diff --git a/src/scalar_impl.h b/src/scalar_impl.h index f5b2376407bd3..eb538cb499077 100644 --- a/src/scalar_impl.h +++ b/src/scalar_impl.h @@ -66,76 +66,70 @@ static void secp256k1_scalar_inverse(secp256k1_scalar *r, const secp256k1_scalar #else secp256k1_scalar *t; int i; - /* First compute x ^ (2^N - 1) for some values of N. */ - secp256k1_scalar x2, x3, x4, x6, x7, x8, x15, x30, x60, x120, x127; + /* First compute xN as x ^ (2^N - 1) for some values of N, + * and uM as x ^ M for some values of M. */ + secp256k1_scalar x2, x3, x6, x8, x14, x28, x56, x112, x126; + secp256k1_scalar u2, u5; - secp256k1_scalar_sqr(&x2, x); - secp256k1_scalar_mul(&x2, &x2, x); + secp256k1_scalar_sqr(&u2, x); + secp256k1_scalar_mul(&x2, &u2, x); + secp256k1_scalar_mul(&u5, &u2, &x2); + secp256k1_scalar_mul(&x3, &u5, &u2); - secp256k1_scalar_sqr(&x3, &x2); - secp256k1_scalar_mul(&x3, &x3, x); - - secp256k1_scalar_sqr(&x4, &x3); - secp256k1_scalar_mul(&x4, &x4, x); - - secp256k1_scalar_sqr(&x6, &x4); - secp256k1_scalar_sqr(&x6, &x6); - secp256k1_scalar_mul(&x6, &x6, &x2); - - secp256k1_scalar_sqr(&x7, &x6); - secp256k1_scalar_mul(&x7, &x7, x); + secp256k1_scalar_sqr(&x6, &x3); + for (i = 0; i < 2; i++) { + secp256k1_scalar_sqr(&x6, &x6); + } + secp256k1_scalar_mul(&x6, &x6, &x3); - secp256k1_scalar_sqr(&x8, &x7); - secp256k1_scalar_mul(&x8, &x8, x); + secp256k1_scalar_sqr(&x8, &x6); + secp256k1_scalar_sqr(&x8, &x8); + secp256k1_scalar_mul(&x8, &x8, &x2); - secp256k1_scalar_sqr(&x15, &x8); - for (i = 0; i < 6; i++) { - secp256k1_scalar_sqr(&x15, &x15); + secp256k1_scalar_sqr(&x14, &x8); + for (i = 0; i < 5; i++) { + secp256k1_scalar_sqr(&x14, &x14); } - secp256k1_scalar_mul(&x15, &x15, &x7); + secp256k1_scalar_mul(&x14, &x14, &x6); - secp256k1_scalar_sqr(&x30, &x15); - for (i = 0; i < 14; i++) { - secp256k1_scalar_sqr(&x30, &x30); + secp256k1_scalar_sqr(&x28, &x14); + for (i = 0; i < 13; i++) { + secp256k1_scalar_sqr(&x28, &x28); } - secp256k1_scalar_mul(&x30, &x30, &x15); + secp256k1_scalar_mul(&x28, &x28, &x14); - secp256k1_scalar_sqr(&x60, &x30); - for (i = 0; i < 29; i++) { - secp256k1_scalar_sqr(&x60, &x60); + secp256k1_scalar_sqr(&x56, &x28); + for (i = 0; i < 27; i++) { + secp256k1_scalar_sqr(&x56, &x56); } - secp256k1_scalar_mul(&x60, &x60, &x30); + secp256k1_scalar_mul(&x56, &x56, &x28); - secp256k1_scalar_sqr(&x120, &x60); - for (i = 0; i < 59; i++) { - secp256k1_scalar_sqr(&x120, &x120); + secp256k1_scalar_sqr(&x112, &x56); + for (i = 0; i < 55; i++) { + secp256k1_scalar_sqr(&x112, &x112); } - secp256k1_scalar_mul(&x120, &x120, &x60); + secp256k1_scalar_mul(&x112, &x112, &x56); - secp256k1_scalar_sqr(&x127, &x120); - for (i = 0; i < 6; i++) { - secp256k1_scalar_sqr(&x127, &x127); + secp256k1_scalar_sqr(&x126, &x112); + for (i = 0; i < 13; i++) { + secp256k1_scalar_sqr(&x126, &x126); } - secp256k1_scalar_mul(&x127, &x127, &x7); + secp256k1_scalar_mul(&x126, &x126, &x14); - /* Then accumulate the final result (t starts at x127). */ - t = &x127; - for (i = 0; i < 2; i++) { /* 0 */ + /* Then accumulate the final result (t starts at x126). */ + t = &x126; + for (i = 0; i < 3; i++) { secp256k1_scalar_sqr(t, t); } - secp256k1_scalar_mul(t, t, x); /* 1 */ + secp256k1_scalar_mul(t, t, &u5); /* 101 */ for (i = 0; i < 4; i++) { /* 0 */ secp256k1_scalar_sqr(t, t); } secp256k1_scalar_mul(t, t, &x3); /* 111 */ - for (i = 0; i < 2; i++) { /* 0 */ - secp256k1_scalar_sqr(t, t); - } - secp256k1_scalar_mul(t, t, x); /* 1 */ - for (i = 0; i < 2; i++) { /* 0 */ + for (i = 0; i < 4; i++) { /* 0 */ secp256k1_scalar_sqr(t, t); } - secp256k1_scalar_mul(t, t, x); /* 1 */ + secp256k1_scalar_mul(t, t, &u5); /* 101 */ for (i = 0; i < 2; i++) { /* 0 */ secp256k1_scalar_sqr(t, t); } @@ -160,34 +154,26 @@ static void secp256k1_scalar_inverse(secp256k1_scalar *r, const secp256k1_scalar secp256k1_scalar_sqr(t, t); } secp256k1_scalar_mul(t, t, &x2); /* 11 */ - for (i = 0; i < 2; i++) { /* 0 */ - secp256k1_scalar_sqr(t, t); - } - secp256k1_scalar_mul(t, t, x); /* 1 */ - for (i = 0; i < 2; i++) { /* 0 */ + for (i = 0; i < 4; i++) { /* 0 */ secp256k1_scalar_sqr(t, t); } - secp256k1_scalar_mul(t, t, x); /* 1 */ - for (i = 0; i < 5; i++) { /* 0 */ + secp256k1_scalar_mul(t, t, &u5); /* 101 */ + for (i = 0; i < 4; i++) { /* 0 */ secp256k1_scalar_sqr(t, t); } - secp256k1_scalar_mul(t, t, &x4); /* 1111 */ - for (i = 0; i < 2; i++) { /* 0 */ + secp256k1_scalar_mul(t, t, &x3); /* 111 */ + for (i = 0; i < 3; i++) { secp256k1_scalar_sqr(t, t); } - secp256k1_scalar_mul(t, t, x); /* 1 */ + secp256k1_scalar_mul(t, t, &u5); /* 101 */ for (i = 0; i < 3; i++) { /* 00 */ secp256k1_scalar_sqr(t, t); } secp256k1_scalar_mul(t, t, x); /* 1 */ - for (i = 0; i < 4; i++) { /* 000 */ - secp256k1_scalar_sqr(t, t); - } - secp256k1_scalar_mul(t, t, x); /* 1 */ - for (i = 0; i < 2; i++) { /* 0 */ + for (i = 0; i < 6; i++) { /* 000 */ secp256k1_scalar_sqr(t, t); } - secp256k1_scalar_mul(t, t, x); /* 1 */ + secp256k1_scalar_mul(t, t, &u5); /* 101 */ for (i = 0; i < 10; i++) { /* 0000000 */ secp256k1_scalar_sqr(t, t); } @@ -212,14 +198,14 @@ static void secp256k1_scalar_inverse(secp256k1_scalar *r, const secp256k1_scalar secp256k1_scalar_sqr(t, t); } secp256k1_scalar_mul(t, t, x); /* 1 */ - for (i = 0; i < 5; i++) { /* 0 */ + for (i = 0; i < 4; i++) { /* 0 */ secp256k1_scalar_sqr(t, t); } - secp256k1_scalar_mul(t, t, &x4); /* 1111 */ - for (i = 0; i < 2; i++) { /* 0 */ + secp256k1_scalar_mul(t, t, &x3); /* 111 */ + for (i = 0; i < 3; i++) { secp256k1_scalar_sqr(t, t); } - secp256k1_scalar_mul(t, t, x); /* 1 */ + secp256k1_scalar_mul(t, t, &u5); /* 101 */ for (i = 0; i < 5; i++) { /* 000 */ secp256k1_scalar_sqr(t, t); }