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ecmult_impl.h File Reference
#include <string.h>
#include <stdint.h>
#include "group.h"
#include "scalar.h"
#include "ecmult.h"
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Classes

struct  secp256k1_strauss_point_state
 
struct  secp256k1_strauss_state
 
struct  secp256k1_pippenger_point_state
 
struct  secp256k1_pippenger_state
 

Macros

#define WINDOW_A   5
 
#define WINDOW_G   16
 larger numbers may result in slightly better performance, at the cost of exponentially larger precomputed tables. More...
 
#define WNAF_BITS   256
 
#define WNAF_SIZE_BITS(bits, w)   (((bits) + (w) - 1) / (w))
 
#define WNAF_SIZE(w)   WNAF_SIZE_BITS(WNAF_BITS, w)
 
#define ECMULT_TABLE_SIZE(w)   (1 << ((w)-2))
 The number of entries a table with precomputed multiples needs to have. More...
 
#define PIPPENGER_SCRATCH_OBJECTS   6
 
#define STRAUSS_SCRATCH_OBJECTS   6
 
#define PIPPENGER_MAX_BUCKET_WINDOW   12
 
#define ECMULT_PIPPENGER_THRESHOLD   160
 
#define ECMULT_MAX_POINTS_PER_BATCH   10000000
 
#define ECMULT_TABLE_GET_GE(r, pre, n, w)
 The following two macro retrieves a particular odd multiple from a table of precomputed multiples. More...
 
#define ECMULT_TABLE_GET_GE_STORAGE(r, pre, n, w)
 

Typedefs

typedef int(* secp256k1_ecmult_multi_func) (const secp256k1_ecmult_context *, secp256k1_scratch *, secp256k1_gej *, const secp256k1_scalar *, secp256k1_ecmult_multi_callback cb, void *, size_t)
 

Functions

static void secp256k1_ecmult_odd_multiples_table (int n, secp256k1_gej *prej, secp256k1_fe *zr, const secp256k1_gej *a)
 Fill a table 'prej' with precomputed odd multiples of a. More...
 
static void secp256k1_ecmult_odd_multiples_table_globalz_windowa (secp256k1_ge *pre, secp256k1_fe *globalz, const secp256k1_gej *a)
 Fill a table 'pre' with precomputed odd multiples of a. More...
 
static void secp256k1_ecmult_odd_multiples_table_storage_var (const int n, secp256k1_ge_storage *pre, const secp256k1_gej *a)
 
static void secp256k1_ecmult_context_init (secp256k1_ecmult_context *ctx)
 
static void secp256k1_ecmult_context_build (secp256k1_ecmult_context *ctx, const secp256k1_callback *cb)
 
static void secp256k1_ecmult_context_clone (secp256k1_ecmult_context *dst, const secp256k1_ecmult_context *src, const secp256k1_callback *cb)
 
static int secp256k1_ecmult_context_is_built (const secp256k1_ecmult_context *ctx)
 
static void secp256k1_ecmult_context_clear (secp256k1_ecmult_context *ctx)
 
static int secp256k1_ecmult_wnaf (int *wnaf, int len, const secp256k1_scalar *a, int w)
 Convert a number to WNAF notation. More...
 
static void secp256k1_ecmult_strauss_wnaf (const secp256k1_ecmult_context *ctx, const struct secp256k1_strauss_state *state, secp256k1_gej *r, int num, const secp256k1_gej *a, const secp256k1_scalar *na, const secp256k1_scalar *ng)
 
static void secp256k1_ecmult (const secp256k1_ecmult_context *ctx, secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_scalar *na, const secp256k1_scalar *ng)
 
static size_t secp256k1_strauss_scratch_size (size_t n_points)
 
static int secp256k1_ecmult_strauss_batch (const secp256k1_ecmult_context *ctx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n_points, size_t cb_offset)
 
static int secp256k1_ecmult_strauss_batch_single (const secp256k1_ecmult_context *actx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n)
 
static size_t secp256k1_strauss_max_points (secp256k1_scratch *scratch)
 
static int secp256k1_wnaf_fixed (int *wnaf, const secp256k1_scalar *s, int w)
 Convert a number to WNAF notation. More...
 
static int secp256k1_ecmult_pippenger_wnaf (secp256k1_gej *buckets, int bucket_window, struct secp256k1_pippenger_state *state, secp256k1_gej *r, const secp256k1_scalar *sc, const secp256k1_ge *pt, size_t num)
 
static int secp256k1_pippenger_bucket_window (size_t n)
 Returns optimal bucket_window (number of bits of a scalar represented by a set of buckets) for a given number of points. More...
 
static size_t secp256k1_pippenger_bucket_window_inv (int bucket_window)
 Returns the maximum optimal number of points for a bucket_window. More...
 
static size_t secp256k1_pippenger_scratch_size (size_t n_points, int bucket_window)
 Returns the scratch size required for a given number of points (excluding base point G) without considering alignment. More...
 
static int secp256k1_ecmult_pippenger_batch (const secp256k1_ecmult_context *ctx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n_points, size_t cb_offset)
 
static int secp256k1_ecmult_pippenger_batch_single (const secp256k1_ecmult_context *actx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n)
 
static size_t secp256k1_pippenger_max_points (secp256k1_scratch *scratch)
 Returns the maximum number of points in addition to G that can be used with a given scratch space. More...
 
static int secp256k1_ecmult_multi_simple_var (const secp256k1_ecmult_context *ctx, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n_points)
 
static int secp256k1_ecmult_multi_batch_size_helper (size_t *n_batches, size_t *n_batch_points, size_t max_n_batch_points, size_t n)
 
static int secp256k1_ecmult_multi_var (const secp256k1_ecmult_context *ctx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n)
 

Macro Definition Documentation

◆ ECMULT_MAX_POINTS_PER_BATCH

#define ECMULT_MAX_POINTS_PER_BATCH   10000000

Definition at line 72 of file ecmult_impl.h.

◆ ECMULT_PIPPENGER_THRESHOLD

#define ECMULT_PIPPENGER_THRESHOLD   160

Definition at line 66 of file ecmult_impl.h.

◆ ECMULT_TABLE_GET_GE

#define ECMULT_TABLE_GET_GE (   r,
  pre,
  n,
 
)
Value:
do { \
VERIFY_CHECK(((n) & 1) == 1); \
VERIFY_CHECK((n) >= -((1 << ((w)-1)) - 1)); \
VERIFY_CHECK((n) <= ((1 << ((w)-1)) - 1)); \
if ((n) > 0) { \
*(r) = (pre)[((n)-1)/2]; \
} else { \
*(r) = (pre)[(-(n)-1)/2]; \
secp256k1_fe_negate(&((r)->y), &((r)->y), 1); \
} \
} while(0)

The following two macro retrieves a particular odd multiple from a table of precomputed multiples.

Definition at line 273 of file ecmult_impl.h.

◆ ECMULT_TABLE_GET_GE_STORAGE

#define ECMULT_TABLE_GET_GE_STORAGE (   r,
  pre,
  n,
 
)
Value:
do { \
VERIFY_CHECK(((n) & 1) == 1); \
VERIFY_CHECK((n) >= -((1 << ((w)-1)) - 1)); \
VERIFY_CHECK((n) <= ((1 << ((w)-1)) - 1)); \
if ((n) > 0) { \
secp256k1_ge_from_storage((r), &(pre)[((n)-1)/2]); \
} else { \
secp256k1_ge_from_storage((r), &(pre)[(-(n)-1)/2]); \
secp256k1_fe_negate(&((r)->y), &((r)->y), 1); \
} \
} while(0)

Definition at line 285 of file ecmult_impl.h.

◆ ECMULT_TABLE_SIZE

#define ECMULT_TABLE_SIZE (   w)    (1 << ((w)-2))

The number of entries a table with precomputed multiples needs to have.

Definition at line 54 of file ecmult_impl.h.

◆ PIPPENGER_MAX_BUCKET_WINDOW

#define PIPPENGER_MAX_BUCKET_WINDOW   12

Definition at line 60 of file ecmult_impl.h.

◆ PIPPENGER_SCRATCH_OBJECTS

#define PIPPENGER_SCRATCH_OBJECTS   6

Definition at line 57 of file ecmult_impl.h.

◆ STRAUSS_SCRATCH_OBJECTS

#define STRAUSS_SCRATCH_OBJECTS   6

Definition at line 58 of file ecmult_impl.h.

◆ WINDOW_A

#define WINDOW_A   5

Definition at line 33 of file ecmult_impl.h.

◆ WINDOW_G

#define WINDOW_G   16

larger numbers may result in slightly better performance, at the cost of exponentially larger precomputed tables.

One table for window size 16: 1.375 MiB.

Definition at line 41 of file ecmult_impl.h.

◆ WNAF_BITS

#define WNAF_BITS   256

Definition at line 48 of file ecmult_impl.h.

◆ WNAF_SIZE

#define WNAF_SIZE (   w)    WNAF_SIZE_BITS(WNAF_BITS, w)

Definition at line 51 of file ecmult_impl.h.

◆ WNAF_SIZE_BITS

#define WNAF_SIZE_BITS (   bits,
 
)    (((bits) + (w) - 1) / (w))

Definition at line 50 of file ecmult_impl.h.

Typedef Documentation

◆ secp256k1_ecmult_multi_func

typedef int(* secp256k1_ecmult_multi_func) (const secp256k1_ecmult_context *, secp256k1_scratch *, secp256k1_gej *, const secp256k1_scalar *, secp256k1_ecmult_multi_callback cb, void *, size_t)

Definition at line 1134 of file ecmult_impl.h.

Function Documentation

◆ secp256k1_ecmult()

static void secp256k1_ecmult ( const secp256k1_ecmult_context ctx,
secp256k1_gej r,
const secp256k1_gej a,
const secp256k1_scalar na,
const secp256k1_scalar ng 
)
static

Definition at line 600 of file ecmult_impl.h.

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◆ secp256k1_ecmult_context_build()

static void secp256k1_ecmult_context_build ( secp256k1_ecmult_context ctx,
const secp256k1_callback cb 
)
static

Definition at line 304 of file ecmult_impl.h.

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◆ secp256k1_ecmult_context_clear()

static void secp256k1_ecmult_context_clear ( secp256k1_ecmult_context ctx)
static

Definition at line 360 of file ecmult_impl.h.

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◆ secp256k1_ecmult_context_clone()

static void secp256k1_ecmult_context_clone ( secp256k1_ecmult_context dst,
const secp256k1_ecmult_context src,
const secp256k1_callback cb 
)
static

Definition at line 336 of file ecmult_impl.h.

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◆ secp256k1_ecmult_context_init()

static void secp256k1_ecmult_context_init ( secp256k1_ecmult_context ctx)
static

Definition at line 297 of file ecmult_impl.h.

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◆ secp256k1_ecmult_context_is_built()

static int secp256k1_ecmult_context_is_built ( const secp256k1_ecmult_context ctx)
static

Definition at line 356 of file ecmult_impl.h.

◆ secp256k1_ecmult_multi_batch_size_helper()

static int secp256k1_ecmult_multi_batch_size_helper ( size_t *  n_batches,
size_t *  n_batch_points,
size_t  max_n_batch_points,
size_t  n 
)
static

Definition at line 1116 of file ecmult_impl.h.

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◆ secp256k1_ecmult_multi_simple_var()

static int secp256k1_ecmult_multi_simple_var ( const secp256k1_ecmult_context ctx,
secp256k1_gej r,
const secp256k1_scalar inp_g_sc,
secp256k1_ecmult_multi_callback  cb,
void *  cbdata,
size_t  n_points 
)
static

Definition at line 1089 of file ecmult_impl.h.

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◆ secp256k1_ecmult_multi_var()

static int secp256k1_ecmult_multi_var ( const secp256k1_ecmult_context ctx,
secp256k1_scratch scratch,
secp256k1_gej r,
const secp256k1_scalar inp_g_sc,
secp256k1_ecmult_multi_callback  cb,
void *  cbdata,
size_t  n 
)
static

Definition at line 1135 of file ecmult_impl.h.

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◆ secp256k1_ecmult_odd_multiples_table()

static void secp256k1_ecmult_odd_multiples_table ( int  n,
secp256k1_gej prej,
secp256k1_fe zr,
const secp256k1_gej a 
)
static

Fill a table 'prej' with precomputed odd multiples of a.

Prej will contain the values [1*a,3*a,...,(2*n-1)*a], so it space for n values. zr[0] will contain prej[0].z / a.z. The other zr[i] values = prej[i].z / prej[i-1].z. Prej's Z values are undefined, except for the last value.

Definition at line 80 of file ecmult_impl.h.

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◆ secp256k1_ecmult_odd_multiples_table_globalz_windowa()

static void secp256k1_ecmult_odd_multiples_table_globalz_windowa ( secp256k1_ge pre,
secp256k1_fe globalz,
const secp256k1_gej a 
)
static

Fill a table 'pre' with precomputed odd multiples of a.

There are two versions of this function:

  • secp256k1_ecmult_odd_multiples_table_globalz_windowa which brings its resulting point set to a single constant Z denominator, stores the X and Y coordinates as ge_storage points in pre, and stores the global Z in rz. It only operates on tables sized for WINDOW_A wnaf multiples.
  • secp256k1_ecmult_odd_multiples_table_storage_var, which converts its resulting point set to actually affine points, and stores those in pre. It operates on tables of any size, but uses heap-allocated temporaries.

To compute a*P + b*G, we compute a table for P using the first function, and for G using the second (which requires an inverse, but it only needs to happen once).

Definition at line 130 of file ecmult_impl.h.

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◆ secp256k1_ecmult_odd_multiples_table_storage_var()

static void secp256k1_ecmult_odd_multiples_table_storage_var ( const int  n,
secp256k1_ge_storage pre,
const secp256k1_gej a 
)
static

Definition at line 140 of file ecmult_impl.h.

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◆ secp256k1_ecmult_pippenger_batch()

static int secp256k1_ecmult_pippenger_batch ( const secp256k1_ecmult_context ctx,
secp256k1_scratch scratch,
secp256k1_gej r,
const secp256k1_scalar inp_g_sc,
secp256k1_ecmult_multi_callback  cb,
void *  cbdata,
size_t  n_points,
size_t  cb_offset 
)
static

Definition at line 966 of file ecmult_impl.h.

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◆ secp256k1_ecmult_pippenger_batch_single()

static int secp256k1_ecmult_pippenger_batch_single ( const secp256k1_ecmult_context actx,
secp256k1_scratch scratch,
secp256k1_gej r,
const secp256k1_scalar inp_g_sc,
secp256k1_ecmult_multi_callback  cb,
void *  cbdata,
size_t  n 
)
static

Definition at line 1042 of file ecmult_impl.h.

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◆ secp256k1_ecmult_pippenger_wnaf()

static int secp256k1_ecmult_pippenger_wnaf ( secp256k1_gej buckets,
int  bucket_window,
struct secp256k1_pippenger_state state,
secp256k1_gej r,
const secp256k1_scalar sc,
const secp256k1_ge pt,
size_t  num 
)
static

Definition at line 763 of file ecmult_impl.h.

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◆ secp256k1_ecmult_strauss_batch()

static int secp256k1_ecmult_strauss_batch ( const secp256k1_ecmult_context ctx,
secp256k1_scratch scratch,
secp256k1_gej r,
const secp256k1_scalar inp_g_sc,
secp256k1_ecmult_multi_callback  cb,
void *  cbdata,
size_t  n_points,
size_t  cb_offset 
)
static

Definition at line 629 of file ecmult_impl.h.

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◆ secp256k1_ecmult_strauss_batch_single()

static int secp256k1_ecmult_strauss_batch_single ( const secp256k1_ecmult_context actx,
secp256k1_scratch scratch,
secp256k1_gej r,
const secp256k1_scalar inp_g_sc,
secp256k1_ecmult_multi_callback  cb,
void *  cbdata,
size_t  n 
)
static

Definition at line 669 of file ecmult_impl.h.

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◆ secp256k1_ecmult_strauss_wnaf()

static void secp256k1_ecmult_strauss_wnaf ( const secp256k1_ecmult_context ctx,
const struct secp256k1_strauss_state state,
secp256k1_gej r,
int  num,
const secp256k1_gej a,
const secp256k1_scalar na,
const secp256k1_scalar ng 
)
static

Definition at line 450 of file ecmult_impl.h.

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◆ secp256k1_ecmult_wnaf()

static int secp256k1_ecmult_wnaf ( int *  wnaf,
int  len,
const secp256k1_scalar a,
int  w 
)
static

Convert a number to WNAF notation.

The number becomes represented by sum(2^i * wnaf[i], i=0..bits), with the following guarantees:

  • each wnaf[i] is either 0, or an odd integer between -(1<<(w-1) - 1) and (1<<(w-1) - 1)
  • two non-zero entries in wnaf are separated by at least w-1 zeroes.
  • the number of set values in wnaf is returned. This number is at most 256, and at most one more than the number of bits in the (absolute value) of the input.

Definition at line 375 of file ecmult_impl.h.

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◆ secp256k1_pippenger_bucket_window()

static int secp256k1_pippenger_bucket_window ( size_t  n)
static

Returns optimal bucket_window (number of bits of a scalar represented by a set of buckets) for a given number of points.

Definition at line 844 of file ecmult_impl.h.

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◆ secp256k1_pippenger_bucket_window_inv()

static size_t secp256k1_pippenger_bucket_window_inv ( int  bucket_window)
static

Returns the maximum optimal number of points for a bucket_window.

Definition at line 901 of file ecmult_impl.h.

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◆ secp256k1_pippenger_max_points()

static size_t secp256k1_pippenger_max_points ( secp256k1_scratch scratch)
static

Returns the maximum number of points in addition to G that can be used with a given scratch space.

The function ensures that fewer points may also be used.

Definition at line 1051 of file ecmult_impl.h.

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◆ secp256k1_pippenger_scratch_size()

static size_t secp256k1_pippenger_scratch_size ( size_t  n_points,
int  bucket_window 
)
static

Returns the scratch size required for a given number of points (excluding base point G) without considering alignment.

Definition at line 956 of file ecmult_impl.h.

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◆ secp256k1_strauss_max_points()

static size_t secp256k1_strauss_max_points ( secp256k1_scratch scratch)
static

Definition at line 673 of file ecmult_impl.h.

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◆ secp256k1_strauss_scratch_size()

static size_t secp256k1_strauss_scratch_size ( size_t  n_points)
static

Definition at line 620 of file ecmult_impl.h.

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◆ secp256k1_wnaf_fixed()

static int secp256k1_wnaf_fixed ( int *  wnaf,
const secp256k1_scalar s,
int  w 
)
static

Convert a number to WNAF notation.

The number becomes represented by sum(2^{wi} * wnaf[i], i=0..WNAF_SIZE(w)+1) - return_val. It has the following guarantees:

  • each wnaf[i] is either 0 or an odd integer between -(1 << w) and (1 << w)
  • the number of words set is always WNAF_SIZE(w)
  • the returned skew is 0 or 1

Definition at line 684 of file ecmult_impl.h.

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