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trezor-firmware/crypto/ed25519-donna/ed25519.c

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/*
Public domain by Andrew M. <liquidsun@gmail.com>
Ed25519 reference implementation using Ed25519-donna
*/
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/* define ED25519_SUFFIX to have it appended to the end of each public function */
#ifdef ED25519_SUFFIX
#define ED25519_FN3(fn,suffix) fn##suffix
#define ED25519_FN2(fn,suffix) ED25519_FN3(fn,suffix)
#define ED25519_FN(fn) ED25519_FN2(fn,ED25519_SUFFIX)
#else
#define ED25519_FN(fn) fn
#endif
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#include "ed25519-donna.h"
#include "ed25519.h"
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#include "ed25519-hash-custom.h"
#include "rand.h"
#include "memzero.h"
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/*
Generates a (extsk[0..31]) and aExt (extsk[32..63])
*/
DONNA_INLINE static void
ed25519_extsk(hash_512bits extsk, const ed25519_secret_key sk) {
ed25519_hash(extsk, sk, 32);
extsk[0] &= 248;
extsk[31] &= 127;
extsk[31] |= 64;
}
static void
ed25519_hram(hash_512bits hram, const ed25519_public_key R, const ed25519_public_key pk, const unsigned char *m, size_t mlen) {
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ed25519_hash_context ctx;
ed25519_hash_init(&ctx);
ed25519_hash_update(&ctx, R, 32);
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ed25519_hash_update(&ctx, pk, 32);
ed25519_hash_update(&ctx, m, mlen);
ed25519_hash_final(&ctx, hram);
}
void
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ED25519_FN(ed25519_publickey) (const ed25519_secret_key sk, ed25519_public_key pk) {
hash_512bits extsk = {0};
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ed25519_extsk(extsk, sk);
ed25519_publickey_ext(extsk, pk);
memzero(&extsk, sizeof(extsk));
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}
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void
ED25519_FN(ed25519_cosi_commit) (ed25519_secret_key nonce, ed25519_public_key commitment) {
bignum256modm r = {0};
ge25519 ALIGN(16) R;
unsigned char extnonce[64] = {0};
/* r = random512 mod L */
random_buffer(extnonce, sizeof(extnonce));
expand256_modm(r, extnonce, sizeof(extnonce));
memzero(&extnonce, sizeof(extnonce));
contract256_modm(nonce, r);
/* R = rB */
ge25519_scalarmult_base_wrapper(&R, r);
memzero(&r, sizeof(r));
ge25519_pack(commitment, &R);
}
int
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ED25519_FN(ed25519_cosi_sign) (const unsigned char *m, size_t mlen, const ed25519_secret_key sk, const ed25519_secret_key nonce, const ed25519_public_key R, const ed25519_public_key pk, ed25519_cosi_signature sig) {
bignum256modm r = {0}, S = {0}, a = {0};
hash_512bits extsk = {0}, hram = {0};
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ed25519_extsk(extsk, sk);
/* r */
expand_raw256_modm(r, nonce);
if (!is_reduced256_modm(r))
return -1;
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/* S = H(R,A,m).. */
ed25519_hram(hram, R, pk, m, mlen);
expand256_modm(S, hram, 64);
/* S = H(R,A,m)a */
expand256_modm(a, extsk, 32);
memzero(&extsk, sizeof(extsk));
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mul256_modm(S, S, a);
memzero(&a, sizeof(a));
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/* S = (r + H(R,A,m)a) */
add256_modm(S, S, r);
memzero(&r, sizeof(r));
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/* S = (r + H(R,A,m)a) mod L */
contract256_modm(sig, S);
return 0;
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}
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void
ED25519_FN(ed25519_sign_ext) (const unsigned char *m, size_t mlen, const ed25519_secret_key secret_scalar, const ed25519_secret_key skext, ed25519_signature RS) {
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ed25519_hash_context ctx;
bignum256modm r = {0}, S = {0}, a = {0};
ge25519 ALIGN(16) R = {0};
ge25519 ALIGN(16) A = {0};
ed25519_public_key pk = {0};
hash_512bits hashr = {0}, hram = {0};
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/* r = H(aExt[32..64], m) */
ed25519_hash_init(&ctx);
ed25519_hash_update(&ctx, skext, 32);
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ed25519_hash_update(&ctx, m, mlen);
ed25519_hash_final(&ctx, hashr);
expand256_modm(r, hashr, 64);
memzero(&hashr, sizeof(hashr));
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/* R = rB */
ge25519_scalarmult_base_wrapper(&R, r);
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ge25519_pack(RS, &R);
/* a = aExt[0..31] */
expand256_modm(a, secret_scalar, 32);
/* A = aB */
ge25519_scalarmult_base_wrapper(&A, a);
ge25519_pack(pk, &A);
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/* S = H(R,A,m).. */
ed25519_hram(hram, RS, pk, m, mlen);
expand256_modm(S, hram, 64);
/* S = H(R,A,m)a */
mul256_modm(S, S, a);
memzero(&a, sizeof(a));
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/* S = (r + H(R,A,m)a) */
add256_modm(S, S, r);
memzero(&r, sizeof(r));
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/* S = (r + H(R,A,m)a) mod L */
contract256_modm(RS + 32, S);
}
void
ED25519_FN(ed25519_sign) (const unsigned char *m, size_t mlen, const ed25519_secret_key sk, ed25519_signature RS) {
hash_512bits extsk = {0};
ed25519_extsk(extsk, sk);
ED25519_FN(ed25519_sign_ext)(m, mlen, extsk, extsk + 32, RS);
memzero(&extsk, sizeof(extsk));
}
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int
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ED25519_FN(ed25519_sign_open) (const unsigned char *m, size_t mlen, const ed25519_public_key pk, const ed25519_signature RS) {
ge25519 ALIGN(16) R = {0}, A = {0};
hash_512bits hash = {0};
bignum256modm hram = {0}, S = {0};
unsigned char checkR[32] = {0};
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if ((RS[63] & 224) || !ge25519_unpack_negative_vartime(&A, pk))
return -1;
/* hram = H(R,A,m) */
ed25519_hram(hash, RS, pk, m, mlen);
expand256_modm(hram, hash, 64);
/* S */
expand_raw256_modm(S, RS + 32);
if (!is_reduced256_modm(S))
return -1;
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/* SB - H(R,A,m)A */
ge25519_double_scalarmult_vartime(&R, &A, hram, S);
ge25519_pack(checkR, &R);
/* check that R = SB - H(R,A,m)A */
return ed25519_verify(RS, checkR, 32) ? 0 : -1;
}
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int
ED25519_FN(ed25519_scalarmult) (ed25519_public_key res, const ed25519_secret_key sk, const ed25519_public_key pk) {
bignum256modm a = {0};
ge25519 ALIGN(16) A = {0}, P = {0};
hash_512bits extsk = {0};
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ed25519_extsk(extsk, sk);
expand256_modm(a, extsk, 32);
memzero(&extsk, sizeof(extsk));
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if (!ge25519_unpack_negative_vartime(&P, pk)) {
return -1;
}
ge25519_scalarmult(&A, &P, a);
memzero(&a, sizeof(a));
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curve25519_neg(A.x, A.x);
ge25519_pack(res, &A);
return 0;
}
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#ifndef ED25519_SUFFIX
#include "curve25519-donna-scalarmult-base.h"
void
ed25519_publickey_ext(const ed25519_secret_key extsk, ed25519_public_key pk) {
bignum256modm a = {0};
ge25519 ALIGN(16) A = {0};
expand256_modm(a, extsk, 32);
/* A = aB */
ge25519_scalarmult_base_wrapper(&A, a);
memzero(&a, sizeof(a));
ge25519_pack(pk, &A);
}
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int
ed25519_cosi_combine_publickeys(ed25519_public_key res, CONST ed25519_public_key *pks, size_t n) {
size_t i = 0;
ge25519 P = {0};
ge25519_pniels sump = {0};
ge25519_p1p1 sump1 = {0};
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if (n == 1) {
memcpy(res, pks, sizeof(ed25519_public_key));
return 0;
}
if (!ge25519_unpack_negative_vartime(&P, pks[i++])) {
return -1;
}
ge25519_full_to_pniels(&sump, &P);
while (i < n - 1) {
if (!ge25519_unpack_negative_vartime(&P, pks[i++])) {
return -1;
}
ge25519_pnielsadd(&sump, &P, &sump);
}
if (!ge25519_unpack_negative_vartime(&P, pks[i++])) {
return -1;
}
ge25519_pnielsadd_p1p1(&sump1, &P, &sump, 0);
ge25519_p1p1_to_partial(&P, &sump1);
curve25519_neg(P.x, P.x);
ge25519_pack(res, &P);
return 0;
}
void
ed25519_cosi_combine_signatures(ed25519_signature res, const ed25519_public_key R, CONST ed25519_cosi_signature *sigs, size_t n) {
bignum256modm s = {0}, t = {0};
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size_t i = 0;
expand256_modm(s, sigs[i++], 32);
while (i < n) {
expand256_modm(t, sigs[i++], 32);
add256_modm(s, s, t);
}
memcpy(res, R, 32);
contract256_modm(res + 32, s);
}
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/*
Fast Curve25519 basepoint scalar multiplication
*/
void
curve25519_scalarmult_basepoint(curve25519_key pk, const curve25519_key e) {
curve25519_key ec = {0};
bignum256modm s = {0};
bignum25519 ALIGN(16) yplusz = {0}, zminusy = {0};
ge25519 ALIGN(16) p = {0};
size_t i = 0;
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/* clamp */
for (i = 0; i < 32; i++) ec[i] = e[i];
ec[0] &= 248;
ec[31] &= 127;
ec[31] |= 64;
expand_raw256_modm(s, ec);
memzero(&ec, sizeof(ec));
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/* scalar * basepoint */
ge25519_scalarmult_base_wrapper(&p, s);
memzero(&s, sizeof(s));
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/* u = (y + z) / (z - y) */
curve25519_add(yplusz, p.y, p.z);
curve25519_sub(zminusy, p.z, p.y);
curve25519_recip(zminusy, zminusy);
curve25519_mul(yplusz, yplusz, zminusy);
curve25519_contract(pk, yplusz);
}
void
curve25519_scalarmult(curve25519_key mypublic, const curve25519_key secret, const curve25519_key basepoint) {
curve25519_key e = {0};
size_t i = 0;
for (i = 0;i < 32;++i) e[i] = secret[i];
e[0] &= 0xf8;
e[31] &= 0x7f;
e[31] |= 0x40;
curve25519_scalarmult_donna(mypublic, e, basepoint);
memzero(&e, sizeof(e));
}
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#endif // ED25519_SUFFIX