Document parameter preconditions in ECH module

This commit is contained in:
Hanno Becker 2018-12-17 18:10:43 +00:00
parent af0c6cb9e0
commit e77ef2ad33

View file

@ -149,11 +149,16 @@ mbedtls_ecdh_context;
* *
* \see ecp.h * \see ecp.h
* *
* \param grp The ECP group. * \param grp The ECP group to use. This must be initialized and have
* domain parameters loaded, for example through
* mbedtls_ecp_load() or mbedtls_ecp_tls_read_group().
* \param d The destination MPI (private key). * \param d The destination MPI (private key).
* This must be initialized.
* \param Q The destination point (public key). * \param Q The destination point (public key).
* \param f_rng The RNG function. * This must be initialized.
* \param p_rng The RNG context. * \param f_rng The RNG function to use. This must not be \c NULL.
* \param p_rng The RNG context to be passed to \p f_rng. This may be
* \c NULL in case \p f_rng doesn't need a context argument.
* *
* \return \c 0 on success. * \return \c 0 on success.
* \return Another \c MBEDTLS_ERR_ECP_XXX or * \return Another \c MBEDTLS_ERR_ECP_XXX or
@ -176,12 +181,22 @@ int mbedtls_ecdh_gen_public( mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp
* countermeasures against side-channel attacks. * countermeasures against side-channel attacks.
* For more information, see mbedtls_ecp_mul(). * For more information, see mbedtls_ecp_mul().
* *
* \param grp The ECP group. * \param grp The ECP group to use. This must be initialized and have
* domain parameters loaded, for example through
* mbedtls_ecp_load() or mbedtls_ecp_tls_read_group().
* \param z The destination MPI (shared secret). * \param z The destination MPI (shared secret).
* This must be initialized.
* \param Q The public key from another party. * \param Q The public key from another party.
* This must be initialized.
* \param d Our secret exponent (private key). * \param d Our secret exponent (private key).
* \param f_rng The RNG function. * This must be initialized.
* \param p_rng The RNG context. * \param f_rng The RNG function. This may be \c NULL if randomization
* of intermediate results during the ECP computations is
* not needed (discouraged). See the documentation of
* mbedtls_ecp_mul() for more.
* \param p_rng The RNG context to be passed to \p f_rng. This may be
* \c NULL if \p f_rng is \c NULL or doesn't need a
* context argument.
* *
* \return \c 0 on success. * \return \c 0 on success.
* \return Another \c MBEDTLS_ERR_ECP_XXX or * \return Another \c MBEDTLS_ERR_ECP_XXX or
@ -195,7 +210,7 @@ int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z,
/** /**
* \brief This function initializes an ECDH context. * \brief This function initializes an ECDH context.
* *
* \param ctx The ECDH context to initialize. * \param ctx The ECDH context to initialize. This must not be \c NULL.
*/ */
void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx ); void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx );
@ -210,39 +225,42 @@ void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx );
* This is the first function used by a TLS server for ECDHE * This is the first function used by a TLS server for ECDHE
* ciphersuites. * ciphersuites.
* *
* \param ctx The ECDH context to set up. * \param ctx The ECDH context to set up. This must be initialized.
* \param grp_id The group id of the group to set up the context for. * \param grp_id The group id of the group to set up the context for.
* *
* \return \c 0 on success. * \return \c 0 on success.
*/ */
int mbedtls_ecdh_setup( mbedtls_ecdh_context *ctx, mbedtls_ecp_group_id grp_id ); int mbedtls_ecdh_setup( mbedtls_ecdh_context *ctx,
mbedtls_ecp_group_id grp_id );
/** /**
* \brief This function frees a context. * \brief This function frees a context.
* *
* \param ctx The context to free. * \param ctx The context to free. This may be \c NULL, in which
* case this function does nothing. If it is not \c NULL,
* it must point to an initialized ECDH context.
*/ */
void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx ); void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx );
/** /**
* \brief This function generates a public key and a TLS * \brief This function generates an EC key pair and exports its
* ServerKeyExchange payload. * in the format used in a TLS ServerKeyExchange handshake
* message.
* *
* This is the second function used by a TLS server for ECDHE * This is the second function used by a TLS server for ECDHE
* ciphersuites. (It is called after mbedtls_ecdh_setup().) * ciphersuites. (It is called after mbedtls_ecdh_setup().)
* *
* \note This function assumes that the ECP group (grp) of the
* \p ctx context has already been properly set,
* for example, using mbedtls_ecp_group_load().
*
* \see ecp.h * \see ecp.h
* *
* \param ctx The ECDH context. * \param ctx The ECDH context to use. This must be initialized
* \param olen The number of characters written. * and bound to a group, for example via mbedtls_ecdh_setup().
* \param buf The destination buffer. * \param olen The address at which to store the number of Bytes written.
* \param blen The length of the destination buffer. * \param buf The destination buffer. This must be a writable buffer of
* \param f_rng The RNG function. * length \p blen Bytes.
* \param p_rng The RNG context. * \param blen The length of the destination buffer \p buf in Bytes.
* \param f_rng The RNG function to use. This must not be \c NULL.
* \param p_rng The RNG context to be passed to \p f_rng. This may be
* \c NULL in case \p f_rng doesn't need a context argument.
* *
* \return \c 0 on success. * \return \c 0 on success.
* \return #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of * \return #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
@ -255,24 +273,32 @@ int mbedtls_ecdh_make_params( mbedtls_ecdh_context *ctx, size_t *olen,
void *p_rng ); void *p_rng );
/** /**
* \brief This function parses and processes a TLS ServerKeyExhange * \brief This function parses the ECDHE parameters in a
* payload. * TLS ServerKeyExchange handshake message.
* *
* This is the first function used by a TLS client for ECDHE * \note In a TLS handshake, this is the how the client
* ciphersuites. * sets up its ECDHE context from the server's public
* ECDHE key material.
* *
* \see ecp.h * \see ecp.h
* *
* \param ctx The ECDH context. * \param ctx The ECDHE context to use. This must be initialized.
* \param buf The pointer to the start of the input buffer. * \param p On input, *p must be the start of the input buffer.
* \param end The address for one Byte past the end of the buffer. * On output, *p is updated to point to the end of the data
* that has been read. On success, this is the first byte
* past the end of the ServerKeyExchange parameters.
* On error, this is the point at which an error has been
* detected, which is usually not useful except to debug
* failures.
* \param end The end of the input buffer.
* *
* \return \c 0 on success. * \return \c 0 on success.
* \return An \c MBEDTLS_ERR_ECP_XXX error code on failure. * \return An \c MBEDTLS_ERR_ECP_XXX error code on failure.
* *
*/ */
int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx, int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx,
const unsigned char **buf, const unsigned char *end ); const unsigned char **buf,
const unsigned char *end );
/** /**
* \brief This function sets up an ECDH context from an EC key. * \brief This function sets up an ECDH context from an EC key.
@ -283,33 +309,40 @@ int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx,
* *
* \see ecp.h * \see ecp.h
* *
* \param ctx The ECDH context to set up. * \param ctx The ECDH context to set up. This must be initialized.
* \param key The EC key to use. * \param key The EC key to use. This must be initialized.
* \param side Defines the source of the key: 1: Our key, or * \param side Defines the source of the key. Possible values are:
* 0: The key of the peer. * - \c 1: The imported key is ours.
* - \c 0: The imported key is that of the peer.
* *
* \return \c 0 on success. * \return \c 0 on success.
* \return Another \c MBEDTLS_ERR_ECP_XXX error code on failure. * \return Another \c MBEDTLS_ERR_ECP_XXX error code on failure.
* *
*/ */
int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx, const mbedtls_ecp_keypair *key, int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx,
mbedtls_ecdh_side side ); const mbedtls_ecp_keypair *key,
mbedtls_ecdh_side side );
/** /**
* \brief This function generates a public key and a TLS * \brief This function generates a public key and exports it
* ClientKeyExchange payload. * as a TLS ClientKeyExchange payload.
* *
* This is the second function used by a TLS client for ECDH(E) * This is the second function used by a TLS client for ECDH(E)
* ciphersuites. * ciphersuites.
* *
* \see ecp.h * \see ecp.h
* *
* \param ctx The ECDH context. * \param ctx The ECDH context to use. This must be initialized
* \param olen The number of Bytes written. * and bound to a group, the latter usually by
* \param buf The destination buffer. * mbedtls_ecdh_read_params().
* \param blen The size of the destination buffer. * \param olen The address at which to store the number of Bytes written.
* \param f_rng The RNG function. * This must not be \c NULL.
* \param p_rng The RNG context. * \param buf The destination buffer. This must be a writable buffer
* of lsength \p blen Bytes.
* \param blen The size of the destination buffer \p buf in Bytes.
* \param f_rng The RNG function to use. This must not be \c NULL.
* \param p_rng The RNG context to be passed to \p f_rng. This may be
* \c NULL in case \p f_rng doesn't need a context argument.
* *
* \return \c 0 on success. * \return \c 0 on success.
* \return #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of * \return #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
@ -322,8 +355,8 @@ int mbedtls_ecdh_make_public( mbedtls_ecdh_context *ctx, size_t *olen,
void *p_rng ); void *p_rng );
/** /**
* \brief This function parses and processes a TLS ClientKeyExchange * \brief This function parses and processes the ECDHE payload of a
* payload. * TLS ClientKeyExchange message.
* *
* This is the third function used by a TLS server for ECDH(E) * This is the third function used by a TLS server for ECDH(E)
* ciphersuites. (It is called after mbedtls_ecdh_setup() and * ciphersuites. (It is called after mbedtls_ecdh_setup() and
@ -331,15 +364,17 @@ int mbedtls_ecdh_make_public( mbedtls_ecdh_context *ctx, size_t *olen,
* *
* \see ecp.h * \see ecp.h
* *
* \param ctx The ECDH context. * \param ctx The ECDH context to use. This must be initialized
* \param buf The start of the input buffer. * and bound to a group, for example via mbedtls_ecdh_setup().
* \param blen The length of the input buffer. * \param buf The pointer to the ClientKeyExchange payload. This must
* be a readable buffer of length \p blen Bytes.
* \param blen The length of the input buffer \p buf in Bytes.
* *
* \return \c 0 on success. * \return \c 0 on success.
* \return An \c MBEDTLS_ERR_ECP_XXX error code on failure. * \return An \c MBEDTLS_ERR_ECP_XXX error code on failure.
*/ */
int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx, int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx,
const unsigned char *buf, size_t blen ); const unsigned char *buf, size_t blen );
/** /**
* \brief This function derives and exports the shared secret. * \brief This function derives and exports the shared secret.
@ -352,13 +387,19 @@ int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx,
* For more information, see mbedtls_ecp_mul(). * For more information, see mbedtls_ecp_mul().
* *
* \see ecp.h * \see ecp.h
*
* \param ctx The ECDH context. * \param ctx The ECDH context to use. This must be initialized
* \param olen The number of Bytes written. * and have its own private key generated and the peer's
* \param buf The destination buffer. * public key imported.
* \param blen The length of the destination buffer. * \param olen The address at which to store the total number of
* \param f_rng The RNG function. * Bytes written on success. This must not be \c NULL.
* \param p_rng The RNG context. * \param buf The buffer to write the generated shared key to. This
* must be a writable buffer of size \p blen Bytes.
* \param blen The length of the destination buffer \p buf in Bytes.
* \param f_rng The RNG function, for blinding purposes. This may
* b \c NULL if blinding isn't needed.
* \param p_rng The RNG context. This may be \c NULL if \p f_rng
* doesn't need a context argument.
* *
* \return \c 0 on success. * \return \c 0 on success.
* \return #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of * \return #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
@ -381,7 +422,7 @@ int mbedtls_ecdh_calc_secret( mbedtls_ecdh_context *ctx, size_t *olen,
* computations once enabled, except by free-ing the context, * computations once enabled, except by free-ing the context,
* which cancels possible in-progress operations. * which cancels possible in-progress operations.
* *
* \param ctx The ECDH context. * \param ctx The ECDH context to use. This must be initialized.
*/ */
void mbedtls_ecdh_enable_restart( mbedtls_ecdh_context *ctx ); void mbedtls_ecdh_enable_restart( mbedtls_ecdh_context *ctx );
#endif /* MBEDTLS_ECP_RESTARTABLE */ #endif /* MBEDTLS_ECP_RESTARTABLE */