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Diffstat (limited to 'src/ext/ed25519/donna/ed25519.c')
| -rw-r--r-- | src/ext/ed25519/donna/ed25519.c | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/src/ext/ed25519/donna/ed25519.c b/src/ext/ed25519/donna/ed25519.c new file mode 100644 index 0000000000..58a755b8d3 --- /dev/null +++ b/src/ext/ed25519/donna/ed25519.c @@ -0,0 +1,150 @@ +/* + Public domain by Andrew M. <liquidsun@gmail.com> + + Ed25519 reference implementation using Ed25519-donna +*/ + + +/* define ED25519_SUFFIX to have it appended to the end of each public function */ +#if !defined(ED25519_SUFFIX) +#define ED25519_SUFFIX +#endif + +#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) + +#include "ed25519-donna.h" +#include "ed25519.h" +#include "ed25519-randombytes.h" +#include "ed25519-hash.h" + +/* + 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_signature RS, const ed25519_public_key pk, const unsigned char *m, size_t mlen) { + ed25519_hash_context ctx; + ed25519_hash_init(&ctx); + ed25519_hash_update(&ctx, RS, 32); + ed25519_hash_update(&ctx, pk, 32); + ed25519_hash_update(&ctx, m, mlen); + ed25519_hash_final(&ctx, hram); +} + +void +ED25519_FN(ed25519_publickey) (const ed25519_secret_key sk, ed25519_public_key pk) { + bignum256modm a; + ge25519 ALIGN(16) A; + hash_512bits extsk; + + /* A = aB */ + ed25519_extsk(extsk, sk); + expand256_modm(a, extsk, 32); + ge25519_scalarmult_base_niels(&A, ge25519_niels_base_multiples, a); + ge25519_pack(pk, &A); +} + + +void +ED25519_FN(ed25519_sign) (const unsigned char *m, size_t mlen, const ed25519_secret_key sk, const ed25519_public_key pk, ed25519_signature RS) { + ed25519_hash_context ctx; + bignum256modm r, S, a; + ge25519 ALIGN(16) R; + hash_512bits extsk, hashr, hram; + + ed25519_extsk(extsk, sk); + + /* r = H(aExt[32..64], m) */ + ed25519_hash_init(&ctx); + ed25519_hash_update(&ctx, extsk + 32, 32); + ed25519_hash_update(&ctx, m, mlen); + ed25519_hash_final(&ctx, hashr); + expand256_modm(r, hashr, 64); + + /* R = rB */ + ge25519_scalarmult_base_niels(&R, ge25519_niels_base_multiples, r); + ge25519_pack(RS, &R); + + /* S = H(R,A,m).. */ + ed25519_hram(hram, RS, pk, m, mlen); + expand256_modm(S, hram, 64); + + /* S = H(R,A,m)a */ + expand256_modm(a, extsk, 32); + mul256_modm(S, S, a); + + /* S = (r + H(R,A,m)a) */ + add256_modm(S, S, r); + + /* S = (r + H(R,A,m)a) mod L */ + contract256_modm(RS + 32, S); +} + +int +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, A; + hash_512bits hash; + bignum256modm hram, S; + unsigned char checkR[32]; + + 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 */ + expand256_modm(S, RS + 32, 32); + + /* 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; +} + +#include "ed25519-donna-batchverify.h" + +/* + Fast Curve25519 basepoint scalar multiplication +*/ + +void +ED25519_FN(curved25519_scalarmult_basepoint) (curved25519_key pk, const curved25519_key e) { + curved25519_key ec; + bignum256modm s; + bignum25519 ALIGN(16) yplusz, zminusy; + ge25519 ALIGN(16) p; + size_t i; + + /* 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); + + /* scalar * basepoint */ + ge25519_scalarmult_base_niels(&p, ge25519_niels_base_multiples, s); + + /* 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); +} + |