X-Git-Url: http://de.git.xonotic.org/?a=blobdiff_plain;f=d0_blind_id.c;h=e138642c240a7d490a76ee722b68a779c125cf67;hb=503ed535983a12b4333428712ac404d062519782;hp=cc85624e5cc8e680f8251dc09da0366135e81496;hpb=4145420d34f05696e610e2f414874312ad572479;p=xonotic%2Fd0_blind_id.git

diff --git a/d0_blind_id.c b/d0_blind_id.c
index cc85624..e138642 100644
--- a/d0_blind_id.c
+++ b/d0_blind_id.c
@@ -88,9 +88,9 @@ struct d0_blind_id_s
 
 static d0_bignum_t *zero, *one, *four, *temp0, *temp1, *temp2, *temp3, *temp4;
 
-void d0_blind_id_INITIALIZE(void)
+WARN_UNUSED_RESULT BOOL d0_blind_id_INITIALIZE(void)
 {
-	d0_bignum_INITIALIZE();
+	CHECK(d0_bignum_INITIALIZE());
 	CHECK_ASSIGN(zero, d0_bignum_int(zero, 0));
 	CHECK_ASSIGN(one, d0_bignum_int(one, 1));
 	CHECK_ASSIGN(four, d0_bignum_int(four, 4));
@@ -99,8 +99,9 @@ void d0_blind_id_INITIALIZE(void)
 	CHECK_ASSIGN(temp2, d0_bignum_int(temp2, 0));
 	CHECK_ASSIGN(temp3, d0_bignum_int(temp3, 0));
 	CHECK_ASSIGN(temp4, d0_bignum_int(temp4, 0));
+	return 1;
 fail:
-	;
+	return 0;
 }
 
 void d0_blind_id_SHUTDOWN(void)
@@ -979,6 +980,31 @@ fail:
 	return 0;
 }
 
+WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_generate_missing_signature(d0_blind_id_t *ctx)
+{
+	size_t sz;
+	static unsigned char shabuf[2048];
+
+	REPLACING(schnorr_H_g_to_s_signature);
+	USING(schnorr_g_to_s); USING(rsa_d); USING(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_destructive(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));
+	CHECK(d0_bignum_mod_pow(ctx->schnorr_H_g_to_s_signature, temp1, ctx->rsa_d, ctx->rsa_n));
+	return 1;
+
+fail:
+	return 0;
+}
+
 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
 {
 	d0_iobuf_t *out = NULL;