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Add generator API

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Add an API for byte generators: psa_crypto_generator_t,
PSA_CRYPTO_GENERATOR_INIT, psa_crypto_generator_init,
psa_get_generator_capacity, psa_generator_read,
psa_generator_import_key, psa_generator_abort.

This commit does not yet implement any generator algorithm, it only
provides the framework. This code may not compile with -Wunused.
This commit is contained in:
Gilles Peskine 2018-07-12 17:12:33 +02:00 committed by itayzafrir
parent 9aa369eafb
commit eab56e4159
3 changed files with 296 additions and 2 deletions
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177
include/psa/crypto.h
View file

@ -285,12 +285,18 @@ typedef int32_t psa_status_t;
* depend on the validity of the padding. */
#define PSA_ERROR_INVALID_PADDING ((psa_status_t)16)
/** The generator has insufficient capacity left.
*
* Once a function returns this error, attempts to read from the
* generator will always return this error. */
#define PSA_ERROR_INSUFFICIENT_CAPACITY ((psa_status_t)17)
/** An error occurred that does not correspond to any defined
* failure cause.
*
* Implementations may use this error code if none of the other standard
* error codes are applicable. */
#define PSA_ERROR_UNKNOWN_ERROR ((psa_status_t)17)
#define PSA_ERROR_UNKNOWN_ERROR ((psa_status_t)18)
/**
* \brief Library initialization.
@ -2440,6 +2446,175 @@ psa_status_t psa_asymmetric_decrypt(psa_key_slot_t key,
/**@}*/
/** \defgroup generation Generators
* @{
*/
/** The type of the state data structure for generators.
*
* Before calling any function on a generator, the application must
* initialize it by any of the following means:
* - Set the structure to all-bits-zero, for example:
* \code
* psa_crypto_generator_t generator;
* memset(&generator, 0, sizeof(generator));
* \endcode
* - Initialize the structure to logical zero values, for example:
* \code
* psa_crypto_generator_t generator = {0};
* \endcode
* - Initialize the structure to the initializer #PSA_CRYPTO_GENERATOR_INIT,
* for example:
* \code
* psa_crypto_generator_t generator = PSA_CRYPTO_GENERATOR_INIT;
* \endcode
* - Assign the result of the function psa_crypto_generator_init()
* to the structure, for example:
* \code
* psa_crypto_generator_t generator;
* generator = psa_crypto_generator_init();
* \endcode
*
* This is an implementation-defined \c struct. Applications should not
* make any assumptions about the content of this structure except
* as directed by the documentation of a specific implementation.
*/
typedef struct psa_crypto_generator_s psa_crypto_generator_t;
/** \def PSA_CRYPTO_GENERATOR_INIT
*
* This macro returns a suitable initializer for a generator object
* of type #psa_crypto_generator_t.
*/
#ifdef __DOXYGEN_ONLY__
/* This is an example definition for documentation purposes.
* Implementations should define a suitable value in `crypto_struct.h`.
*/
#define PSA_CRYPTO_GENERATOR_INIT {0}
#endif
/** Return an initial value for a generator object.
*/
static psa_crypto_generator_t psa_crypto_generator_init(void);
/** Retrieve the current capacity of a generator.
*
* The capacity of a generator is the maximum number of bytes that it can
* return. Reading *N* bytes from a generator reduces its capacity by *N*.
*
* \param[in] generator The generator to query.
* \param[out] capacity On success, the capacity of the generator.
*
* \retval PSA_SUCCESS
* \retval PSA_ERROR_BAD_STATE
* \retval PSA_ERROR_COMMUNICATION_FAILURE
*/
psa_status_t psa_get_generator_capacity(const psa_crypto_generator_t *generator,
size_t *capacity);
/** Read some data from a generator.
*
* This function reads and returns a sequence of bytes from a generator.
* The data that is read is discarded from the generator. The generator's
* capacity is decreased by the number of bytes read.
*
* \param[in,out] generator The generator object to read from.
* \param[out] output Buffer where the generator output will be
* written.
* \param output_length Number of bytes to output.
*
* \retval PSA_SUCCESS
* \retval PSA_ERROR_INSUFFICIENT_CAPACITY
* There were fewer than \p output_length bytes
* in the generator. Note that in this case, no
* output is written to the output buffer.
* The generator's capacity is set to 0, thus
* subsequent calls to this function will not
* succeed, even with a smaller output buffer.
* \retval PSA_ERROR_BAD_STATE
* \retval PSA_ERROR_INSUFFICIENT_MEMORY
* \retval PSA_ERROR_COMMUNICATION_FAILURE
* \retval PSA_ERROR_HARDWARE_FAILURE
* \retval PSA_ERROR_TAMPERING_DETECTED
*/
psa_status_t psa_generator_read(psa_crypto_generator_t *generator,
uint8_t *output,
size_t output_length);
/** Create a symmetric key from data read from a generator.
*
* This function reads a sequence of bytes from a generator and imports
* these bytes as a key.
* The data that is read is discarded from the generator. The generator's
* capacity is decreased by the number of bytes read.
*
* This function is equivalent to calling #psa_generator_read and
* passing the resulting output to #psa_import_key, but
* if the implementation provides an isolation boundary then
* the key material is not exposed outside the isolation boundary.
*
* \param key Slot where the key will be stored. This must be a
* valid slot for a key of the chosen type. It must
* be unoccupied.
* \param type Key type (a \c PSA_KEY_TYPE_XXX value).
* This must be a symmetric key type.
* \param bits Key size in bits.
* \param[in,out] generator The generator object to read from.
*
* \retval PSA_SUCCESS
* Success.
* \retval PSA_ERROR_INSUFFICIENT_CAPACITY
* There were fewer than \p output_length bytes
* in the generator. Note that in this case, no
* output is written to the output buffer.
* The generator's capacity is set to 0, thus
* subsequent calls to this function will not
* succeed, even with a smaller output buffer.
* \retval PSA_ERROR_NOT_SUPPORTED
* The key type or key size is not supported, either by the
* implementation in general or in this particular slot.
* \retval PSA_ERROR_BAD_STATE
* \retval PSA_ERROR_INVALID_ARGUMENT
* The key slot is invalid.
* \retval PSA_ERROR_OCCUPIED_SLOT
* There is already a key in the specified slot.
* \retval PSA_ERROR_INSUFFICIENT_MEMORY
* \retval PSA_ERROR_INSUFFICIENT_STORAGE
* \retval PSA_ERROR_COMMUNICATION_FAILURE
* \retval PSA_ERROR_HARDWARE_FAILURE
* \retval PSA_ERROR_TAMPERING_DETECTED
*/
psa_status_t psa_generator_import_key(psa_key_slot_t key,
psa_key_type_t type,
size_t bits,
psa_crypto_generator_t *generator);
/** Abort a generator.
*
* Once a generator has been aborted, its capacity is zero.
* Aborting a generator frees all associated resources except for the
* \c generator structure itself.
*
* This function may be called at any time as long as the generator
* object has been initialized to #PSA_CRYPTO_GENERATOR_INIT, to
* psa_crypto_generator_init() or a zero value. In particular, it is valid
* to call psa_generator_abort() twice, or to call psa_generator_abort()
* on a generator that has not been set up.
*
* Once aborted, the generator object may be called.
*
* \param[in,out] generator The generator to abort.
*
* \retval PSA_SUCCESS
* \retval PSA_ERROR_BAD_STATE
* \retval PSA_ERROR_COMMUNICATION_FAILURE
* \retval PSA_ERROR_HARDWARE_FAILURE
* \retval PSA_ERROR_TAMPERING_DETECTED
*/
psa_status_t psa_generator_abort(psa_crypto_generator_t *generator);
/**@}*/
/** \defgroup generation Key generation
* @{
*/

21
include/psa/crypto_struct.h
View file

@ -130,6 +130,27 @@ struct psa_cipher_operation_s
} ctx;
};
struct psa_crypto_generator_s
{
psa_algorithm_t alg;
size_t capacity;
union
{
struct
{
uint8_t *data;
size_t size;
} buffer;
} ctx;
};
#define PSA_CRYPTO_GENERATOR_INIT {0, 0, {{0, 0}}}
static inline struct psa_crypto_generator_s psa_crypto_generator_init( void )
{
const struct psa_crypto_generator_s v = PSA_CRYPTO_GENERATOR_INIT;
return( v );
}
struct psa_key_policy_s
{
psa_key_usage_t usage;

100
library/psa_crypto.c
View file

@ -2988,7 +2988,105 @@ psa_status_t psa_aead_decrypt( psa_key_slot_t key,
/****************************************************************/
/* Key generation */
/* Generators */
/****************************************************************/
psa_status_t psa_generator_abort( psa_crypto_generator_t *generator )
{
psa_status_t status = PSA_SUCCESS;
if( generator->alg == 0 )
{
/* The object has (apparently) been initialized but it is not
* in use. It's ok to call abort on such an object, and there's
* nothing to do. */
}
else
{
status = PSA_ERROR_BAD_STATE;
}
memset( generator, 0, sizeof( *generator ) );
return( status );
}
psa_status_t psa_get_generator_capacity(const psa_crypto_generator_t *generator,
size_t *capacity)
{
*capacity = generator->capacity;
return( PSA_SUCCESS );
}
psa_status_t psa_generator_read( psa_crypto_generator_t *generator,
uint8_t *output,
size_t output_length )
{
psa_status_t status;
if( output_length > generator->capacity )
{
generator->capacity = 0;
/* Go through the error path to wipe all confidential data now
* that the generator object is useless. */
status = PSA_ERROR_INSUFFICIENT_CAPACITY;
goto exit;
}
if( output_length == 0 &&
generator->capacity == 0 && generator->alg == 0 )
{
/* Edge case: this is a blank or finished generator, and 0
* bytes were requested. The right error in this case could
* be either INSUFFICIENT_CAPACITY or BAD_STATE. Return
* INSUFFICIENT_CAPACITY, which is right for a finished
* generator, for consistency with the case when
* output_length > 0. */
return( PSA_ERROR_INSUFFICIENT_CAPACITY );
}
generator->capacity -= output_length;
{
return( PSA_ERROR_BAD_STATE );
}
exit:
if( status != PSA_SUCCESS )
{
psa_generator_abort( generator );
memset( output, '!', output_length );
}
return( status );
}
psa_status_t psa_generator_import_key( psa_key_slot_t key,
psa_key_type_t type,
size_t bits,
psa_crypto_generator_t *generator )
{
uint8_t *data = NULL;
size_t bytes = PSA_BITS_TO_BYTES( bits );
psa_status_t status;
if( ! key_type_is_raw_bytes( type ) )
return( PSA_ERROR_INVALID_ARGUMENT );
if( bits % 8 != 0 )
return( PSA_ERROR_INVALID_ARGUMENT );
data = mbedtls_calloc( 1, bytes );
if( data == NULL )
return( PSA_ERROR_INSUFFICIENT_MEMORY );
status = psa_generator_read( generator, data, bytes );
if( status != PSA_SUCCESS )
goto exit;
status = psa_import_key( key, type, data, bytes );
exit:
mbedtls_free( data );
return( status );
}
/****************************************************************/
/* Random generation */
/****************************************************************/
psa_status_t psa_generate_random( uint8_t *output,