frost/secp256k1-zkp
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Convert field code to strict C89 (+ long long, +__int128)

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This makes the software more portable to embedded systems
 and static analysis tools.

Sadly, it can't result in identical binaries because C99 mixed
 declarations seem to make GCC emit superfluous stack-pointer
 updates. The compiler is also somewhat dependent on the
 declaration order.
This commit is contained in:
Gregory Maxwell
2015-01-23 05:48:27 +00:00
parent 3627437d80
commit 25b35c7ecb
4 changed files with 190 additions and 147 deletions
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36
src/field_5x52_int128_impl.h
View File

@@ -16,6 +16,11 @@
#endif
SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t *a, const uint64_t * SECP256K1_RESTRICT b) {
__int128 c, d;
uint64_t t3, t4, tx, u0;
uint64_t a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3], a4 = a[4];
const uint64_t M = 0xFFFFFFFFFFFFFULL, R = 0x1000003D10ULL;
VERIFY_BITS(a[0], 56);
VERIFY_BITS(a[1], 56);
VERIFY_BITS(a[2], 56);
@@ -28,16 +33,11 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t
VERIFY_BITS(b[4], 52);
VERIFY_CHECK(r != b);
const uint64_t M = 0xFFFFFFFFFFFFFULL, R = 0x1000003D10ULL;
/* [... a b c] is a shorthand for ... + a<<104 + b<<52 + c<<0 mod n.
* px is a shorthand for sum(a[i]*b[x-i], i=0..x).
* Note that [x 0 0 0 0 0] = [x*R].
*/
uint64_t a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3], a4 = a[4];
__int128 c, d;
d = (__int128)a0 * b[3]
+ (__int128)a1 * b[2]
+ (__int128)a2 * b[1]
@@ -51,7 +51,7 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t
VERIFY_BITS(d, 115);
VERIFY_BITS(c, 60);
/* [c 0 0 0 0 0 d 0 0 0] = [p8 0 0 0 0 p3 0 0 0] */
uint64_t t3 = d & M; d >>= 52;
t3 = d & M; d >>= 52;
VERIFY_BITS(t3, 52);
VERIFY_BITS(d, 63);
/* [c 0 0 0 0 d t3 0 0 0] = [p8 0 0 0 0 p3 0 0 0] */
@@ -66,11 +66,11 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t
d += c * R;
VERIFY_BITS(d, 116);
/* [d t3 0 0 0] = [p8 0 0 0 p4 p3 0 0 0] */
uint64_t t4 = d & M; d >>= 52;
t4 = d & M; d >>= 52;
VERIFY_BITS(t4, 52);
VERIFY_BITS(d, 64);
/* [d t4 t3 0 0 0] = [p8 0 0 0 p4 p3 0 0 0] */
uint64_t tx = (t4 >> 48); t4 &= (M >> 4);
tx = (t4 >> 48); t4 &= (M >> 4);
VERIFY_BITS(tx, 4);
VERIFY_BITS(t4, 48);
/* [d t4+(tx<<48) t3 0 0 0] = [p8 0 0 0 p4 p3 0 0 0] */
@@ -84,7 +84,7 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t
+ (__int128)a4 * b[1];
VERIFY_BITS(d, 115);
/* [d t4+(tx<<48) t3 0 0 c] = [p8 0 0 p5 p4 p3 0 0 p0] */
uint64_t u0 = d & M; d >>= 52;
u0 = d & M; d >>= 52;
VERIFY_BITS(u0, 52);
VERIFY_BITS(d, 63);
/* [d u0 t4+(tx<<48) t3 0 0 c] = [p8 0 0 p5 p4 p3 0 0 p0] */
@@ -153,22 +153,22 @@ SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t
}
SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint64_t *r, const uint64_t *a) {
__int128 c, d;
uint64_t a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3], a4 = a[4];
int64_t t3, t4, tx, u0;
const uint64_t M = 0xFFFFFFFFFFFFFULL, R = 0x1000003D10ULL;
VERIFY_BITS(a[0], 56);
VERIFY_BITS(a[1], 56);
VERIFY_BITS(a[2], 56);
VERIFY_BITS(a[3], 56);
VERIFY_BITS(a[4], 52);
const uint64_t M = 0xFFFFFFFFFFFFFULL, R = 0x1000003D10ULL;
/** [... a b c] is a shorthand for ... + a<<104 + b<<52 + c<<0 mod n.
* px is a shorthand for sum(a[i]*a[x-i], i=0..x).
* Note that [x 0 0 0 0 0] = [x*R].
*/
__int128 c, d;
uint64_t a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3], a4 = a[4];
d = (__int128)(a0*2) * a3
+ (__int128)(a1*2) * a2;
VERIFY_BITS(d, 114);
@@ -180,7 +180,7 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint64_t *r, const uint64_t
VERIFY_BITS(d, 115);
VERIFY_BITS(c, 60);
/* [c 0 0 0 0 0 d 0 0 0] = [p8 0 0 0 0 p3 0 0 0] */
uint64_t t3 = d & M; d >>= 52;
t3 = d & M; d >>= 52;
VERIFY_BITS(t3, 52);
VERIFY_BITS(d, 63);
/* [c 0 0 0 0 d t3 0 0 0] = [p8 0 0 0 0 p3 0 0 0] */
@@ -194,11 +194,11 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint64_t *r, const uint64_t
d += c * R;
VERIFY_BITS(d, 116);
/* [d t3 0 0 0] = [p8 0 0 0 p4 p3 0 0 0] */
uint64_t t4 = d & M; d >>= 52;
t4 = d & M; d >>= 52;
VERIFY_BITS(t4, 52);
VERIFY_BITS(d, 64);
/* [d t4 t3 0 0 0] = [p8 0 0 0 p4 p3 0 0 0] */
uint64_t tx = (t4 >> 48); t4 &= (M >> 4);
tx = (t4 >> 48); t4 &= (M >> 4);
VERIFY_BITS(tx, 4);
VERIFY_BITS(t4, 48);
/* [d t4+(tx<<48) t3 0 0 0] = [p8 0 0 0 p4 p3 0 0 0] */
@@ -210,7 +210,7 @@ SECP256K1_INLINE static void secp256k1_fe_sqr_inner(uint64_t *r, const uint64_t
+ (__int128)(a2*2) * a3;
VERIFY_BITS(d, 114);
/* [d t4+(tx<<48) t3 0 0 c] = [p8 0 0 p5 p4 p3 0 0 p0] */
uint64_t u0 = d & M; d >>= 52;
u0 = d & M; d >>= 52;
VERIFY_BITS(u0, 52);
VERIFY_BITS(d, 62);
/* [d u0 t4+(tx<<48) t3 0 0 c] = [p8 0 0 p5 p4 p3 0 0 p0] */