ecmult_gen_impl.h File Reference

#include "scalar.h"
#include "group.h"
#include "ecmult_gen.h"
#include "hash_impl.h"

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Functions
static void	secp256k1_ecmult_gen_context_init (secp256k1_ecmult_gen_context *ctx)
static void	secp256k1_ecmult_gen_context_build (secp256k1_ecmult_gen_context *ctx, const secp256k1_callback *cb)
static int	secp256k1_ecmult_gen_context_is_built (const secp256k1_ecmult_gen_context *ctx)
static void	secp256k1_ecmult_gen_context_clone (secp256k1_ecmult_gen_context *dst, const secp256k1_ecmult_gen_context *src, const secp256k1_callback *cb)
static void	secp256k1_ecmult_gen_context_clear (secp256k1_ecmult_gen_context *ctx)
static void	secp256k1_ecmult_gen (const secp256k1_ecmult_gen_context *ctx, secp256k1_gej *r, const secp256k1_scalar *gn)
static void	secp256k1_ecmult_gen_blind (secp256k1_ecmult_gen_context *ctx, const unsigned char *seed32)

Function Documentation

secp256k1_ecmult_gen()

static void secp256k1_ecmult_gen ( const secp256k1_ecmult_gen_context *  ctx, secp256k1_gej *  r, const secp256k1_scalar *  gn  )

static

This uses a conditional move to avoid any secret data in array indexes. Any use of secret indexes has been demonstrated to result in timing sidechannels, even when the cache-line access patterns are uniform. See also: "A word of warning", CHES 2013 Rump Session, by Daniel J. Bernstein and Peter Schwabe (https://cryptojedi.org/peter/data/chesrump-20130822.pdf) and "Cache Attacks and Countermeasures: the Case of AES", RSA 2006, by Dag Arne Osvik, Adi Shamir, and Eran Tromer (http://www.tau.ac.il/~tromer/papers/cache.pdf)

Definition at line 124 of file ecmult_gen_impl.h.

References immer::detail::rbts::bits, ctx, secp256k1_ge::infinity, secp256k1_ge_clear(), secp256k1_ge_from_storage(), secp256k1_ge_storage_cmov(), secp256k1_gej_add_ge(), secp256k1_scalar_add(), secp256k1_scalar_clear(), and secp256k1_scalar_get_bits().

Referenced by secp256k1_ecmult_gen_blind().

secp256k1_ecmult_gen_blind()

static void secp256k1_ecmult_gen_blind ( secp256k1_ecmult_gen_context *  ctx, const unsigned char *  seed32  )

static

Using a CSPRNG allows a failure free interface, avoids needing large amounts of random data, and guards against weak or adversarial seeds. This is a simpler and safer interface than asking the caller for blinding values directly and expecting them to retry on failure.

Definition at line 159 of file ecmult_gen_impl.h.

References ctx, memcpy(), secp256k1_ecmult_gen(), secp256k1_fe_clear(), secp256k1_fe_is_zero(), secp256k1_fe_set_b32(), secp256k1_ge_const_g, secp256k1_gej_clear(), secp256k1_gej_neg(), secp256k1_gej_rescale(), secp256k1_gej_set_ge(), secp256k1_rfc6979_hmac_sha256_finalize(), secp256k1_rfc6979_hmac_sha256_generate(), secp256k1_rfc6979_hmac_sha256_initialize(), secp256k1_scalar_clear(), secp256k1_scalar_get_b32(), secp256k1_scalar_is_zero(), secp256k1_scalar_negate(), secp256k1_scalar_set_b32(), and secp256k1_scalar_set_int().

Referenced by secp256k1_ecmult_gen_context_build().

secp256k1_ecmult_gen_context_build()

static void secp256k1_ecmult_gen_context_build ( secp256k1_ecmult_gen_context *  ctx, const secp256k1_callback *  cb  )

static

Definition at line 21 of file ecmult_gen_impl.h.

References checked_malloc(), ctx, secp256k1_ecmult_gen_blind(), secp256k1_fe_set_b32(), secp256k1_ge_const_g, secp256k1_ge_set_all_gej_var(), secp256k1_ge_set_xo_var(), secp256k1_ge_to_storage(), secp256k1_gej_add_ge_var(), secp256k1_gej_add_var(), secp256k1_gej_double_var(), secp256k1_gej_neg(), secp256k1_gej_set_ge(), and VERIFY_CHECK.

secp256k1_ecmult_gen_context_clear()

static void secp256k1_ecmult_gen_context_clear ( secp256k1_ecmult_gen_context *  ctx )

static

Definition at line 115 of file ecmult_gen_impl.h.

References ctx, secp256k1_gej_clear(), and secp256k1_scalar_clear().

secp256k1_ecmult_gen_context_clone()

static void secp256k1_ecmult_gen_context_clone ( secp256k1_ecmult_gen_context *  dst, const secp256k1_ecmult_gen_context *  src, const secp256k1_callback *  cb  )

static

Definition at line 98 of file ecmult_gen_impl.h.

References secp256k1_ecmult_gen_context::blind, checked_malloc(), secp256k1_ecmult_gen_context::initial, memcpy(), and secp256k1_ecmult_gen_context::prec.

secp256k1_ecmult_gen_context_init()

static void secp256k1_ecmult_gen_context_init ( secp256k1_ecmult_gen_context *  ctx )

static

Definition at line 17 of file ecmult_gen_impl.h.

References ctx.

secp256k1_ecmult_gen_context_is_built()

static int secp256k1_ecmult_gen_context_is_built ( const secp256k1_ecmult_gen_context *  ctx )

static

Definition at line 94 of file ecmult_gen_impl.h.

References ctx.