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Merge pull request bitcoin#196
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0768bd5 Get rid of variable-length hex string conversions (Pieter Wuille)
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@sipa
sipa committed Jan 25, 2015
2 parents e84e761 + 0768bd5 commit 7137be8
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Showing 5 changed files with 36 additions and 64 deletions.
8 changes: 4 additions & 4 deletions src/field.h
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Expand Up @@ -104,11 +104,11 @@ static void secp256k1_fe_inv_var(secp256k1_fe_t *r, const secp256k1_fe_t *a);
* outputs must not overlap in memory. */
static void secp256k1_fe_inv_all_var(size_t len, secp256k1_fe_t *r, const secp256k1_fe_t *a);

/** Convert a field element to a hexadecimal string. */
static void secp256k1_fe_get_hex(char *r, int *rlen, const secp256k1_fe_t *a);
/** Convert a field element to a 64-character hexadecimal string. */
static void secp256k1_fe_get_hex(char *r64, const secp256k1_fe_t *a);

/** Convert a hexadecimal string to a field element. */
static int secp256k1_fe_set_hex(secp256k1_fe_t *r, const char *a, int alen);
/** Convert a 64-character hexadecimal string to a field element. */
static int secp256k1_fe_set_hex(secp256k1_fe_t *r, const char *a64);

/** If flag is true, set *r equal to *a; otherwise leave it. Constant-time. */
static void secp256k1_fe_cmov(secp256k1_fe_t *r, const secp256k1_fe_t *a, int flag);
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19 changes: 6 additions & 13 deletions src/field_impl.h
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Expand Up @@ -21,29 +21,23 @@
#error "Please select field implementation"
#endif

static void secp256k1_fe_get_hex(char *r, int *rlen, const secp256k1_fe_t *a) {
static void secp256k1_fe_get_hex(char *r64, const secp256k1_fe_t *a) {
secp256k1_fe_t b;
int i;
unsigned char tmp[32];
if (*rlen < 65) {
*rlen = 65;
return;
}
*rlen = 65;
b = *a;
secp256k1_fe_normalize(&b);
secp256k1_fe_get_b32(tmp, &b);
for (i=0; i<32; i++) {
static const char *c = "0123456789ABCDEF";
r[2*i] = c[(tmp[i] >> 4) & 0xF];
r[2*i+1] = c[(tmp[i]) & 0xF];
r64[2*i] = c[(tmp[i] >> 4) & 0xF];
r64[2*i+1] = c[(tmp[i]) & 0xF];
}
r[64] = 0x00;
}

static int secp256k1_fe_set_hex(secp256k1_fe_t *r, const char *a, int alen) {
static int secp256k1_fe_set_hex(secp256k1_fe_t *r, const char *a64) {
int i;
unsigned char tmp[32] = {0};
unsigned char tmp[32];
static const int cvt[256] = {0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
Expand All @@ -61,8 +55,7 @@ static int secp256k1_fe_set_hex(secp256k1_fe_t *r, const char *a, int alen) {
0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0};
for (i=0; i<32; i++) {
if (alen > i*2)
tmp[32 - alen/2 + i] = (cvt[(unsigned char)a[2*i]] << 4) + cvt[(unsigned char)a[2*i+1]];
tmp[i] = (cvt[(unsigned char)a64[2*i]] << 4) + cvt[(unsigned char)a64[2*i+1]];
}
return secp256k1_fe_set_b32(r, tmp);
}
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8 changes: 4 additions & 4 deletions src/group.h
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Original file line number Diff line number Diff line change
Expand Up @@ -43,8 +43,8 @@ static int secp256k1_ge_is_valid_var(const secp256k1_ge_t *a);

static void secp256k1_ge_neg(secp256k1_ge_t *r, const secp256k1_ge_t *a);

/** Get a hex representation of a point. *rlen will be overwritten with the real length. */
static void secp256k1_ge_get_hex(char *r, int *rlen, const secp256k1_ge_t *a);
/** Get a 131-character hex representation of a point. */
static void secp256k1_ge_get_hex(char *r131, const secp256k1_ge_t *a);

/** Set a group element equal to another which is given in jacobian coordinates */
static void secp256k1_ge_set_gej(secp256k1_ge_t *r, secp256k1_gej_t *a);
Expand Down Expand Up @@ -85,8 +85,8 @@ static void secp256k1_gej_add_ge(secp256k1_gej_t *r, const secp256k1_gej_t *a, c
guarantee, and b is allowed to be infinity. */
static void secp256k1_gej_add_ge_var(secp256k1_gej_t *r, const secp256k1_gej_t *a, const secp256k1_ge_t *b);

/** Get a hex representation of a point. *rlen will be overwritten with the real length. */
static void secp256k1_gej_get_hex(char *r, int *rlen, const secp256k1_gej_t *a);
/** Get a 131-character hex representation of a point. */
static void secp256k1_gej_get_hex(char *r131, const secp256k1_gej_t *a);

#ifdef USE_ENDOMORPHISM
/** Set r to be equal to lambda times a, where lambda is chosen in a way such that this is very fast. */
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31 changes: 8 additions & 23 deletions src/group_impl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -45,25 +45,12 @@ static void secp256k1_ge_neg(secp256k1_ge_t *r, const secp256k1_ge_t *a) {
secp256k1_fe_negate(&r->y, &r->y, 1);
}

static void secp256k1_ge_get_hex(char *r, int *rlen, const secp256k1_ge_t *a) {
char cx[65]; int lx=65;
char cy[65]; int ly=65;
secp256k1_fe_get_hex(cx, &lx, &a->x);
secp256k1_fe_get_hex(cy, &ly, &a->y);
lx = strlen(cx);
ly = strlen(cy);
int len = lx + ly + 3 + 1;
if (*rlen < len) {
*rlen = len;
return;
}
*rlen = len;
r[0] = '(';
memcpy(r+1, cx, lx);
r[1+lx] = ',';
memcpy(r+2+lx, cy, ly);
r[2+lx+ly] = ')';
r[3+lx+ly] = 0;
static void secp256k1_ge_get_hex(char *r131, const secp256k1_ge_t *a) {
r131[0] = '(';
secp256k1_fe_get_hex(r131 + 1, &a->x);
r131[65] = ',';
secp256k1_fe_get_hex(r131 + 66, &a->y);
r131[130] = ')';
}

static void secp256k1_ge_set_gej(secp256k1_ge_t *r, secp256k1_gej_t *a) {
Expand Down Expand Up @@ -399,12 +386,10 @@ static void secp256k1_gej_add_ge(secp256k1_gej_t *r, const secp256k1_gej_t *a, c
r->infinity = infinity;
}



static void secp256k1_gej_get_hex(char *r, int *rlen, const secp256k1_gej_t *a) {
static void secp256k1_gej_get_hex(char *r131, const secp256k1_gej_t *a) {
secp256k1_gej_t c = *a;
secp256k1_ge_t t; secp256k1_ge_set_gej(&t, &c);
secp256k1_ge_get_hex(r, rlen, &t);
secp256k1_ge_get_hex(r131, &t);
}

#ifdef USE_ENDOMORPHISM
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34 changes: 14 additions & 20 deletions src/tests.c
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Original file line number Diff line number Diff line change
Expand Up @@ -928,8 +928,8 @@ void run_ge(void) {

void run_ecmult_chain(void) {
/* random starting point A (on the curve) */
secp256k1_fe_t ax; VERIFY_CHECK(secp256k1_fe_set_hex(&ax, "8b30bbe9ae2a990696b22f670709dff3727fd8bc04d3362c6c7bf458e2846004", 64));
secp256k1_fe_t ay; VERIFY_CHECK(secp256k1_fe_set_hex(&ay, "a357ae915c4a65281309edf20504740f0eb3343990216b4f81063cb65f2f7e0f", 64));
secp256k1_fe_t ax; VERIFY_CHECK(secp256k1_fe_set_hex(&ax, "8b30bbe9ae2a990696b22f670709dff3727fd8bc04d3362c6c7bf458e2846004"));
secp256k1_fe_t ay; VERIFY_CHECK(secp256k1_fe_set_hex(&ay, "a357ae915c4a65281309edf20504740f0eb3343990216b4f81063cb65f2f7e0f"));
secp256k1_gej_t a; secp256k1_gej_set_xy(&a, &ax, &ay);
/* two random initial factors xn and gn */
static const unsigned char xni[32] = {
Expand Down Expand Up @@ -976,19 +976,18 @@ void run_ecmult_chain(void) {

/* verify */
if (i == 19999) {
char res[132]; int resl = 132;
secp256k1_gej_get_hex(res, &resl, &x);
CHECK(strcmp(res, "(D6E96687F9B10D092A6F35439D86CEBEA4535D0D409F53586440BD74B933E830,B95CBCA2C77DA786539BE8FD53354D2D3B4F566AE658045407ED6015EE1B2A88)") == 0);
char res[131];
secp256k1_gej_get_hex(res, &x);
CHECK(memcmp(res, "(D6E96687F9B10D092A6F35439D86CEBEA4535D0D409F53586440BD74B933E830,B95CBCA2C77DA786539BE8FD53354D2D3B4F566AE658045407ED6015EE1B2A88)", 131) == 0);
}
}
/* redo the computation, but directly with the resulting ae and ge coefficients: */
secp256k1_gej_t x2; secp256k1_ecmult(&x2, &a, &ae, &ge);
char res[132]; int resl = 132;
char res2[132]; int resl2 = 132;
secp256k1_gej_get_hex(res, &resl, &x);
secp256k1_gej_get_hex(res2, &resl2, &x2);
CHECK(strcmp(res, res2) == 0);
CHECK(strlen(res) == 131);
char res[131];
char res2[131];
secp256k1_gej_get_hex(res, &x);
secp256k1_gej_get_hex(res2, &x2);
CHECK(memcmp(res, res2, 131) == 0);
}

void test_point_times_order(const secp256k1_gej_t *point) {
Expand All @@ -1015,7 +1014,7 @@ void test_point_times_order(const secp256k1_gej_t *point) {
}

void run_point_times_order(void) {
secp256k1_fe_t x; VERIFY_CHECK(secp256k1_fe_set_hex(&x, "02", 2));
secp256k1_fe_t x; VERIFY_CHECK(secp256k1_fe_set_hex(&x, "0000000000000000000000000000000000000000000000000000000000000002"));
for (int i=0; i<500; i++) {
secp256k1_ge_t p;
if (secp256k1_ge_set_xo_var(&p, &x, 1)) {
Expand All @@ -1027,14 +1026,9 @@ void run_point_times_order(void) {
}
secp256k1_fe_sqr(&x, &x);
}
char c[65];
int cl = 1;
c[1] = 123;
secp256k1_fe_get_hex(c, &cl, &x); /* Check that fe_get_hex handles a too short input. */
CHECK(c[1] == 123);
cl = 65;
secp256k1_fe_get_hex(c, &cl, &x);
CHECK(strcmp(c, "7603CB59B0EF6C63FE6084792A0C378CDB3233A80F8A9A09A877DEAD31B38C45") == 0);
char c[64];
secp256k1_fe_get_hex(c, &x);
CHECK(memcmp(c, "7603CB59B0EF6C63FE6084792A0C378CDB3233A80F8A9A09A877DEAD31B38C45", 64) == 0);
}

void test_wnaf(const secp256k1_scalar_t *number, int w) {
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