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Define and implement new key export API for Mbed TLS 3.0

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Signed-off-by: Hanno Becker <hanno.becker@arm.com>
This commit is contained in:
Hanno Becker 2021-05-24 10:27:39 +01:00 committed by Dave Rodgman
parent 2d6e6f8fec
commit 457d61602f
2 changed files with 79 additions and 87 deletions
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151
include/mbedtls/ssl.h
View File

@ -458,18 +458,6 @@ typedef enum
}
mbedtls_ssl_states;
/*
* The tls_prf function types.
*/
typedef enum
{
MBEDTLS_SSL_TLS_PRF_NONE,
MBEDTLS_SSL_TLS_PRF_TLS1,
MBEDTLS_SSL_TLS_PRF_SHA384,
MBEDTLS_SSL_TLS_PRF_SHA256
}
mbedtls_tls_prf_types;
/**
* \brief Callback type: send data on the network.
*
@ -967,6 +955,58 @@ struct mbedtls_ssl_session
#endif
};
/*
* Identifiers for PRFs used in various versions of TLS.
*/
typedef enum
{
MBEDTLS_SSL_TLS_PRF_NONE,
MBEDTLS_SSL_TLS_PRF_TLS1,
MBEDTLS_SSL_TLS_PRF_SHA384,
MBEDTLS_SSL_TLS_PRF_SHA256,
MBEDTLS_SSL_HKDF_EXPAND_SHA384,
MBEDTLS_SSL_HKDF_EXPAND_SHA256
}
mbedtls_tls_prf_types;
#if defined(MBEDTLS_SSL_EXPORT_KEYS)
typedef enum
{
MBEDTLS_SSL_KEY_EXPORT_TLS12_MASTER_SECRET = 0,
#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
MBEDTLS_SSL_KEY_EXPORT_TLS13_CLIENT_EARLY_SECRET,
MBEDTLS_SSL_KEY_EXPORT_TLS13_EARLY_EXPORTER_SECRET,
MBEDTLS_SSL_KEY_EXPORT_TLS13_CLIENT_HANDSHAKE_TRAFFIC_SECRET,
MBEDTLS_SSL_KEY_EXPORT_TLS13_SERVER_HANDSHAKE_TRAFFIC_SECRET,
MBEDTLS_SSL_KEY_EXPORT_TLS13_CLIENT_APPLICATION_TRAFFIC_SECRET,
MBEDTLS_SSL_KEY_EXPORT_TLS13_SERVER_APPLICATION_TRAFFIC_SECRET,
#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
} mbedtls_ssl_key_export_type;
/**
* \brief Callback type: Export key alongside random values for
* session identification, and PRF for
* implementation of TLS key exporters.
*
* \param p_expkey Context for the callback.
* \param type The type of the key that is being exported.
* \param client_random The client random bytes.
* \param server_random The server random bytes.
* \param tls_prf_type The identifier for the PRF used in the handshake
* to which the key belongs.
*
* \return \c 0 if successful.
* \return A negative error code on failure.
*/
typedef int mbedtls_ssl_export_keys_t( void *p_expkey,
mbedtls_ssl_key_export_type type,
const unsigned char *secret,
size_t secret_len,
const unsigned char client_random[32],
const unsigned char server_random[32],
mbedtls_tls_prf_types tls_prf_type );
#endif /* MBEDTLS_SSL_EXPORT_KEYS */
/**
* SSL/TLS configuration to be shared between mbedtls_ssl_context structures.
*/
@ -1033,12 +1073,8 @@ struct mbedtls_ssl_config
#endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_SRV_C */
#if defined(MBEDTLS_SSL_EXPORT_KEYS)
/** Callback to export key block, master secret,
* tls_prf and random bytes. Should replace f_export_keys */
int (*MBEDTLS_PRIVATE(f_export_keys))( void *, const unsigned char *,
const unsigned char *, size_t, size_t, size_t,
const unsigned char[32], const unsigned char[32],
mbedtls_tls_prf_types );
/** Callback to export key block and master secret */
mbedtls_ssl_export_keys_t *MBEDTLS_PRIVATE(f_export_keys);
void *MBEDTLS_PRIVATE(p_export_keys); /*!< context for key export callback */
#endif
@ -1915,43 +1951,6 @@ typedef int mbedtls_ssl_ticket_write_t( void *p_ticket,
size_t *tlen,
uint32_t *lifetime );
#if defined(MBEDTLS_SSL_EXPORT_KEYS)
/**
* \brief Callback type: Export key block, master secret,
* handshake randbytes and the tls_prf function
* used to derive keys.
*
* \note This is required for certain uses of TLS, e.g. EAP-TLS
* (RFC 5216) and Thread. The key pointers are ephemeral and
* therefore must not be stored. The master secret and keys
* should not be used directly except as an input to a key
* derivation function.
*
* \param p_expkey Context for the callback.
* \param ms Pointer to master secret (fixed length: 48 bytes).
* \param kb Pointer to key block, see RFC 5246 section 6.3.
* (variable length: 2 * maclen + 2 * keylen + 2 * ivlen).
* \param maclen MAC length.
* \param keylen Key length.
* \param ivlen IV length.
* \param client_random The client random bytes.
* \param server_random The server random bytes.
* \param tls_prf_type The tls_prf enum type.
*
* \return 0 if successful, or
* a specific MBEDTLS_ERR_XXX code.
*/
typedef int mbedtls_ssl_export_keys_t( void *p_expkey,
const unsigned char *ms,
const unsigned char *kb,
size_t maclen,
size_t keylen,
size_t ivlen,
const unsigned char client_random[32],
const unsigned char server_random[32],
mbedtls_tls_prf_types tls_prf_type );
#endif /* MBEDTLS_SSL_EXPORT_KEYS */
/**
* \brief Callback type: parse and load session ticket
*
@ -2003,34 +2002,28 @@ void mbedtls_ssl_conf_session_tickets_cb( mbedtls_ssl_config *conf,
#if defined(MBEDTLS_SSL_EXPORT_KEYS)
/**
* \brief Configure key export callback.
* (Default: none.)
* \brief Configure a key export callback.
* (Default: none.)
*
* \note See \c mbedtls_ssl_export_keys_t.
* This API can be used for two purposes:
* - Debugging: Use this API to e.g. generate an NSSKeylog
* file and use it to inspect encrypted traffic in tools
* such as Wireshark.
* - Application-specific export: Use this API to implement
* key exporters, e.g. for EAP-TLS or DTLS-SRTP.
*
* \param conf SSL configuration context
* \param f_export_keys Callback for exporting keys
* \param p_export_keys Context for the callback
*
* \param conf The SSL configuration to which the export
* callback should be attached. All connections
* subsequently bound to this configuration will
* have their keys exported.
* \param f_export_keys The callback for the key export.
* \param p_export_keys The opaque context pointer to be passed to the
* callback \p f_export_keys.
*/
void mbedtls_ssl_conf_export_keys_cb( mbedtls_ssl_config *conf,
mbedtls_ssl_export_keys_t *f_export_keys,
void *p_export_keys );
/**
* \brief Configure extended key export callback.
* (Default: none.)
*
* \note See \c mbedtls_ssl_export_keys_t.
* \warning Exported key material must not be used for any purpose
* before the (D)TLS handshake is completed
*
* \param conf SSL configuration context
* \param f_export_keys Callback for exporting keys
* \param p_export_keys Context for the callback
*/
void mbedtls_ssl_conf_export_keys_cb( mbedtls_ssl_config *conf,
mbedtls_ssl_export_keys_t *f_export_keys,
void *p_export_keys );
mbedtls_ssl_export_keys_t *f_export_keys,
void *p_export_keys );
#endif /* MBEDTLS_SSL_EXPORT_KEYS */
#if defined(MBEDTLS_SSL_ASYNC_PRIVATE)

15
library/ssl_tls.c
View File

@ -989,12 +989,11 @@ static int ssl_populate_transform( mbedtls_ssl_transform *transform,
if( ssl->conf->f_export_keys != NULL )
{
ssl->conf->f_export_keys( ssl->conf->p_export_keys,
master, keyblk,
mac_key_len, keylen,
iv_copy_len,
randbytes + 32,
randbytes,
tls_prf_get_type( tls_prf ) );
MBEDTLS_SSL_KEY_EXPORT_TLS12_MASTER_SECRET,
master, 48,
randbytes + 32,
randbytes,
tls_prf_get_type( tls_prf ) );
}
#endif
@ -4186,8 +4185,8 @@ void mbedtls_ssl_conf_session_tickets_cb( mbedtls_ssl_config *conf,
#if defined(MBEDTLS_SSL_EXPORT_KEYS)
void mbedtls_ssl_conf_export_keys_cb( mbedtls_ssl_config *conf,
mbedtls_ssl_export_keys_t *f_export_keys,
void *p_export_keys )
mbedtls_ssl_export_keys_t *f_export_keys,
void *p_export_keys )
{
conf->f_export_keys = f_export_keys;
conf->p_export_keys = p_export_keys;