Update dhm.h
Minor documentation improvements:
*Standardized file brief description.
*Separated return statements.
*Reordered tags within documentation blocks so that params and returns are last in block.
*p_rng descriptions changed from "parameter" to "context".
*Suggest to specify issue for each return code, where multiple failure return codes are listed, or generalize.
*Minor improvements to parameter documentation proposed by eng.
diff --git a/include/mbedtls/dhm.h b/include/mbedtls/dhm.h
index 00fafd8..2829ffc 100644
--- a/include/mbedtls/dhm.h
+++ b/include/mbedtls/dhm.h
@@ -1,7 +1,12 @@
/**
* \file dhm.h
*
- * \brief Diffie-Hellman-Merkle key exchange.
+ * \brief This file contains DHM definitions and functions.
+ *
+ * Diffie-Hellman-Merkle (DHM) key exchange is defined in
+ * <em>RFC-2631: Diffie-Hellman Key Agreement Method</em> and
+ * <em>Public-Key Cryptography Standards (PKCS) #3: Diffie
+ * Hellman Key Agreement Standard</em>.
*
* <em>RFC-3526: More Modular Exponential (MODP) Diffie-Hellman groups for
* Internet Key Exchange (IKE)</em> defines a number of standardized
@@ -125,8 +130,8 @@
* failures.
* \param end The end of the input buffer.
*
- * \return \c 0 on success, or an \c MBEDTLS_ERR_DHM_XXX error code
- * on failure.
+ * \return \c 0 on success.
+ * \return An \c MBEDTLS_ERR_DHM_XXX error code on failure.
*/
int mbedtls_dhm_read_params( mbedtls_dhm_context *ctx,
unsigned char **p,
@@ -136,13 +141,6 @@
* \brief This function sets up and writes the ServerKeyExchange
* parameters.
*
- * \param ctx The DHM context.
- * \param x_size The private value size in Bytes.
- * \param olen The number of characters written.
- * \param output The destination buffer.
- * \param f_rng The RNG function.
- * \param p_rng The RNG parameter.
- *
* \note The destination buffer must be large enough to hold
* the reduced binary presentation of the modulus, the generator
* and the public key, each wrapped with a 2-byte length field.
@@ -155,8 +153,15 @@
* mbedtls_dhm_set_group() below in conjunction with
* mbedtls_mpi_read_binary() and mbedtls_mpi_read_string().
*
- * \return \c 0 on success, or an \c MBEDTLS_ERR_DHM_XXX error code
- * on failure.
+ * \param ctx The DHM context.
+ * \param x_size The private key size in Bytes.
+ * \param olen The number of characters written.
+ * \param output The destination buffer.
+ * \param f_rng The RNG function.
+ * \param p_rng The RNG context.
+ *
+ * \return \c 0 on success.
+ * \return An \c MBEDTLS_ERR_DHM_XXX error code on failure.
*/
int mbedtls_dhm_make_params( mbedtls_dhm_context *ctx, int x_size,
unsigned char *output, size_t *olen,
@@ -164,54 +169,54 @@
void *p_rng );
/**
- * \brief Set prime modulus and generator
+ * \brief This function sets the prime modulus and generator.
+ *
+ * \note This function can be used to set \p P, \p G
+ * in preparation for mbedtls_dhm_make_params().
*
* \param ctx The DHM context.
- * \param P The MPI holding DHM prime modulus.
- * \param G The MPI holding DHM generator.
+ * \param P The MPI holding the DHM prime modulus.
+ * \param G The MPI holding the DHM generator.
*
- * \note This function can be used to set P, G
- * in preparation for \c mbedtls_dhm_make_params.
- *
- * \return \c 0 if successful, or an \c MBEDTLS_ERR_DHM_XXX error code
- * on failure.
+ * \return \c 0 if successful.
+ * \return An \c MBEDTLS_ERR_DHM_XXX error code on failure.
*/
int mbedtls_dhm_set_group( mbedtls_dhm_context *ctx,
const mbedtls_mpi *P,
const mbedtls_mpi *G );
/**
- * \brief This function imports the public value G^Y of the peer.
+ * \brief This function imports the G^Y public value of the peer.
*
* \param ctx The DHM context.
- * \param input The input buffer.
+ * \param input The input buffer containing the G^Y value of the peer.
* \param ilen The size of the input buffer.
*
- * \return \c 0 on success, or an \c MBEDTLS_ERR_DHM_XXX error code
- * on failure.
+ * \return \c 0 on success.
+ * \return An \c MBEDTLS_ERR_DHM_XXX error code on failure.
*/
int mbedtls_dhm_read_public( mbedtls_dhm_context *ctx,
const unsigned char *input, size_t ilen );
/**
- * \brief This function creates its own private value \c X and
+ * \brief This function creates its own \c X private key and
* exports \c G^X.
*
+ * \note The destination buffer is always fully written
+ * so as to contain a big-endian representation of G^X mod P.
+ * If it is larger than ctx->len, it is padded accordingly
+ * with zero-bytes at the beginning.
+ *
* \param ctx The DHM context.
- * \param x_size The private value size in Bytes.
+ * \param x_size The private key size in Bytes.
* \param output The destination buffer.
* \param olen The length of the destination buffer. Must be at least
- equal to ctx->len (the size of \c P).
+ * equal to ctx->len (the size of \c P).
* \param f_rng The RNG function.
- * \param p_rng The RNG parameter.
+ * \param p_rng The RNG context.
*
- * \note The destination buffer will always be fully written
- * so as to contain a big-endian presentation of G^X mod P.
- * If it is larger than ctx->len, it will accordingly be
- * padded with zero-bytes in the beginning.
- *
- * \return \c 0 on success, or an \c MBEDTLS_ERR_DHM_XXX error code
- * on failure.
+ * \return \c 0 on success.
+ * \return An \c MBEDTLS_ERR_DHM_XXX error code on failure.
*/
int mbedtls_dhm_make_public( mbedtls_dhm_context *ctx, int x_size,
unsigned char *output, size_t olen,
@@ -222,22 +227,22 @@
* \brief This function derives and exports the shared secret
* \c (G^Y)^X mod \c P.
*
+ * \note If \p f_rng is not NULL, it is used to blind the input as
+ * a countermeasure against timing attacks. Blinding is used
+ * only if our private key \c X is re-used, and not used
+ * otherwise. We recommend always passing a non-NULL
+ * \p f_rng argument.
+ *
* \param ctx The DHM context.
* \param output The destination buffer.
* \param output_size The size of the destination buffer. Must be at least
- * the size of ctx->len.
+ * the size of ctx->len (the size of \c P).
* \param olen On exit, holds the actual number of Bytes written.
* \param f_rng The RNG function, for blinding purposes.
- * \param p_rng The RNG parameter.
+ * \param p_rng The RNG context.
*
- * \return \c 0 on success, or an \c MBEDTLS_ERR_DHM_XXX error code
- * on failure.
- *
- * \note If non-NULL, \p f_rng is used to blind the input as
- * a countermeasure against timing attacks. Blinding is used
- * only if our secret value \p X is re-used and omitted
- * otherwise. Therefore, we recommend always passing a
- * non-NULL \p f_rng argument.
+ * \return \c 0 on success.
+ * \return An \c MBEDTLS_ERR_DHM_XXX error code on failure.
*/
int mbedtls_dhm_calc_secret( mbedtls_dhm_context *ctx,
unsigned char *output, size_t output_size, size_t *olen,
@@ -245,7 +250,7 @@
void *p_rng );
/**
- * \brief This function frees and clears the components of a DHM key.
+ * \brief This function frees and clears the components of a DHM context.
*
* \param ctx The DHM context to free and clear.
*/
@@ -261,8 +266,8 @@
* \param dhminlen The size of the buffer, including the terminating null
* Byte for PEM data.
*
- * \return \c 0 on success, or a specific DHM or PEM error code
- * on failure.
+ * \return \c 0 on success.
+ * \return A specific DHM or PEM error code on failure.
*/
int mbedtls_dhm_parse_dhm( mbedtls_dhm_context *dhm, const unsigned char *dhmin,
size_t dhminlen );
@@ -275,8 +280,8 @@
* \param dhm The DHM context to load the parameters to.
* \param path The filename to read the DHM parameters from.
*
- * \return \c 0 on success, or a specific DHM or PEM error code
- * on failure.
+ * \return \c 0 on success.
+ * \return A specific DHM or PEM error code on failure.
*/
int mbedtls_dhm_parse_dhmfile( mbedtls_dhm_context *dhm, const char *path );
#endif /* MBEDTLS_FS_IO */
@@ -297,7 +302,8 @@
/**
* \brief The DMH checkup routine.
*
- * \return \c 0 on success, or \c 1 on failure.
+ * \return \c 0 on success.
+ * \return \c 1 on failure.
*/
int mbedtls_dhm_self_test( int verbose );