diff options
Diffstat (limited to 'ext/solv_ed25519.h')
| -rw-r--r-- | ext/solv_ed25519.h | 408 |
1 files changed, 408 insertions, 0 deletions
diff --git a/ext/solv_ed25519.h b/ext/solv_ed25519.h new file mode 100644 index 0000000..0772cee --- /dev/null +++ b/ext/solv_ed25519.h @@ -0,0 +1,408 @@ +/* + * Copyright (c) 2020, SUSE LLC. + * + * This program is licensed under the BSD license, read LICENSE.BSD + * for further information + */ + +/* simple and slow ed25519 verification code. */ + +#ifndef LIBSOLV_CHKSUM_H +#include "chksum.h" +#endif + +#define MPED25519_LEN (32 / MP_T_BYTES) + +#if MP_T_BYTES == 4 +# define MPED25519_CONST1(x) (mp_t)x +#elif MP_T_BYTES == 1 +# define MPED25519_CONST1(x) (mp_t)(x >> 0), (mp_t)(x >> 8), (mp_t)(x >> 16), (mp_t)(x >> 24) +#endif + +#define MPED25519_CONST(a, b, c, d, e, f, g, h) { \ + MPED25519_CONST1(h), MPED25519_CONST1(g), MPED25519_CONST1(f), MPED25519_CONST1(e), \ + MPED25519_CONST1(d), MPED25519_CONST1(c), MPED25519_CONST1(b), MPED25519_CONST1(a) \ +} + +static mp_t ed25519_q[] = /* mod prime */ + MPED25519_CONST(0x7FFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFED); +static mp_t ed25519_d[] = /* -(121665/121666) */ + MPED25519_CONST(0x52036CEE, 0x2B6FFE73, 0x8CC74079, 0x7779E898, 0x00700A4D, 0x4141D8AB, 0x75EB4DCA, 0x135978A3); +static mp_t ed25519_sqrtm1[] = /* sqrt(-1) */ + MPED25519_CONST(0x2B832480, 0x4FC1DF0B, 0x2B4D0099, 0x3DFBD7A7, 0x2F431806, 0xAD2FE478, 0xC4EE1B27, 0x4A0EA0B0); +static mp_t ed25519_l[] = /* order of base point */ + MPED25519_CONST(0x10000000, 0x00000000, 0x00000000, 0x00000000, 0x14DEF9DE, 0xA2F79CD6, 0x5812631A, 0x5CF5D3ED); +static mp_t ed25519_gx[] = /* base point */ + MPED25519_CONST(0x216936D3, 0xCD6E53FE, 0xC0A4E231, 0xFDD6DC5C, 0x692CC760, 0x9525A7B2, 0xC9562D60, 0x8F25D51A); +static mp_t ed25519_gy[] = /* base point */ + MPED25519_CONST(0x66666666, 0x66666666, 0x66666666, 0x66666666, 0x66666666, 0x66666666, 0x66666666, 0x66666658); +static mp_t ed25519_one[] = /* 1 */ + MPED25519_CONST(0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000001); + +/* small helpers to save some typing */ +static inline void +mped25519_add(mp_t *target, mp_t *m1, mp_t *m2) +{ + mpadd(MPED25519_LEN, target, m1, m2, ed25519_q); +} + +static inline void +mped25519_sub(mp_t *target, mp_t *m1, mp_t *m2) +{ + mpsub(MPED25519_LEN, target, m1, m2, ed25519_q); +} + +/* target = 512 bit input modulo ed25519_q */ +static void +mped25519_reduce512(mp_t *target, mp_t *a) +{ + int i; + mp2_t x; + + for (x = 0, i = 0; i < MPED25519_LEN; i++) + { + x += (mp2_t)a[i] + (mp2_t)a[i + MPED25519_LEN] * 38; + target[i] = x; + x >>= MP_T_BITS; + } + x *= 38; + if ((target[MPED25519_LEN - 1] & (1 << (MP_T_BITS - 1))) != 0) + { + x += 19; + target[MPED25519_LEN - 1] -= 1 << (MP_T_BITS - 1); + } + for (i = 0; x && i < MPED25519_LEN; i++) + { + x += (mp2_t)target[i]; + target[i] = x; + x >>= MP_T_BITS; + } + if (target[MPED25519_LEN - 1] > ed25519_q[MPED25519_LEN - 1] || + (target[MPED25519_LEN - 1] == ed25519_q[MPED25519_LEN - 1] && !mpisless(MPED25519_LEN - 1, target, ed25519_q))) + mpsubmod(MPED25519_LEN, target, ed25519_q); +} + +static void +mped25519_mul(mp_t *target, mp_t *m1, mp_t *m2) +{ + mp_t tmp[MPED25519_LEN * 2]; + int i, j; + mp2_t x; + + mpzero(MPED25519_LEN * 2, tmp); + for (i = 0; i < MPED25519_LEN; i++) + { + for (x = 0, j = 0; j < MPED25519_LEN; j++) + { + x += (mp2_t)tmp[i + j] + (mp2_t)m1[i] * m2[j]; + tmp[i + j] = x; + x >>= MP_T_BITS; + } + tmp[i + j] = x; + } + mped25519_reduce512(target, tmp); +} + +static inline void +mped25519_sqr(mp_t *target, mp_t *m) +{ + mped25519_mul(target, m, m); +} + +/* target = a ^ (2^252 - 4), a11 = a ^ 11 */ +static void +mped25519_pow_252_4(mp_t *target, mp_t *a, mp_t *a_11) +{ + static const int todo[16] = { 0, 5, 1, 10, 2, 20, 3, 10, 2, 50, 5, 100, 6, 50, 5, 2 }; + mp_t data[9][MPED25519_LEN]; + int i, j; + + mpcpy(MPED25519_LEN, target, a); + mped25519_sqr(target, target); + mpcpy(MPED25519_LEN, a_11, target); + mped25519_sqr(target, target); + mped25519_sqr(target, target); + mped25519_mul(data[0], target, a); /* data[0] = 9 */ + mped25519_mul(a_11, data[0], a_11); /* a_11 = 11 */ + mped25519_mul(target, a_11, a_11); /* target = 22 */ + for (i = 0; i < 8; i++) + { + mped25519_mul(target, target, data[todo[i * 2]]); + mpcpy(MPED25519_LEN, data[i + 1], target); + for (j = todo[i * 2 + 1]; j-- > 0;) + mped25519_sqr(target, target); + } +} + +/* target = a ^ (2^252 - 3) */ +static void +mped25519_pow_252_3(mp_t *target, mp_t *a) +{ + mp_t t11[MPED25519_LEN]; + mped25519_pow_252_4(target, a, t11); + mped25519_mul(target, target, a); +} + +/* target = a ^ -1 = a ^ (2^255 - 21) */ +static void +mped25519_inv(mp_t *target, mp_t *a) +{ + mp_t t[MPED25519_LEN], t11[MPED25519_LEN]; + mped25519_pow_252_4(t, a, t11); + mped25519_sqr(t, t); + mped25519_sqr(t, t); + mped25519_sqr(t, t); /* 2^255 - 32 */ + mped25519_mul(target, t, t11); +} + +static void +mped25519_reduce512_l(mp_t *target, mp_t *a) +{ + mp_t tmp[MPED25519_LEN]; + mpzero(MPED25519_LEN, target); + mpmul_add(MPED25519_LEN, target, ed25519_one, MPED25519_LEN * 2, a, tmp, ed25519_l); +} + +/* recover x coordinate from y and sign */ +static int +mped25519_recover_x(mp_t *x, mp_t *y, int sign) +{ + mp_t num[MPED25519_LEN], den[MPED25519_LEN]; + mp_t tmp1[MPED25519_LEN], tmp2[MPED25519_LEN]; + + if (!mpisless(MPED25519_LEN, y, ed25519_q)) + return 0; + /* calculate num=y^2-1 and den=dy^2+1 */ + mped25519_sqr(num, y); + mped25519_mul(den, num, ed25519_d); + mped25519_sub(num, num, ed25519_one); + mped25519_add(den, den, ed25519_one); + + /* calculate x = num*den^3 * (num*den^7)^((q-5)/8) */ + mped25519_sqr(tmp1, den); /* tmp1 = den^2 */ + mped25519_mul(tmp2, tmp1, den); /* tmp2 = den^3 */ + mped25519_sqr(tmp1, tmp2); /* tmp1 = den^6 */ + mped25519_mul(x, tmp1, den); /* x = den^7 */ + mped25519_mul(tmp1, x, num); /* tmp1 = num * den^7 */ + mped25519_pow_252_3(x, tmp1); /* x = tmp1^((q-5)/8) */ + mped25519_mul(tmp1, x, tmp2); /* tmp1 = x * den^3 */ + mped25519_mul(x, tmp1, num); /* x = tmp1 * num */ + + /* check if den*x^2 == num */ + mped25519_sqr(tmp2, x); + mped25519_mul(tmp1, tmp2, den); + if (!mpisequal(MPED25519_LEN, tmp1, num)) { + mped25519_mul(x, x, ed25519_sqrtm1); /* x = x * sqrt(-1) */ + mped25519_sqr(tmp2, x); + mped25519_mul(tmp1, tmp2, den); + if (!mpisequal(MPED25519_LEN, tmp1, num)) + return 0; + } + if (mpiszero(MPED25519_LEN, x)) + return 0; /* (0,1) is bad */ + if ((x[0] & 1) != sign) + mped25519_sub(x, ed25519_q, x); + return 1; +} + +/* see https://hyperelliptic.org/EFD/g1p/auto-twisted-projective.html */ +/* M=7 add=6 */ +static void +mped25519_ptdouble(mp_t *p_x, mp_t *p_y, mp_t *p_z) +{ + mp_t B[MPED25519_LEN], C[MPED25519_LEN], D[MPED25519_LEN]; + mp_t F[MPED25519_LEN], H[MPED25519_LEN], J[MPED25519_LEN]; + + mped25519_add(C, p_x, p_y); + mped25519_sqr(B, C); + mped25519_sqr(C, p_x); + mped25519_sqr(D, p_y); + mped25519_sub(F, C, D); + mped25519_sqr(H, p_z); + mped25519_add(H, H, H); + mped25519_add(J, F, H); + mped25519_add(H, C, D); + mped25519_mul(p_y, H, F); + mped25519_mul(p_z, J, F); + mped25519_sub(H, H, B); + mped25519_mul(p_x, J, H); +} + +/* M=12 add=7 */ +static void +mped25519_ptadd(mp_t *p_x, mp_t *p_y, mp_t *p_z, mp_t *q_x, mp_t *q_y, mp_t *q_z) +{ + mp_t A[MPED25519_LEN], B[MPED25519_LEN], C[MPED25519_LEN]; + mp_t D[MPED25519_LEN], E[MPED25519_LEN], F[MPED25519_LEN]; + mp_t G[MPED25519_LEN], H[MPED25519_LEN], J[MPED25519_LEN]; + + mped25519_mul(A, p_z, q_z); + mped25519_sqr(B, A); + mped25519_mul(C, p_x, q_x); + mped25519_mul(D, p_y, q_y); + mped25519_mul(F, ed25519_d, C); + mped25519_mul(E, F, D); + mped25519_sub(F, B, E); + mped25519_add(G, B, E); + mped25519_add(H, p_x, p_y); + mped25519_add(J, q_x, q_y); + mped25519_mul(p_x, H, J); + mped25519_sub(p_x, p_x, C); + mped25519_sub(p_x, p_x, D); + mped25519_mul(H, p_x, F); + mped25519_mul(p_x, H, A); + mped25519_add(H, D, C); + mped25519_mul(J, H, G); + mped25519_mul(p_y, J, A); + mped25519_mul(p_z, F, G); +} + +static inline void +mped25519_ptcpy(mp_t *p_x, mp_t *p_y, mp_t *p_z, mp_t *q_x, mp_t *q_y, mp_t *q_z) +{ + mpcpy(MPED25519_LEN, p_x, q_x); + mpcpy(MPED25519_LEN, p_y, q_y); + mpcpy(MPED25519_LEN, p_z, q_z); +} + +#if 0 +static void +mped25519_mpdump(mp_t *p, char *s, int c) +{ + if (c) + fprintf(stderr, "%c.", c); + mpdump(MPED25519_LEN, p, s); +} + +static void +mped25519_ptdump(mp_t *p_x, mp_t *p_y, mp_t *p_z, char *s) +{ + mp_t zi[MPED25519_LEN], px[MPED25519_LEN], py[MPED25519_LEN]; + mped25519_mpdump(p_x, s, 'X'); + mped25519_mpdump(p_y, s, 'Y'); + mped25519_mpdump(p_z, s, 'Z'); + mped25519_inv(zi, p_z); + mped25519_mul(px, p_x, zi); + mped25519_mul(py, p_y, zi); + mped25519_mpdump(px, s, 'x'); + mped25519_mpdump(py, s, 'y'); +} +#endif + + +/* scalar multiplication and add: r = s1*p1 + s2*p2 */ +/* needs about 13 + (256 - 32) / 2 = 125 point additions */ +static int +mped25519_scmult2(mp_t *r_x, mp_t *r_y, mp_t *s1, mp_t *p1_x, mp_t * p1_y, mp_t *s2, mp_t *p2_x, mp_t * p2_y) +{ + mp_t p_x[MPED25519_LEN], p_y[MPED25519_LEN], p_z[MPED25519_LEN]; + mp_t pi_z[MPED25519_LEN]; + mp_t tabx[16][MPED25519_LEN], taby[16][MPED25519_LEN], tabz[16][MPED25519_LEN]; + int i, x, dodouble = 0; + + mpzero(MPED25519_LEN, p_x); + mpzero(MPED25519_LEN, p_y); + mpzero(MPED25519_LEN, p_z); + p_y[0] = p_z[0] = 1; + + /* setup table: tab[i * 4 + j] = i * p1 + j * p2 */ + mped25519_ptcpy(tabx[0], taby[0], tabz[0], p_x, p_y, p_z); + for (i = 4; i < 16; i += 4) + mped25519_ptcpy(tabx[i], taby[i], tabz[i], p1_x, p1_y, ed25519_one); + mped25519_ptdouble(tabx[8], taby[8], tabz[8]); + mped25519_ptadd(tabx[12], taby[12], tabz[12], tabx[8], taby[8], tabz[8]); + mped25519_ptcpy(tabx[1], taby[1], tabz[1], p2_x, p2_y, ed25519_one); + for (i = 2; i < 16; i++) + { + if ((i & 3) == 0) + continue; + mped25519_ptcpy(tabx[i], taby[i], tabz[i], tabx[i - 1], taby[i - 1], tabz[i - 1]); + mped25519_ptadd(tabx[i], taby[i], tabz[i], p2_x, p2_y, ed25519_one); + } + /* now do the scalar multiplication */ + for (i = 255; i >= 0; i--) + { + if (dodouble) + mped25519_ptdouble(p_x, p_y, p_z); + x = s1[i / MP_T_BITS] & (1 << (i % MP_T_BITS)) ? 4 : 0; + x |= s2[i / MP_T_BITS] & (1 << (i % MP_T_BITS)) ? 1 : 0; + if (!x) + continue; + if (i > 0) + { + i--; + if (dodouble) + mped25519_ptdouble(p_x, p_y, p_z); + x <<= 1; + x |= s1[i / MP_T_BITS] & (1 << (i % MP_T_BITS)) ? 4 : 0; + x |= s2[i / MP_T_BITS] & (1 << (i % MP_T_BITS)) ? 1 : 0; + } + mped25519_ptadd(p_x, p_y, p_z, tabx[x], taby[x], tabz[x]); + dodouble = 1; + } +#if 0 + mped25519_ptdump(p_x, p_y, p_z, "r = "); +#endif + mped25519_inv(pi_z, p_z); + mped25519_mul(r_x, p_x, pi_z); + mped25519_mul(r_y, p_y, pi_z); + return mpiszero(MPED25519_LEN, p_z) ? 0 : 1; +} + +static void +mped25519_setfromle(int len, mp_t *out, const unsigned char *buf, int bufl, int highmask) +{ + unsigned char bebuf[64]; /* bufl must be <= 64 */ + int i; + for (i = 0; i < bufl; i++) + bebuf[bufl - 1 - i] = buf[i]; + bebuf[0] &= highmask; + mpsetfrombe(len, out, bebuf, bufl); +} + +static int +mped25519(const unsigned char *pub, const unsigned char *sig, const unsigned char *data, unsigned int datal) +{ + unsigned char hbuf[64], rbuf[32]; + int i; + mp_t pub_x[MPED25519_LEN], pub_y[MPED25519_LEN]; + mp_t h[MPED25519_LEN], s[MPED25519_LEN], h2[MPED25519_LEN * 2]; + mp_t r_x[MPED25519_LEN], r_y[MPED25519_LEN]; + Chksum *chk; + + mped25519_setfromle(MPED25519_LEN, s, sig + 32, 32, 0xff); + if (!mpisless(MPED25519_LEN, s, ed25519_l)) + return 0; /* bad s */ + /* uncompress pubkey, we invert the sign to get -pub */ + mped25519_setfromle(MPED25519_LEN, pub_y, pub, 32, 0x7f); + if (!mped25519_recover_x(pub_x, pub_y, pub[31] & 0x80 ? 0 : 1)) + return 0; /* bad pubkey */ +#if 0 + mped25519_mpdump(pub_x, "-pubx = ", 0); + mped25519_mpdump(pub_y, "puby = ", 0); +#endif + /* calculate h = H(sig[0..31]|pub|data) mod l */ + chk = solv_chksum_create(REPOKEY_TYPE_SHA512); + if (!chk) + return 0; + solv_chksum_add(chk, sig, 32); + solv_chksum_add(chk, pub, 32); + solv_chksum_add(chk, data, datal); + solv_chksum_free(chk, hbuf); + mped25519_setfromle(MPED25519_LEN * 2, h2, hbuf, 64, 0xff); + mped25519_reduce512_l(h, h2); +#if 0 + mped25519_mpdump(s, "s = ", 0); + mped25519_mpdump(h, "h = ", 0); +#endif + /* calculate r = s * G - h * pub */ + if (!mped25519_scmult2(r_x, r_y, s, ed25519_gx, ed25519_gy, h, pub_x, pub_y)) + return 0; + /* compress r into rbuf and verify that it matches sig */ + for (i = 0; i < 32; i++) + rbuf[i] = r_y[i / MP_T_BYTES] >> (8 * (i % MP_T_BYTES)); + if ((r_x[0] & 1) != 0) + rbuf[31] |= 0x80; + return memcmp(sig, rbuf, 32) == 0 ? 1 : 0; +} + |