/**
* Check whether if <b>signature</b> is a valid signature for the
* <b>len</b>-byte message in <b>msg</b> made with the key <b>pubkey</b>.
*
* Return 0 if the signature is valid; -1 if it isn't.
*/
int
ed25519_checksig(const ed25519_signature_t *signature,
const uint8_t *msg, size_t len,
const ed25519_public_key_t *pubkey)
{
return
get_ed_impl()->open(signature->sig, msg, len, pubkey->pubkey) < 0 ? -1 : 0;
}
/**
* Given an ed25519 public key in <b>inp</b>, generate a corresponding blinded
* public key in <b>out</b>, blinded with the 32-byte parameter in
* <b>param</b>. Return 0 on sucess, -1 on railure.
*/
int
ed25519_public_blind(ed25519_public_key_t *out,
const ed25519_public_key_t *inp,
const uint8_t *param)
{
get_ed_impl()->blind_public_key(out->pubkey, inp->pubkey, param);
return 0;
}
/**
* Given a secret key in <b>seckey</b>, expand it into an
* ed25519 public key. Return 0 on success, -1 on failure.
*/
int
ed25519_public_key_generate(ed25519_public_key_t *pubkey_out,
const ed25519_secret_key_t *seckey)
{
if (get_ed_impl()->pubkey(pubkey_out->pubkey, seckey->seckey) < 0)
return -1;
return 0;
}
/**
* Given a 32-byte random seed in <b>seed</b>, expand it into an ed25519
* secret key in <b>seckey_out</b>. Return 0 on success, -1 on failure.
*/
int
ed25519_secret_key_from_seed(ed25519_secret_key_t *seckey_out,
const uint8_t *seed)
{
if (get_ed_impl()->seckey_expand(seckey_out->seckey, seed) < 0)
return -1;
return 0;
}
/**
* Given a curve25519 public key and sign bit of X coordinate of the ed25519
* public key, generate the corresponding ed25519 public key.
*/
int
ed25519_public_key_from_curve25519_public_key(ed25519_public_key_t *pubkey,
const curve25519_public_key_t *pubkey_in,
int signbit)
{
return get_ed_impl()->pubkey_from_curve25519_pubkey(pubkey->pubkey,
pubkey_in->public_key,
signbit);
}
/**
* Set <b>signature_out</b> to a signature of the <b>len</b>-byte message
* <b>msg</b>, using the secret and public key in <b>keypair</b>.
*/
int
ed25519_sign(ed25519_signature_t *signature_out,
const uint8_t *msg, size_t len,
const ed25519_keypair_t *keypair)
{
if (get_ed_impl()->sign(signature_out->sig, msg, len,
keypair->seckey.seckey,
keypair->pubkey.pubkey) < 0) {
return -1;
}
return 0;
}
/**
* Initialize a new ed25519 secret key in <b>seckey_out</b>. If
* <b>extra_strong</b>, take the RNG inputs directly from the operating
* system. Return 0 on success, -1 on failure.
*/
int
ed25519_secret_key_generate(ed25519_secret_key_t *seckey_out,
int extra_strong)
{
int r;
uint8_t seed[32];
if (! extra_strong || crypto_strongest_rand(seed, sizeof(seed)) < 0)
crypto_rand((char*)seed, sizeof(seed));
r = get_ed_impl()->seckey_expand(seckey_out->seckey, seed);
memwipe(seed, 0, sizeof(seed));
return r < 0 ? -1 : 0;
}
/**
* Given an ed25519 keypair in <b>inp</b>, generate a corresponding
* ed25519 keypair in <b>out</b>, blinded by the corresponding 32-byte input
* in 'param'.
*
* Tor uses key blinding for the "next-generation" hidden services design:
* service descriptors are encrypted with a key derived from the service's
* long-term public key, and then signed with (and stored at a position
* indexed by) a short-term key derived by blinding the long-term keys.
*/
int
ed25519_keypair_blind(ed25519_keypair_t *out,
const ed25519_keypair_t *inp,
const uint8_t *param)
{
ed25519_public_key_t pubkey_check;
get_ed_impl()->blind_secret_key(out->seckey.seckey,
inp->seckey.seckey, param);
ed25519_public_blind(&pubkey_check, &inp->pubkey, param);
ed25519_public_key_generate(&out->pubkey, &out->seckey);
tor_assert(fast_memeq(pubkey_check.pubkey, out->pubkey.pubkey, 32));
memwipe(&pubkey_check, 0, sizeof(pubkey_check));
return 0;
}
/** Check whether the given Ed25519 implementation seems to be working.
* If so, return 0; otherwise return -1. */
static int
ed25519_impl_spot_check(void)
{
static const uint8_t alicesk[32] = {
0xc5,0xaa,0x8d,0xf4,0x3f,0x9f,0x83,0x7b,
0xed,0xb7,0x44,0x2f,0x31,0xdc,0xb7,0xb1,
0x66,0xd3,0x85,0x35,0x07,0x6f,0x09,0x4b,
0x85,0xce,0x3a,0x2e,0x0b,0x44,0x58,0xf7
};
static const uint8_t alicepk[32] = {
0xfc,0x51,0xcd,0x8e,0x62,0x18,0xa1,0xa3,
0x8d,0xa4,0x7e,0xd0,0x02,0x30,0xf0,0x58,
0x08,0x16,0xed,0x13,0xba,0x33,0x03,0xac,
0x5d,0xeb,0x91,0x15,0x48,0x90,0x80,0x25
};
static const uint8_t alicemsg[2] = { 0xaf, 0x82 };
static const uint8_t alicesig[64] = {
0x62,0x91,0xd6,0x57,0xde,0xec,0x24,0x02,
0x48,0x27,0xe6,0x9c,0x3a,0xbe,0x01,0xa3,
0x0c,0xe5,0x48,0xa2,0x84,0x74,0x3a,0x44,
0x5e,0x36,0x80,0xd7,0xdb,0x5a,0xc3,0xac,
0x18,0xff,0x9b,0x53,0x8d,0x16,0xf2,0x90,
0xae,0x67,0xf7,0x60,0x98,0x4d,0xc6,0x59,
0x4a,0x7c,0x15,0xe9,0x71,0x6e,0xd2,0x8d,
0xc0,0x27,0xbe,0xce,0xea,0x1e,0xc4,0x0a
};
const ed25519_impl_t *impl = get_ed_impl();
uint8_t sk[ED25519_SECKEY_LEN];
uint8_t pk[ED25519_PUBKEY_LEN];
uint8_t sig[ED25519_SIG_LEN];
int r = 0;
/* Some implementations (eg: The modified Ed25519-donna) have handy self-test
* code that sanity-checks the internals. If present, use that to screen out
* catastrophic errors like massive compiler failure.
*/
if (impl->selftest && impl->selftest() != 0)
goto fail;
/* Validate results versus known answer tests. People really should be
* running "make test" instead of relying on this, but it's better than
* nothing.
*
* Test vectors taken from "EdDSA & Ed25519 - 6. Test Vectors for Ed25519
* (TEST3)" (draft-josefsson-eddsa-ed25519-03).
*/
/* Key expansion, public key derivation. */
if (impl->seckey_expand(sk, alicesk) < 0)
goto fail;
if (impl->pubkey(pk, sk) < 0)
goto fail;
if (fast_memneq(pk, alicepk, ED25519_PUBKEY_LEN))
goto fail;
/* Signing, verification. */
if (impl->sign(sig, alicemsg, sizeof(alicemsg), sk, pk) < 0)
return -1;
if (fast_memneq(sig, alicesig, ED25519_SIG_LEN))
return -1;
if (impl->open(sig, alicemsg, sizeof(alicemsg), pk) < 0)
return -1;
/* XXX/yawning: Someone that's more paranoid than I am, can write "Assume
* ref0 is cannonical, and fuzz impl against it" if they want, but I doubt
* that will catch anything that the known answer tests won't.
*/
goto end;
fail:
r = -1;
end:
return r;
}
/** Validate every signature among those in <b>checkable</b>, which contains
* exactly <b>n_checkable</b> elements. If <b>okay_out</b> is non-NULL, set
* the i'th element of <b>okay_out</b> to 1 if the i'th element of
* <b>checkable</b> is valid, and to 0 otherwise. Return 0 if every signature
* was valid. Otherwise return -N, where N is the number of invalid
* signatures.
*/
int
ed25519_checksig_batch(int *okay_out,
const ed25519_checkable_t *checkable,
int n_checkable)
{
int i, res;
const ed25519_impl_t *impl = get_ed_impl();
if (impl->open_batch == NULL) {
/* No batch verification implementation available, fake it by checking the
* each signature individually.
*/
res = 0;
for (i = 0; i < n_checkable; ++i) {
const ed25519_checkable_t *ch = &checkable[i];
int r = ed25519_checksig(&ch->signature, ch->msg, ch->len, ch->pubkey);
if (r < 0)
--res;
if (okay_out)
okay_out[i] = (r == 0);
}
} else {
/* ed25519-donna style batch verification available.
*
* Theoretically, this should only be called if n_checkable >= 3, since
* that's the threshold where the batch verification actually kicks in,
* but the only difference is a few mallocs/frees.
*/
const uint8_t **ms;
size_t *lens;
const uint8_t **pks;
const uint8_t **sigs;
int *oks;
int all_ok;
ms = tor_malloc(sizeof(uint8_t*)*n_checkable);
lens = tor_malloc(sizeof(size_t)*n_checkable);
pks = tor_malloc(sizeof(uint8_t*)*n_checkable);
sigs = tor_malloc(sizeof(uint8_t*)*n_checkable);
oks = okay_out ? okay_out : tor_malloc(sizeof(int)*n_checkable);
for (i = 0; i < n_checkable; ++i) {
ms[i] = checkable[i].msg;
lens[i] = checkable[i].len;
pks[i] = checkable[i].pubkey->pubkey;
sigs[i] = checkable[i].signature.sig;
oks[i] = 0;
}
res = 0;
all_ok = impl->open_batch(ms, lens, pks, sigs, n_checkable, oks);
for (i = 0; i < n_checkable; ++i) {
if (!oks[i])
--res;
}
/* XXX: For now sanity check oks with the return value. Once we have
* more confidence in the code, if `all_ok == 0` we can skip iterating
* over oks since all the signatures were found to be valid.
*/
tor_assert(((res == 0) && !all_ok) || ((res < 0) && all_ok));
tor_free(ms);
tor_free(lens);
tor_free(pks);
tor_free(sigs);
if (! okay_out)
tor_free(oks);
}
return res;
}
