From 6669918d67764eb367ff2bcf30bb3cc25468e051 Mon Sep 17 00:00:00 2001 From: Janos Follath Date: Thu, 8 Dec 2016 16:15:51 +0000 Subject: [PATCH] Apply feedback to ECP internal interface documentation --- include/mbedtls/ecp_internal.h | 72 +++++++++++++++++++++------------- 1 file changed, 45 insertions(+), 27 deletions(-) diff --git a/include/mbedtls/ecp_internal.h b/include/mbedtls/ecp_internal.h index ff7d1cb60..2991e26dd 100644 --- a/include/mbedtls/ecp_internal.h +++ b/include/mbedtls/ecp_internal.h @@ -25,12 +25,8 @@ /* * References: * - * SEC1 http://www.secg.org/index.php?action=secg,docs_secg - * GECC = Guide to Elliptic Curve Cryptography - Hankerson, Menezes, Vanstone - * FIPS 186-3 http://csrc.nist.gov/publications/fips/fips186-3/fips_186-3.pdf - * RFC 4492 for the related TLS structures and constants - * - * [Curve25519] http://cr.yp.to/ecdh/curve25519-20060209.pdf + * [1] BERNSTEIN, Daniel J. Curve25519: new Diffie-Hellman speed records. + * * * [2] CORON, Jean-S'ebastien. Resistance against differential power analysis * for elliptic curve cryptosystems. In : Cryptographic Hardware and @@ -41,6 +37,24 @@ * render ECC resistant against Side Channel Attacks. IACR Cryptology * ePrint Archive, 2004, vol. 2004, p. 342. * + * + * [4] Certicom Research. SEC 2: Recommended Elliptic Curve Domain Parameters. + * + * + * [5] HANKERSON, Darrel, MENEZES, Alfred J., VANSTONE, Scott. Guide to Elliptic + * Curve Cryptography. + * + * [6] Digital Signature Standard (DSS), FIPS 186-4. + * + * + * [7] Elliptic Curve Cryptography (ECC) Cipher Suites for Transport Layer + * Security (TLS), RFC 4492. + * + * + * [8] + * + * [9] COHEN, Henri. A Course in Computational Algebraic Number Theory. + * Springer Science & Business Media, 1 Aug 2000 */ #ifndef MBEDTLS_ECP_INTERNAL_H @@ -49,22 +63,27 @@ #if defined(MBEDTLS_ECP_INTERNAL_ALT) /** - * \brief Tell if the cryptographic hardware can handle the group. + * \brief Indicate if the Elliptic Curve Point module extension can + * handle the group. * - * \param grp The pointer to the group. + * \param grp The pointer to the elliptic curve group that will be the + * basis of the cryptographic computations. * * \return Non-zero if successful. */ unsigned char mbedtls_internal_ecp_grp_capable( const mbedtls_ecp_group *grp ); /** - * \brief Initialise the crypto hardware accelerator. + * \brief Initialise the Elliptic Curve Point module extension. * * If mbedtls_internal_ecp_grp_capable returns true for a * group, this function has to be able to initialise the - * hardware for it. + * module for it. * - * \param grp The pointer to the group the hardware needs to be + * This module can be a driver to a crypto hardware + * accelerator, for which this could be an initialise function. + * + * \param grp The pointer to the group the module needs to be * initialised for. * * \return 0 if successful. @@ -72,10 +91,10 @@ unsigned char mbedtls_internal_ecp_grp_capable( const mbedtls_ecp_group *grp ); int mbedtls_internal_ecp_init( const mbedtls_ecp_group *grp ); /** - * \brief Reset the crypto hardware accelerator to an uninitialised - * state. + * \brief Frees and deallocates the Elliptic Curve Point module + * extension. * - * \param grp The pointer to the group the hardware was initialised for. + * \param grp The pointer to the group the module was initialised for. */ void mbedtls_internal_ecp_free( const mbedtls_ecp_group *grp ); @@ -86,9 +105,6 @@ void mbedtls_internal_ecp_free( const mbedtls_ecp_group *grp ); * \brief Randomize jacobian coordinates: * (X, Y, Z) -> (l^2 X, l^3 Y, l Z) for random l. * - * This is sort of the reverse operation of - * ecp_normalize_jac(). - * * \param grp Pointer to the group representing the curve. * * \param pt The point on the curve to be randomised, given with Jacobian @@ -112,6 +128,9 @@ int mbedtls_internal_ecp_randomize_jac( const mbedtls_ecp_group *grp, * The coordinates of Q must be normalized (= affine), * but those of P don't need to. R is not normalized. * + * This function is used only as a subrutine of + * ecp_mul_comb(). + * * Special cases: (1) P or Q is zero, (2) R is zero, * (3) P == Q. * None of these cases can happen as intermediate step in @@ -127,7 +146,7 @@ int mbedtls_internal_ecp_randomize_jac( const mbedtls_ecp_group *grp, * We accept Q->Z being unset (saving memory in tables) as * meaning 1. * - * Cost in field operations if done by GECC 3.22: + * Cost in field operations if done by [5] 3.22: * 1A := 8M + 3S * * \param grp Pointer to the group representing the curve. @@ -153,11 +172,9 @@ int mbedtls_internal_ecp_add_mixed( const mbedtls_ecp_group *grp, * Cost: 1D := 3M + 4S (A == 0) * 4M + 4S (A == -3) * 3M + 6S + 1a otherwise - * when the implementation is based on - * http://www.hyperelliptic.org/EFD/g1p/ - * auto-shortw-jacobian.html#doubling-dbl-1998-cmo-2 - * and standard optimizations are applied when curve parameter - * A is one of { 0, -3 }. + * when the implementation is based on the "dbl-1998-cmo-2" + * doubling formulas in [8] and standard optimizations are + * applied when curve parameter A is one of { 0, -3 }. * * \param grp Pointer to the group representing the curve. * @@ -180,8 +197,10 @@ int mbedtls_internal_ecp_double_jac( const mbedtls_ecp_group *grp, * Using Montgomery's trick to perform only one inversion mod P * the cost is: * 1N(t) := 1I + (6t - 3)M + 1S - * (See for example Cohen's "A Course in Computational - * Algebraic Number Theory", Algorithm 10.3.4.) + * (See for example Algorithm 10.3.4. in [9]) + * + * This function is used only as a subrutine of + * ecp_mul_comb(). * * Warning: fails (returning an error) if one of the points is * zero! @@ -204,7 +223,7 @@ int mbedtls_internal_ecp_normalize_jac_many( const mbedtls_ecp_group *grp, /** * \brief Normalize jacobian coordinates so that Z == 0 || Z == 1. * - * Cost in field operations if done by GECC 3.2.1: + * Cost in field operations if done by [5] 3.2.1: * 1N := 1I + 3M + 1S * * \param grp Pointer to the group representing the curve. @@ -232,7 +251,6 @@ int mbedtls_internal_ecp_double_add_mxz( const mbedtls_ecp_group *grp, /** * \brief Randomize projective x/z coordinates: * (X, Z) -> (l X, l Z) for random l - * This is sort of the reverse operation of ecp_normalize_mxz(). * * \param grp pointer to the group representing the curve *