// our SHA is SHA-256
#define SHA_DIGESTSIZE 32
-const char *sha(const char *in, size_t len)
+const char *sha(const unsigned char *in, size_t len)
{
static char h[32];
- d0_blind_id_util_sha256(h, in, len);
+ d0_blind_id_util_sha256(h, (const char *) in, len);
return h;
}
return 0;
}
-D0_WARN_UNUSED_RESULT D0_BOOL d0_longhash_destructive(d0_bignum_t *clobberme, char *outbuf, size_t outbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_longhash_destructive(unsigned char *convbuf, size_t sz, unsigned char *outbuf, size_t outbuflen)
{
- d0_iobuf_t *out = NULL;
- static unsigned char convbuf[1024];
- size_t n, sz;
+ size_t n, i;
n = outbuflen;
while(n > SHA_DIGESTSIZE)
{
- sz = (d0_bignum_size(clobberme) + 7) / 8;
- CHECK(d0_bignum_export_unsigned(clobberme, convbuf, sizeof(convbuf)) >= 0);
memcpy(outbuf, sha(convbuf, sz), SHA_DIGESTSIZE);
outbuf += SHA_DIGESTSIZE;
n -= SHA_DIGESTSIZE;
- CHECK(d0_bignum_add(clobberme, clobberme, one));
+ for(i = 0; i < sz; ++i)
+ if(++convbuf[i])
+ break; // stop until no carry
}
- sz = (d0_bignum_size(clobberme) + 7) / 8;
- CHECK(d0_bignum_export_unsigned(clobberme, convbuf, sizeof(convbuf)) >= 0);
memcpy(outbuf, sha(convbuf, sz), n);
return 1;
+}
+
+D0_WARN_UNUSED_RESULT D0_BOOL d0_longhash_bignum(const d0_bignum_t *in, unsigned char *outbuf, size_t outbuflen)
+{
+ static unsigned char convbuf[1024];
+ size_t sz;
+
+ CHECK(d0_bignum_export_unsigned(in, convbuf, sizeof(convbuf)) >= 0);
+ sz = (d0_bignum_size(in) + 7) / 8;
+ CHECK(d0_longhash_destructive(convbuf, sz, outbuf, outbuflen));
+ return 1;
fail:
return 0;
D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
{
d0_iobuf_t *out = NULL;
- static unsigned char convbuf[2048], shabuf[2048];
+ static unsigned char shabuf[2048];
size_t sz;
// temps: temp0 rsa_blind_signature_camouflage^challenge, temp1 (4^s)*rsa_blind_signature_camouflage^challenge
sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
if(sz > sizeof(shabuf))
sz = sizeof(shabuf);
- CHECK(d0_longhash_destructive(temp2, shabuf, sz));
+ CHECK(d0_longhash_bignum(temp2, shabuf, sz));
CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
// hash complete
return 0;
}
-D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_authenticate_with_private_id_start(d0_blind_id_t *ctx, D0_BOOL is_first, D0_BOOL send_modulus, char *msg, size_t msglen, char *outbuf, size_t *outbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_authenticate_with_private_id_start(d0_blind_id_t *ctx, D0_BOOL is_first, D0_BOOL send_modulus, const char *msg, size_t msglen, char *outbuf, size_t *outbuflen)
// start =
// first run: send 4^s, 4^s signature
// 1. get random r, send HASH(4^r)
CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp0));
// can we SOMEHOW do this with just one mod_pow?
- MPCHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
- MPCHECK_ASSIGN(ctx->g_to_t, d0_bignum_mod_pow(ctx->g_to_t, four, ctx->t, ctx->schnorr_G));
+ CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
+ CHECK_ASSIGN(ctx->g_to_t, d0_bignum_mod_pow(ctx->g_to_t, four, ctx->t, ctx->schnorr_G));
CHECK(!failed);
// hash it, hash it, everybody hash it
sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
if(sz > sizeof(shabuf))
sz = sizeof(shabuf);
- CHECK(d0_longhash_destructive(temp2, shabuf, sz));
+ CHECK(d0_longhash_bignum(temp2, shabuf, sz));
CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
// + 7 / 8 is too large, so let's mod it
sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
if(sz > sizeof(shabuf))
sz = sizeof(shabuf);
- CHECK(d0_longhash_destructive(temp2, shabuf, sz));
+ CHECK(d0_longhash_bignum(temp2, shabuf, sz));
CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
// + 7 / 8 is too large, so let's mod it
return 0;
}
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_sign_with_private_id_sign(d0_blind_id_t *ctx, D0_BOOL is_first, D0_BOOL send_modulus, const char *message, size_t msglen, char *outbuf, size_t *outbuflen)
+{
+ d0_iobuf_t *out = NULL;
+ static unsigned char convbuf[1024];
+ static unsigned char shabuf[1024];
+ d0_iobuf_t *conv = NULL;
+ size_t sz = 0;
+
+ if(is_first)
+ {
+ USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
+ }
+ USING(schnorr_G);
+ USING(schnorr_s);
+ REPLACING(r);
+
+ out = d0_iobuf_open_write(outbuf, *outbuflen);
+
+ if(is_first)
+ {
+ // send ID
+ if(send_modulus)
+ CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
+ CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
+ CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
+ }
+
+ // start schnorr SIGNATURE scheme
+ // generate random number r; x = g^r; send hash of H(m||r), remember r, forget x
+ CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
+ CHECK_ASSIGN(ctx->r, d0_bignum_rand_range(ctx->r, zero, temp0));
+ CHECK(d0_bignum_mod_pow(temp1, four, ctx->r, ctx->schnorr_G));
+
+ // hash it, hash it, everybody hash it
+ conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
+ CHECK(d0_iobuf_write_packet(conv, message, msglen));
+ CHECK(d0_iobuf_write_bignum(conv, temp1));
+ d0_iobuf_close(conv, &sz);
+ conv = NULL;
+ CHECK(d0_longhash_destructive(convbuf, sz, shabuf, (d0_bignum_size(temp0) + 7) / 8));
+ CHECK(d0_bignum_import_unsigned(temp2, shabuf, (d0_bignum_size(temp0) + 7) / 8));
+ CHECK(d0_iobuf_write_bignum(out, temp2));
+
+ // multiply with secret, sub k, modulo order
+ CHECK(d0_bignum_mod_mul(temp1, temp2, ctx->schnorr_s, temp0));
+ CHECK(d0_bignum_mod_sub(temp2, ctx->r, temp1, temp0));
+ CHECK(d0_iobuf_write_bignum(out, temp2));
+
+ // write the message itself
+ CHECK(d0_iobuf_write_packet(out, message, msglen));
+
+ return d0_iobuf_close(out, outbuflen);
+
+fail:
+ d0_iobuf_close(out, outbuflen);
+ return 0;
+}
+
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_sign_with_private_id_verify(d0_blind_id_t *ctx, D0_BOOL is_first, D0_BOOL recv_modulus, const char *inbuf, size_t inbuflen, char *msg, size_t *msglen, D0_BOOL *status)
+{
+ d0_iobuf_t *in = NULL;
+ d0_iobuf_t *conv = NULL;
+ static unsigned char convbuf[2048];
+ static unsigned char shabuf[2048];
+ size_t sz;
+
+ if(is_first)
+ {
+ REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
+ if(recv_modulus)
+ REPLACING(schnorr_G);
+ else
+ USING(schnorr_G);
+ }
+ else
+ {
+ USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
+ USING(schnorr_G);
+ }
+ USING(rsa_e); USING(rsa_n);
+
+ in = d0_iobuf_open_read(inbuf, inbuflen);
+
+ if(is_first)
+ {
+ if(recv_modulus)
+ {
+ CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
+ CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
+ CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
+ }
+ CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
+ CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, zero) >= 0);
+ CHECK(d0_bignum_cmp(ctx->schnorr_g_to_s, ctx->schnorr_G) < 0);
+ CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
+ CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero) >= 0);
+ CHECK(d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, ctx->rsa_n) < 0);
+
+ // check signature of key (t = k^d, so, t^challenge = k)
+ CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_H_g_to_s_signature, ctx->rsa_e, ctx->rsa_n));
+
+ // we will actually sign SHA(4^s) to prevent a malleability attack!
+ CHECK(d0_bignum_mov(temp2, ctx->schnorr_g_to_s));
+ sz = (d0_bignum_size(ctx->rsa_n) + 7) / 8; // this is too long, so we have to take the value % rsa_n when "decrypting"
+ if(sz > sizeof(shabuf))
+ sz = sizeof(shabuf);
+ CHECK(d0_longhash_bignum(temp2, shabuf, sz));
+ CHECK(d0_bignum_import_unsigned(temp2, shabuf, sz));
+
+ // + 7 / 8 is too large, so let's mod it
+ CHECK(d0_bignum_divmod(NULL, temp1, temp2, ctx->rsa_n));
+
+ // hash complete
+ if(d0_bignum_cmp(temp0, temp1))
+ {
+ // accept the key anyway, but mark as failed signature! will later return 0 in status
+ CHECK(d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
+ }
+ }
+
+ CHECK(d0_dl_get_order(temp4, ctx->schnorr_G));
+ CHECK(d0_iobuf_read_bignum(in, temp0)); // e == H(m || g^r)
+ CHECK(d0_iobuf_read_bignum(in, temp1)); // x == (r - s*e) mod |G|
+ CHECK(d0_iobuf_read_packet(in, msg, msglen));
+
+ // VERIFY: g^x * (g^s)^-e = g^(x - s*e) = g^r
+
+ // verify schnorr ID scheme
+ // we need g^r = g^x (g^s)^e
+ CHECK(d0_bignum_mod_pow(temp2, four, temp1, ctx->schnorr_G));
+ CHECK(d0_bignum_mod_pow(temp1, ctx->schnorr_g_to_s, temp0, ctx->schnorr_G));
+ CHECK_ASSIGN(temp3, d0_bignum_mod_mul(temp3, temp1, temp2, ctx->schnorr_G)); // temp3 now is g^r
+
+ // hash it, hash it, everybody hash it
+ conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
+ CHECK(d0_iobuf_write_packet(conv, msg, *msglen));
+ CHECK(d0_iobuf_write_bignum(conv, temp3));
+ d0_iobuf_close(conv, &sz);
+ conv = NULL;
+ CHECK(d0_longhash_destructive(convbuf, sz, shabuf, (d0_bignum_size(temp4) + 7) / 8));
+ CHECK(d0_bignum_import_unsigned(temp1, shabuf, (d0_bignum_size(temp4) + 7) / 8));
+
+ // verify signature
+ CHECK(!d0_bignum_cmp(temp0, temp1));
+
+ if(status)
+ *status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
+
+ d0_iobuf_close(in, NULL);
+ return 1;
+
+fail:
+ d0_iobuf_close(in, NULL);
+ return 0;
+}
+
D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_fingerprint64_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
{
d0_iobuf_t *out = NULL;
// temps: temp0 result
CHECK(d0_bignum_mod_pow(temp0, ctx->other_g_to_t, ctx->t, ctx->schnorr_G));
- return d0_longhash_destructive(temp0, outbuf, *outbuflen);
+ return d0_longhash_bignum(temp0, (unsigned char *) outbuf, *outbuflen);
fail:
return 0;
projects / xonotic / d0_blind_id.git / commitdiff