 
 /** Encoding of key location indicators.
  *
  * If an integration of Mbed TLS 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.
  * Depending on the design of the secure element, the key
  * material may be stored either in the secure element, or
  * in wrapped (encrypted) form alongside the key metadata in the
  * primary local storage.
  *
  * The PSA Cryptography API specification defines the following values of
  * location indicators:
  * - \c 0: primary local storage.
  *   This location is always available.
  *   The primary local storage is typically the same storage area that
  *   contains the key metadata.
  * - \c 1: primary secure element.
  *   Integrations of Mbed TLS 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 that 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.
  *
  * \note Key location indicators are 24-bit values. Key management
  *       interfaces operate on lifetimes (type ::psa_key_lifetime_t) which
  *       encode the location as the upper 24 bits of a 32-bit value.
  */
 typedef uint32_t psa_key_location_t;
 
 /** Encoding of identifiers of persistent keys.
  *
  * - Applications may freely choose key identifiers in the range
  *   #PSA_KEY_ID_USER_MIN to #PSA_KEY_ID_USER_MAX.
  * - The implementation may define additional key identifiers in the range
  *   #PSA_KEY_ID_VENDOR_MIN to #PSA_KEY_ID_VENDOR_MAX.
  * - 0 is reserved as an invalid key identifier.
  * - Key identifiers outside these ranges are reserved for future use.
  */
 typedef uint32_t psa_key_id_t;
 #define PSA_KEY_ID_INIT 0
 
 /**@}*/
 
 /** \defgroup policy Key policies
  * @{
  */
 
 /** \brief Encoding of permitted usage on a key. */
 typedef uint32_t psa_key_usage_t;
 
 /**@}*/
 
 /** \defgroup attributes Key attributes
  * @{
  */
 
 /** The type of a structure containing key attributes.
  *
  * This is an opaque structure that can represent the metadata of a key
  * object. Metadata that can be stored in attributes includes:
  * - The location of the key in storage, indicated by its key identifier
  *   and its lifetime.
  * - The key's policy, comprising usage flags and a specification of
  *   the permitted algorithm(s).
  * - Information about the key itself: the key type and its size.
  * - Additional implementation-defined attributes.
  *
  * The actual key material is not considered an attribute of a key.
  * Key attributes do not contain information that is generally considered
  * highly confidential.
  *
  * An attribute structure works like a simple data structure where each function
  * `psa_set_key_xxx` sets a field and the corresponding function
  * `psa_get_key_xxx` retrieves the value of the corresponding field.
  * However, a future version of the library  may report values that are
  * equivalent to the original one, but have a different encoding. Invalid
  * values may be mapped to different, also invalid values.
  *
  * An attribute structure may contain references to auxiliary resources,
  * for example pointers to allocated memory or indirect references to
  * pre-calculated values. In order to free such resources, the application
  * must call psa_reset_key_attributes(). As an exception, calling
  * psa_reset_key_attributes() on an attribute structure is optional if
  * the structure has only been modified by the following functions
  * since it was initialized or last reset with psa_reset_key_attributes():
  * - psa_set_key_id()
  * - psa_set_key_lifetime()
  * - psa_set_key_type()
  * - psa_set_key_bits()
  * - psa_set_key_usage_flags()
  * - psa_set_key_algorithm()
  *
  * Before calling any function on a key attribute structure, the application
  * must initialize it by any of the following means:
  * - Set the structure to all-bits-zero, for example:
  *   \code
  *   psa_key_attributes_t attributes;
  *   memset(&attributes, 0, sizeof(attributes));
  *   \endcode
  * - Initialize the structure to logical zero values, for example:
  *   \code
  *   psa_key_attributes_t attributes = {0};
  *   \endcode
  * - Initialize the structure to the initializer #PSA_KEY_ATTRIBUTES_INIT,
  *   for example:
  *   \code
  *   psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
  *   \endcode
  * - Assign the result of the function psa_key_attributes_init()
  *   to the structure, for example:
  *   \code
  *   psa_key_attributes_t attributes;
  *   attributes = psa_key_attributes_init();
  *   \endcode
  *
  * A freshly initialized attribute structure contains the following
  * values:
  *
  * - lifetime: #PSA_KEY_LIFETIME_VOLATILE.
  * - key identifier: 0 (which is not a valid key identifier).
  * - type: \c 0 (meaning that the type is unspecified).
  * - key size: \c 0 (meaning that the size is unspecified).
  * - usage flags: \c 0 (which allows no usage except exporting a public key).
  * - algorithm: \c 0 (which allows no cryptographic usage, but allows
  *   exporting).
  *
  * A typical sequence to create a key is as follows:
  * -# Create and initialize an attribute structure.
  * -# If the key is persistent, call psa_set_key_id().
  *    Also call psa_set_key_lifetime() to place the key in a non-default
  *    location.
  * -# Set the key policy with psa_set_key_usage_flags() and
  *    psa_set_key_algorithm().
  * -# Set the key type with psa_set_key_type().
  *    Skip this step if copying an existing key with psa_copy_key().
  * -# When generating a random key with psa_generate_key() or deriving a key
  *    with psa_key_derivation_output_key(), set the desired key size with
  *    psa_set_key_bits().
  * -# Call a key creation function: psa_import_key(), psa_generate_key(),
  *    psa_key_derivation_output_key() or psa_copy_key(). This function reads
  *    the attribute structure, creates a key with these attributes, and
  *    outputs a key identifier to the newly created key.
  * -# The attribute structure is now no longer necessary.
  *    You may call psa_reset_key_attributes(), although this is optional
  *    with the workflow presented here because the attributes currently
  *    defined in this specification do not require any additional resources
  *    beyond the structure itself.
  *
  * A typical sequence to query a key's attributes is as follows:
  * -# Call psa_get_key_attributes().
  * -# Call `psa_get_key_xxx` functions to retrieve the attribute(s) that
  *    you are interested in.
  * -# Call psa_reset_key_attributes() to free any resources that may be
  *    used by the attribute structure.
  *
  * Once a key has been created, it is impossible to change its attributes.
  */
 typedef struct psa_client_key_attributes_s psa_key_attributes_t;
 
 /**@}*/
 
 /** \defgroup derivation Key derivation
  * @{
  */
 
 /** \brief Encoding of the step of a key derivation. */
 typedef uint16_t psa_key_derivation_step_t;
 
 /**@}*/
 
 #endif /* PSA_CRYPTO_TYPES_H */
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