X-Git-Url: https://git.xonotic.org/?a=blobdiff_plain;f=d0_blind_id.c;h=9bb650c7b9dae4b6a84f7f20039cbe7ec5cc4d05;hb=362e75067dede2446444e86a9d6384fc8fe83a38;hp=673245525f1211f41a21a143656a0d0609b71d14;hpb=96974f716a500bab3fc813644021e706331a94d9;p=xonotic%2Fd0_blind_id.git

diff --git a/d0_blind_id.c b/d0_blind_id.c
index 6732455..9bb650c 100644
--- a/d0_blind_id.c
+++ b/d0_blind_id.c
@@ -1,28 +1,53 @@
 /*
-Blind-ID library for user identification using RSA blind signatures
-Copyright (C) 2010  Rudolf Polzer
-
-This library is free software; you can redistribute it and/or
-modify it under the terms of the GNU Lesser General Public
-License as published by the Free Software Foundation; either
-version 2.1 of the License, or (at your option) any later version.
-
-This library is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-Lesser General Public License for more details.
-
-You should have received a copy of the GNU Lesser General Public
-License along with this library; if not, write to the Free Software
-Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-*/
+ * FILE:	d0_blind_id.c
+ * AUTHOR:	Rudolf Polzer - divVerent@xonotic.org
+ * 
+ * Copyright (c) 2010, Rudolf Polzer
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTOR(S) ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTOR(S) BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $Format:commit %H$
+ * $Id$
+ */
 
 #include "d0_blind_id.h"
 
 #include <stdio.h>
 #include <string.h>
 #include "d0_bignum.h"
-#include "sha1.h"
+#include "sha2.h"
+
+// our SHA is SHA-256
+#define SHA_DIGESTSIZE 32
+const char *sha(const char *in, size_t len)
+{
+	static char h[32];
+	d0_blind_id_util_sha256(h, in, len);
+	return h;
+}
 
 // for zero knowledge, we need multiple instances of schnorr ID scheme... should normally be sequential
 // parallel schnorr ID is not provably zero knowledge :(
@@ -32,9 +57,10 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 #define SCHNORR_BITS 20
 // probability of cheat: 2^(-bits+1)
 
-#define SCHNORR_HASHSIZE 3
-// cannot be >= SHA_DIGEST_LENGTH
+#define SCHNORR_HASHSIZE SHA_DIGESTSIZE
+// cannot be >= SHA_DIGESTSIZE
 // *8 must be >= SCHNORR_BITS
+// no need to save bits here
 
 #define MSGSIZE 640 // ought to be enough for anyone
 
@@ -50,26 +76,37 @@ struct d0_blind_id_s
 	d0_bignum_t *schnorr_s;
 
 	// public data (player ID public key, this is what the server gets to know)
-	d0_bignum_t *schnorr_4_to_s;
-	d0_bignum_t *schnorr_4_to_s_signature; // 0 when signature is invalid
+	d0_bignum_t *schnorr_g_to_s;
+	d0_bignum_t *schnorr_H_g_to_s_signature; // 0 when signature is invalid
+	// as hash function H, we get the SHA1 and reinterpret as bignum - yes, it always is < 160 bits
 
 	// temp data
-	d0_bignum_t *rn; // random number blind signature
+	d0_bignum_t *rsa_blind_signature_camouflage; // random number blind signature
+
 	d0_bignum_t *r; // random number for schnorr ID
-	char xnbh[SCHNORR_HASHSIZE]; // init hash
-	d0_bignum_t *e; // challenge
+	d0_bignum_t *t; // for DH key exchange
+	d0_bignum_t *g_to_t; // for DH key exchange
+	d0_bignum_t *other_g_to_t; // for DH key exchange
+	d0_bignum_t *challenge; // challenge
+
+	char msghash[SCHNORR_HASHSIZE]; // init hash
 	char msg[MSGSIZE]; // message
 	size_t msglen; // message length
 };
 
 #define CHECK(x) do { if(!(x)) goto fail; } while(0)
 #define CHECK_ASSIGN(var, value) do { d0_bignum_t *val; val = value; if(!val) goto fail; var = val; } while(0)
+#define MPCHECK(x) do { if(!failed) if(!(x)) failed = 1; } while(0)
+#define MPCHECK_ASSIGN(var, value) do { if(!failed) { d0_bignum_t *val; val = value; if(val) var = val; else failed = 1; } } while(0)
+
+#define USING(x) if(!(ctx->x)) return 0
+#define REPLACING(x)
 
 static d0_bignum_t *zero, *one, *four, *temp0, *temp1, *temp2, *temp3, *temp4;
 
-void d0_blind_id_INITIALIZE(void)
+D0_WARN_UNUSED_RESULT D0_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));
@@ -78,8 +115,9 @@ 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)
@@ -114,7 +152,7 @@ fail:
 	return NULL;
 }
 
-BOOL d0_dl_generate_key(size_t size, d0_bignum_t *G)
+D0_BOOL d0_dl_generate_key(size_t size, d0_bignum_t *G)
 {
 	// using: temp0
 	if(size < 16)
@@ -136,7 +174,7 @@ fail:
 	return 0;
 }
 
-BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *e, d0_bignum_t *d, d0_bignum_t *n)
+D0_BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *challenge, d0_bignum_t *d, d0_bignum_t *n)
 {
 	// uses temp0 to temp4
 	int fail = 0;
@@ -153,7 +191,7 @@ BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *e, d0_bignum_t *d, d0_b
 		if(d0_bignum_isprime(temp0, 10) == 0)
 			continue;
 		CHECK(d0_bignum_sub(temp2, temp0, one));
-		CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, e));
+		CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, challenge));
 		if(!d0_bignum_cmp(temp4, one))
 			break;
 		if(++gcdfail == 3)
@@ -173,7 +211,7 @@ BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *e, d0_bignum_t *d, d0_b
 		if(d0_bignum_isprime(temp1, 10) == 0)
 			continue;
 		CHECK(d0_bignum_sub(temp3, temp1, one));
-		CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, e));
+		CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, challenge));
 		if(!d0_bignum_cmp(temp4, one))
 			break;
 		if(++gcdfail == 3)
@@ -183,15 +221,99 @@ BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *e, d0_bignum_t *d, d0_b
 
 	// n = temp0*temp1
 	CHECK(d0_bignum_mul(n, temp0, temp1));
-		
-	// d = e^-1 mod (temp0-1)(temp1-1)
+
+	// d = challenge^-1 mod (temp0-1)(temp1-1)
 	CHECK(d0_bignum_mul(temp0, temp2, temp3));
-	CHECK(d0_bignum_mod_inv(d, e, temp0));
+	CHECK(d0_bignum_mod_inv(d, challenge, temp0));
 	return 1;
 fail:
 	return 0;
 }
 
+D0_BOOL d0_rsa_generate_key_fastreject(size_t size, d0_fastreject_function reject, d0_blind_id_t *ctx, void *pass)
+{
+	// uses temp0 to temp4
+	int fail = 0;
+	int gcdfail = 0;
+	int pb = (size + 1)/2;
+	int qb = size - pb;
+	if(pb < 8)
+		pb = 8;
+	if(qb < 8)
+		qb = 8;
+        for (;;)
+	{
+		CHECK(d0_bignum_rand_bit_exact(temp0, pb));
+		if(d0_bignum_isprime(temp0, 10) == 0)
+			continue;
+		CHECK(d0_bignum_sub(temp2, temp0, one));
+		CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp2, ctx->rsa_e));
+		if(!d0_bignum_cmp(temp4, one))
+			break;
+		if(++gcdfail == 3)
+			return 0;
+		++gcdfail;
+	}
+	gcdfail = 0;
+        for (;;)
+	{
+		CHECK(d0_bignum_rand_bit_exact(temp1, qb));
+		if(!d0_bignum_cmp(temp1, temp0))
+		{
+			if(++fail == 3)
+				return 0;
+		}
+		fail = 0;
+
+		// n = temp0*temp1
+		CHECK(d0_bignum_mul(ctx->rsa_n, temp0, temp1));
+		if(reject(ctx, pass))
+			continue;
+
+		if(d0_bignum_isprime(temp1, 10) == 0)
+			continue;
+		CHECK(d0_bignum_sub(temp3, temp1, one));
+		CHECK(d0_bignum_gcd(temp4, NULL, NULL, temp3, ctx->rsa_e));
+		if(!d0_bignum_cmp(temp4, one))
+			break;
+		if(++gcdfail == 3)
+			return 0;
+		++gcdfail;
+	}
+
+	// ctx->rsa_d = ctx->rsa_e^-1 mod (temp0-1)(temp1-1)
+	CHECK(d0_bignum_mul(temp0, temp2, temp3));
+	CHECK(d0_bignum_mod_inv(ctx->rsa_d, ctx->rsa_e, temp0));
+	return 1;
+fail:
+	return 0;
+}
+
+D0_WARN_UNUSED_RESULT D0_BOOL d0_longhash_destructive(d0_bignum_t *clobberme, char *outbuf, size_t outbuflen)
+{
+	d0_iobuf_t *out = NULL;
+	static unsigned char convbuf[1024];
+	size_t n, sz;
+
+	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));
+	}
+	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;
+
+fail:
+	return 0;
+}
+
 void d0_blind_id_clear(d0_blind_id_t *ctx)
 {
 	if(ctx->rsa_n) d0_bignum_free(ctx->rsa_n);
@@ -199,45 +321,71 @@ void d0_blind_id_clear(d0_blind_id_t *ctx)
 	if(ctx->rsa_d) d0_bignum_free(ctx->rsa_d);
 	if(ctx->schnorr_G) d0_bignum_free(ctx->schnorr_G);
 	if(ctx->schnorr_s) d0_bignum_free(ctx->schnorr_s);
-	if(ctx->schnorr_4_to_s) d0_bignum_free(ctx->schnorr_4_to_s);
-	if(ctx->schnorr_4_to_s_signature) d0_bignum_free(ctx->schnorr_4_to_s_signature);
-	if(ctx->rn) d0_bignum_free(ctx->rn);
+	if(ctx->schnorr_g_to_s) d0_bignum_free(ctx->schnorr_g_to_s);
+	if(ctx->schnorr_H_g_to_s_signature) d0_bignum_free(ctx->schnorr_H_g_to_s_signature);
+	if(ctx->rsa_blind_signature_camouflage) d0_bignum_free(ctx->rsa_blind_signature_camouflage);
 	if(ctx->r) d0_bignum_free(ctx->r);
-	if(ctx->e) d0_bignum_free(ctx->e);
+	if(ctx->challenge) d0_bignum_free(ctx->challenge);
+	if(ctx->t) d0_bignum_free(ctx->t);
+	if(ctx->g_to_t) d0_bignum_free(ctx->g_to_t);
+	if(ctx->other_g_to_t) d0_bignum_free(ctx->other_g_to_t);
 	memset(ctx, 0, sizeof(*ctx));
 }
 
-void d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t *src)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t *src)
 {
 	d0_blind_id_clear(ctx);
-	if(src->rsa_n) ctx->rsa_n = d0_bignum_mov(NULL, src->rsa_n);
-	if(src->rsa_e) ctx->rsa_e = d0_bignum_mov(NULL, src->rsa_e);
-	if(src->rsa_d) ctx->rsa_d = d0_bignum_mov(NULL, src->rsa_d);
-	if(src->schnorr_G) ctx->schnorr_G = d0_bignum_mov(NULL, src->schnorr_G);
-	if(src->schnorr_s) ctx->schnorr_s = d0_bignum_mov(NULL, src->schnorr_s);
-	if(src->schnorr_4_to_s) ctx->schnorr_4_to_s = d0_bignum_mov(NULL, ctx->schnorr_G);
-	if(src->schnorr_4_to_s_signature) ctx->schnorr_4_to_s_signature = d0_bignum_mov(NULL, src->schnorr_4_to_s_signature);
-	if(src->rn) ctx->rn = d0_bignum_mov(NULL, src->rn);
-	if(src->r) ctx->r = d0_bignum_mov(NULL, src->r);
-	if(src->e) ctx->e = d0_bignum_mov(NULL, src->e);
-	// TODO xnbh, msg, msglen?
+	if(src->rsa_n) CHECK_ASSIGN(ctx->rsa_n, d0_bignum_mov(NULL, src->rsa_n));
+	if(src->rsa_e) CHECK_ASSIGN(ctx->rsa_e, d0_bignum_mov(NULL, src->rsa_e));
+	if(src->rsa_d) CHECK_ASSIGN(ctx->rsa_d, d0_bignum_mov(NULL, src->rsa_d));
+	if(src->schnorr_G) CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_mov(NULL, src->schnorr_G));
+	if(src->schnorr_s) CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_mov(NULL, src->schnorr_s));
+	if(src->schnorr_g_to_s) CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mov(NULL, src->schnorr_g_to_s));
+	if(src->schnorr_H_g_to_s_signature) CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_bignum_mov(NULL, src->schnorr_H_g_to_s_signature));
+	if(src->rsa_blind_signature_camouflage) CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_mov(NULL, src->rsa_blind_signature_camouflage));
+	if(src->r) CHECK_ASSIGN(ctx->r, d0_bignum_mov(NULL, src->r));
+	if(src->challenge) CHECK_ASSIGN(ctx->challenge, d0_bignum_mov(NULL, src->challenge));
+	if(src->t) CHECK_ASSIGN(ctx->t, d0_bignum_mov(NULL, src->t));
+	if(src->g_to_t) CHECK_ASSIGN(ctx->g_to_t, d0_bignum_mov(NULL, src->g_to_t));
+	if(src->other_g_to_t) CHECK_ASSIGN(ctx->other_g_to_t, d0_bignum_mov(NULL, src->other_g_to_t));
+	memcpy(ctx->msg, src->msg, sizeof(ctx->msg));
+	ctx->msglen = src->msglen;
+	memcpy(ctx->msghash, src->msghash, sizeof(ctx->msghash));
+	return 1;
+fail:
+	d0_blind_id_clear(ctx);
+	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key(d0_blind_id_t *ctx, int k)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_key_fastreject(d0_blind_id_t *ctx, int k, d0_fastreject_function reject, void *pass)
 {
-	d0_blind_id_clear(ctx);
+	REPLACING(rsa_e); REPLACING(rsa_d); REPLACING(rsa_n);
+
 	CHECK_ASSIGN(ctx->rsa_e, d0_bignum_int(ctx->rsa_e, 65537));
 	CHECK_ASSIGN(ctx->rsa_d, d0_bignum_zero(ctx->rsa_d));
 	CHECK_ASSIGN(ctx->rsa_n, d0_bignum_zero(ctx->rsa_n));
-	CHECK(d0_rsa_generate_key(k+1, ctx->rsa_e, ctx->rsa_d, ctx->rsa_n)); // must fit G for sure
+	if(reject)
+		CHECK(d0_rsa_generate_key_fastreject(k+1, reject, ctx, pass)); // must fit G for sure
+	else
+		CHECK(d0_rsa_generate_key(k+1, ctx->rsa_e, ctx->rsa_d, ctx->rsa_n)); // must fit G for sure
 	return 1;
 fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_key(d0_blind_id_t *ctx, int k)
+{
+	return d0_blind_id_generate_private_key_fastreject(ctx, k, NULL, NULL);
+}
+
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_private_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
 {
-	d0_iobuf_t *in = d0_iobuf_open_read(inbuf, inbuflen);
+	d0_iobuf_t *in = NULL;
+
+	REPLACING(rsa_n); REPLACING(rsa_e); REPLACING(rsa_d);
+
+	in = d0_iobuf_open_read(inbuf, inbuflen);
+
 	CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
 	CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
 	CHECK_ASSIGN(ctx->rsa_d, d0_iobuf_read_bignum(in, ctx->rsa_d));
@@ -248,9 +396,13 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_public_key(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
 {
-	d0_iobuf_t *in = d0_iobuf_open_read(inbuf, inbuflen);
+	d0_iobuf_t *in = NULL;
+
+	REPLACING(rsa_n); REPLACING(rsa_e);
+
+	in = d0_iobuf_open_read(inbuf, inbuflen);
 	CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, ctx->rsa_n));
 	CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, ctx->rsa_e));
 	return d0_iobuf_close(in, NULL);
@@ -260,12 +412,9 @@ fail:
 	return 0;
 }
 
-#define USING(x) if(!(ctx->x)) return 0
-#define REPLACING(x)
-
-WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_key(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_private_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
 {
-	d0_iobuf_t *out;
+	d0_iobuf_t *out = NULL;
 
 	USING(rsa_n); USING(rsa_e); USING(rsa_d);
 
@@ -280,9 +429,9 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_key(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
 {
-	d0_iobuf_t *out;
+	d0_iobuf_t *out = NULL;
 
 	USING(rsa_n); USING(rsa_e);
 
@@ -297,7 +446,39 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_modulus(d0_blind_id_t *ctx)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_fingerprint64_public_key(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+{
+	d0_iobuf_t *out = NULL;
+	static unsigned char convbuf[2048];
+	d0_iobuf_t *conv = NULL;
+	size_t sz, n;
+
+	USING(rsa_n); USING(rsa_e);
+
+	out = d0_iobuf_open_write(outbuf, *outbuflen);
+	conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
+
+	CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
+	CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
+	CHECK(d0_iobuf_close(conv, &sz));
+	conv = NULL;
+
+	n = (*outbuflen / 4) * 3;
+	if(n > SHA_DIGESTSIZE)
+		n = SHA_DIGESTSIZE;
+	CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
+	CHECK(d0_iobuf_conv_base64_out(out));
+
+	return d0_iobuf_close(out, outbuflen);
+
+fail:
+	if(conv)
+		d0_iobuf_close(conv, &sz);
+	d0_iobuf_close(out, outbuflen);
+	return 0;
+}
+
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_id_modulus(d0_blind_id_t *ctx)
 {
 	USING(rsa_n);
 	REPLACING(schnorr_G);
@@ -309,9 +490,13 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id_modulus(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_private_id_modulus(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
 {
-	d0_iobuf_t *in = d0_iobuf_open_read(inbuf, inbuflen);
+	d0_iobuf_t *in = NULL;
+
+	REPLACING(schnorr_G);
+
+	in = d0_iobuf_open_read(inbuf, inbuflen);
 	CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, ctx->schnorr_G));
 	return d0_iobuf_close(in, NULL);
 
@@ -320,9 +505,9 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_modulus(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_private_id_modulus(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
 {
-	d0_iobuf_t *out;
+	d0_iobuf_t *out = NULL;
 
 	USING(schnorr_G);
 
@@ -335,35 +520,47 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_start(d0_blind_id_t *ctx)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_generate_private_id_start(d0_blind_id_t *ctx)
 {
-	// temps: temp0 order
+	// temps: temp0 = order
 	USING(schnorr_G);
-	REPLACING(schnorr_s); REPLACING(schnorr_4_to_s);
+	REPLACING(schnorr_s); REPLACING(schnorr_g_to_s);
 
 	CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
 	CHECK_ASSIGN(ctx->schnorr_s, d0_bignum_rand_range(ctx->schnorr_s, zero, temp0));
-	CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_bignum_mod_pow(ctx->schnorr_4_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
-	CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_bignum_zero(ctx->schnorr_4_to_s_signature));
+	CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_bignum_mod_pow(ctx->schnorr_g_to_s, four, ctx->schnorr_s, ctx->schnorr_G));
+	CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
 	return 1;
 
 fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+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;
+	d0_iobuf_t *out = NULL;
+	static unsigned char convbuf[2048], shabuf[2048];
+	size_t sz;
 
-	// temps: temp0 temp1
-	USING(rsa_n); USING(rsa_e); USING(schnorr_4_to_s);
-	REPLACING(rn);
+	// temps: temp0 rsa_blind_signature_camouflage^challenge, temp1 (4^s)*rsa_blind_signature_camouflage^challenge
+	USING(rsa_n); USING(rsa_e); USING(schnorr_g_to_s);
+	REPLACING(rsa_blind_signature_camouflage);
 
 	out = d0_iobuf_open_write(outbuf, *outbuflen);
 
-	CHECK_ASSIGN(ctx->rn, d0_bignum_rand_bit_atmost(ctx->rn, d0_bignum_size(ctx->rsa_n)));
-	CHECK(d0_bignum_mod_pow(temp0, ctx->rn, ctx->rsa_e, ctx->rsa_n));
-	CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_4_to_s, temp0, ctx->rsa_n));
+	CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_bignum_rand_bit_atmost(ctx->rsa_blind_signature_camouflage, d0_bignum_size(ctx->rsa_n)));
+	CHECK(d0_bignum_mod_pow(temp0, ctx->rsa_blind_signature_camouflage, ctx->rsa_e, ctx->rsa_n));
+
+	// we will actually sign HA(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));
+
+	// hash complete
+	CHECK(d0_bignum_mod_mul(temp1, temp2, temp0, ctx->rsa_n));
 	CHECK(d0_iobuf_write_bignum(out, temp1));
 	return d0_iobuf_close(out, outbuflen);
 
@@ -372,12 +569,12 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_answer_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen, char *outbuf, size_t *outbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_answer_private_id_request(const d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen, char *outbuf, size_t *outbuflen)
 {
-	d0_iobuf_t *in;
-	d0_iobuf_t *out;
+	d0_iobuf_t *in = NULL;
+	d0_iobuf_t *out = NULL;
 
-	// temps: temp0 temp1
+	// temps: temp0 input, temp1 temp0^d
 	USING(rsa_d); USING(rsa_n);
 
 	in = d0_iobuf_open_read(inbuf, inbuflen);
@@ -396,19 +593,19 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
 {
-	d0_iobuf_t *in;
+	d0_iobuf_t *in = NULL;
 
-	// temps: temp0 temp1
-	USING(rn); USING(rsa_n);
-	REPLACING(schnorr_4_to_s_signature);
+	// temps: temp0 input, temp1 rsa_blind_signature_camouflage^-1
+	USING(rsa_blind_signature_camouflage); USING(rsa_n);
+	REPLACING(schnorr_H_g_to_s_signature);
 
 	in = d0_iobuf_open_read(inbuf, inbuflen);
 
 	CHECK(d0_iobuf_read_bignum(in, temp0));
-	CHECK(d0_bignum_mod_inv(temp1, ctx->rn, ctx->rsa_n));
-	CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_bignum_mod_mul(ctx->schnorr_4_to_s_signature, temp0, temp1, ctx->rsa_n));
+	CHECK(d0_bignum_mod_inv(temp1, ctx->rsa_blind_signature_camouflage, ctx->rsa_n));
+	CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_bignum_mod_mul(ctx->schnorr_H_g_to_s_signature, temp0, temp1, ctx->rsa_n));
 
 	return d0_iobuf_close(in, NULL);
 
@@ -417,17 +614,51 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_private_id_request_camouflage(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
 {
-	d0_iobuf_t *in;
+	d0_iobuf_t *in = NULL;
 
-	REPLACING(schnorr_s); REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
+	REPLACING(rsa_blind_signature_camouflage);
+
+	in = d0_iobuf_open_read(inbuf, inbuflen);
+
+	CHECK_ASSIGN(ctx->rsa_blind_signature_camouflage, d0_iobuf_read_bignum(in, ctx->rsa_blind_signature_camouflage));
+
+	return d0_iobuf_close(in, NULL);
+
+fail:
+	d0_iobuf_close(in, NULL);
+	return 0;
+}
+
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_private_id_request_camouflage(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+{
+	d0_iobuf_t *out = NULL;
+
+	USING(rsa_blind_signature_camouflage);
+
+	out = d0_iobuf_open_write(outbuf, *outbuflen);
+
+	CHECK(d0_iobuf_write_bignum(out, ctx->rsa_blind_signature_camouflage));
+
+	return d0_iobuf_close(out, outbuflen);
+
+fail:
+	d0_iobuf_close(out, outbuflen);
+	return 0;
+}
+
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_private_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
+{
+	d0_iobuf_t *in = NULL;
+
+	REPLACING(schnorr_s); REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
 
 	in = d0_iobuf_open_read(inbuf, inbuflen);
 
 	CHECK_ASSIGN(ctx->schnorr_s, d0_iobuf_read_bignum(in, ctx->schnorr_s));
-	CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
-	CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
+	CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
+	CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
 
 	return d0_iobuf_close(in, NULL);
 
@@ -436,16 +667,16 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
 {
-	d0_iobuf_t *in;
+	d0_iobuf_t *in = NULL;
 
-	REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
+	REPLACING(schnorr_g_to_s); REPLACING(schnorr_H_g_to_s_signature);
 
 	in = d0_iobuf_open_read(inbuf, inbuflen);
 
-	CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
-	CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
+	CHECK_ASSIGN(ctx->schnorr_g_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_g_to_s));
+	CHECK_ASSIGN(ctx->schnorr_H_g_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_H_g_to_s_signature));
 
 	return d0_iobuf_close(in, NULL);
 
@@ -454,17 +685,17 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_private_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
 {
-	d0_iobuf_t *out;
+	d0_iobuf_t *out = NULL;
 
-	USING(schnorr_s); USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
+	USING(schnorr_s); USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
 
 	out = d0_iobuf_open_write(outbuf, *outbuflen);
 
 	CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_s));
-	CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
-	CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
+	CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
+	CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
 
 	return d0_iobuf_close(out, outbuflen);
 
@@ -473,16 +704,16 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_write_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
 {
-	d0_iobuf_t *out;
+	d0_iobuf_t *out = NULL;
 
-	USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
+	USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
 
 	out = d0_iobuf_open_write(outbuf, *outbuflen);
 
-	CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
-	CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
+	CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_g_to_s));
+	CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_H_g_to_s_signature));
 
 	return d0_iobuf_close(out, outbuflen);
 
@@ -491,22 +722,24 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_start(d0_blind_id_t *ctx, BOOL is_first, 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, 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)
 {
-	d0_iobuf_t *out;
-	unsigned char convbuf[1024];
-	d0_iobuf_t *conv;
-	size_t sz;
+	d0_iobuf_t *out = NULL;
+	static unsigned char convbuf[1024];
+	d0_iobuf_t *conv = NULL;
+	size_t sz = 0;
+	D0_BOOL failed = 0;
 
+	// temps: temp0 order, temp0 4^r
 	if(is_first)
 	{
-		USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
+		USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
 	}
 	USING(schnorr_G);
-	REPLACING(r);
+	REPLACING(r); REPLACING(t); REPLACING(g_to_t);
 
 	out = d0_iobuf_open_write(outbuf, *outbuflen);
 
@@ -515,21 +748,32 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_start(d0_blind_
 		// send ID
 		if(send_modulus)
 			CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
-		CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s));
-		CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
+		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 ID scheme
 	// generate random number r; x = g^r; send hash of x, 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(temp0, four, ctx->r, ctx->schnorr_G));
+	//CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
+
+	// initialize Signed Diffie Hellmann
+	// we already have the group order in temp1
+	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(!failed);
 
 	// hash it, hash it, everybody hash it
 	conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
 	CHECK(d0_iobuf_write_bignum(conv, temp0));
+	CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
 	CHECK(d0_iobuf_write_packet(conv, msg, msglen));
 	CHECK(d0_iobuf_write_bignum(conv, temp0));
+	CHECK(d0_iobuf_write_bignum(conv, ctx->g_to_t));
 	d0_iobuf_close(conv, &sz);
 	conv = NULL;
 	CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), SCHNORR_HASHSIZE) == SCHNORR_HASHSIZE);
@@ -542,29 +786,33 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_challenge(d0_blind_id_t *ctx, BOOL is_first, BOOL recv_modulus, const char *inbuf, size_t inbuflen, char *outbuf, size_t *outbuflen, BOOL *status)
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_authenticate_with_private_id_challenge(d0_blind_id_t *ctx, D0_BOOL is_first, D0_BOOL recv_modulus, const char *inbuf, size_t inbuflen, char *outbuf, size_t *outbuflen, D0_BOOL *status)
 //   first run: get 4^s, 4^s signature
 //   1. check sig
 //   2. save HASH(4^r)
-//   3. send challenge e of SCHNORR_BITS
+//   3. send challenge challenge of SCHNORR_BITS
 {
-	d0_iobuf_t *in;
-	d0_iobuf_t *out;
+	d0_iobuf_t *in = NULL;
+	d0_iobuf_t *out = NULL;
+	static unsigned char shabuf[2048];
+	size_t sz;
 
+	// temps: temp0 order, temp0 signature check
 	if(is_first)
 	{
-		REPLACING(schnorr_4_to_s); REPLACING(k); REPLACING(schnorr_4_to_s_signature);
-		USING(rsa_n);
-		if(!recv_modulus)
+		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_4_to_s_signature); USING(schnorr_4_to_s);
+		USING(schnorr_g_to_s); USING(schnorr_H_g_to_s_signature);
 		USING(schnorr_G);
 	}
 	USING(rsa_e); USING(rsa_n);
-	REPLACING(e); REPLACING(msg); REPLACING(msglen);
+	REPLACING(challenge); REPLACING(msg); REPLACING(msglen); REPLACING(msghash); REPLACING(r); REPLACING(t);
 
 	in = d0_iobuf_open_read(inbuf, inbuflen);
 	out = d0_iobuf_open_write(outbuf, *outbuflen);
@@ -577,33 +825,51 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_challenge(d0_bl
 			CHECK(d0_bignum_cmp(ctx->schnorr_G, zero) > 0);
 			CHECK(d0_bignum_cmp(ctx->schnorr_G, ctx->rsa_n) < 0);
 		}
-		CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s));
-		CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, zero) > 0);
-		CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, ctx->schnorr_G) < 0);
-		CHECK_ASSIGN(ctx->schnorr_4_to_s_signature, d0_iobuf_read_bignum(in, ctx->schnorr_4_to_s_signature));
-		CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero) >= 0);
-		CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s_signature, ctx->rsa_n) < 0);
-
-		// check signature of key (t = k^d, so, t^e = k)
-		CHECK(d0_bignum_mod_pow(temp0, ctx->schnorr_4_to_s_signature, ctx->rsa_e, ctx->rsa_n));
-		if(d0_bignum_cmp(temp0, ctx->schnorr_4_to_s))
+		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_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));
+
+		// 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_4_to_s_signature));
+			CHECK(d0_bignum_zero(ctx->schnorr_H_g_to_s_signature));
 		}
 	}
 
-	CHECK(d0_iobuf_read_raw(in, ctx->xnbh, SCHNORR_HASHSIZE));
+	CHECK(d0_iobuf_read_raw(in, ctx->msghash, SCHNORR_HASHSIZE));
 	ctx->msglen = MSGSIZE;
 	CHECK(d0_iobuf_read_packet(in, ctx->msg, &ctx->msglen));
 
 	// send challenge
-	CHECK_ASSIGN(ctx->e, d0_bignum_rand_bit_atmost(ctx->e, SCHNORR_BITS));
+	CHECK_ASSIGN(ctx->challenge, d0_bignum_rand_bit_atmost(ctx->challenge, SCHNORR_BITS));
+	CHECK(d0_iobuf_write_bignum(out, ctx->challenge));
 
-	CHECK(d0_iobuf_write_bignum(out, ctx->e));
+	// Diffie Hellmann send
+	CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
+	CHECK_ASSIGN(ctx->t, d0_bignum_rand_range(ctx->t, zero, temp0));
+	CHECK(d0_bignum_mod_pow(temp0, four, ctx->t, ctx->schnorr_G));
+	CHECK(d0_iobuf_write_bignum(out, temp0));
 
 	if(status)
-		*status = !!d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero);
+		*status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
 
 	d0_iobuf_close(in, NULL);
 	return d0_iobuf_close(out, outbuflen);
@@ -614,31 +880,38 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_response(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen, char *outbuf, size_t *outbuflen)
-//   1. read challenge e of SCHNORR_BITS
-//   2. reply with r + s * e mod order
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_authenticate_with_private_id_response(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen, char *outbuf, size_t *outbuflen)
+//   1. read challenge challenge of SCHNORR_BITS
+//   2. reply with r + s * challenge mod order
 {
-	d0_iobuf_t *in;
-	d0_iobuf_t *out;
+	d0_iobuf_t *in = NULL;
+	d0_iobuf_t *out = NULL;
 
-	// temps: 0 order, 1 prod, 2 y, 3 e
-	USING(schnorr_G); USING(schnorr_s); USING(r);
+	// temps: 0 order, 1 prod, 2 y, 3 challenge
+	REPLACING(other_g_to_t); REPLACING(t);
+	USING(schnorr_G); USING(schnorr_s); USING(r); USING(g_to_t);
 
 	in = d0_iobuf_open_read(inbuf, inbuflen);
 	out = d0_iobuf_open_write(outbuf, *outbuflen);
 
 	CHECK(d0_iobuf_read_bignum(in, temp3));
-	// TODO check if >= 2^SCHNORR_BITS or < 0, if yes, then fail (needed for zero knowledge)
 	CHECK(d0_bignum_cmp(temp3, zero) >= 0);
 	CHECK(d0_bignum_size(temp3) <= SCHNORR_BITS);
 
 	// send response for schnorr ID scheme
-	// i.e. r + ctx->schnorr_s * temp3
+	// i.challenge. r + ctx->schnorr_s * temp3
 	CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
 	CHECK(d0_bignum_mod_mul(temp1, ctx->schnorr_s, temp3, temp0));
 	CHECK(d0_bignum_mod_add(temp2, temp1, ctx->r, temp0));
 	CHECK(d0_iobuf_write_bignum(out, temp2));
 
+	// Diffie Hellmann recv
+	CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
+	CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
+	CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
+	// Diffie Hellmann send
+	CHECK(d0_iobuf_write_bignum(out, ctx->g_to_t));
+
 	d0_iobuf_close(in, NULL);
 	return d0_iobuf_close(out, outbuflen);
 
@@ -648,52 +921,58 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_verify(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen, char *msg, ssize_t *msglen, BOOL *status)
-//   1. read y = r + s * e mod order
-//   2. verify: g^y (g^s)^-e = g^(r+s*e-s*e) = g^r
+D0_WARN_UNUSED_RESULT D0_BOOL d0_blind_id_authenticate_with_private_id_verify(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen, char *msg, size_t *msglen, D0_BOOL *status)
+//   1. read y = r + s * challenge mod order
+//   2. verify: g^y (g^s)^-challenge = g^(r+s*challenge-s*challenge) = g^r
 //      (check using H(g^r) which we know)
 {
-	d0_iobuf_t *in;
-	unsigned char convbuf[1024];
-	d0_iobuf_t *conv;
+	d0_iobuf_t *in = NULL;
+	static unsigned char convbuf[1024];
+	d0_iobuf_t *conv = NULL;
 	size_t sz;
 
 	// temps: 0 y 1 order
-	USING(e); USING(schnorr_G);
+	USING(challenge); USING(schnorr_G);
+	REPLACING(other_g_to_t);
 
 	in = d0_iobuf_open_read(inbuf, inbuflen);
 
-	*msglen = -1;
 	CHECK(d0_dl_get_order(temp1, ctx->schnorr_G));
 	CHECK(d0_iobuf_read_bignum(in, temp0));
 	CHECK(d0_bignum_cmp(temp0, zero) >= 0);
 	CHECK(d0_bignum_cmp(temp0, temp1) < 0);
 
 	// verify schnorr ID scheme
-	// we need 4^temp0 (g^s)^-e
-	CHECK(d0_bignum_neg(temp1, ctx->e));
-	CHECK(d0_bignum_mod_pow(temp2, ctx->schnorr_4_to_s, temp1, ctx->schnorr_G));
+	// we need 4^r = 4^temp0 (g^s)^-challenge
+	CHECK(d0_bignum_mod_inv(temp1, ctx->schnorr_g_to_s, ctx->schnorr_G));
+	CHECK(d0_bignum_mod_pow(temp2, temp1, ctx->challenge, ctx->schnorr_G));
 	CHECK(d0_bignum_mod_pow(temp1, four, temp0, ctx->schnorr_G));
-	CHECK(d0_bignum_mod_mul(temp3, temp1, temp2, ctx->schnorr_G));
-	// hash must be equal to xnbh
+	CHECK_ASSIGN(temp3, d0_bignum_mod_mul(temp3, temp1, temp2, ctx->schnorr_G));
+
+	// Diffie Hellmann recv
+	CHECK_ASSIGN(ctx->other_g_to_t, d0_iobuf_read_bignum(in, ctx->other_g_to_t));
+	CHECK(d0_bignum_cmp(ctx->other_g_to_t, zero) > 0);
+	CHECK(d0_bignum_cmp(ctx->other_g_to_t, ctx->schnorr_G) < 0);
 
 	// hash it, hash it, everybody hash it
 	conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
 	CHECK(d0_iobuf_write_bignum(conv, temp3));
+	CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
 	CHECK(d0_iobuf_write_packet(conv, ctx->msg, ctx->msglen));
 	CHECK(d0_iobuf_write_bignum(conv, temp3));
+	CHECK(d0_iobuf_write_bignum(conv, ctx->other_g_to_t));
 	d0_iobuf_close(conv, &sz);
 	conv = NULL;
-	if(memcmp(sha(convbuf, sz), ctx->xnbh, SCHNORR_HASHSIZE))
+	if(memcmp(sha(convbuf, sz), ctx->msghash, SCHNORR_HASHSIZE))
 	{
 		// FAIL (not owned by player)
 		goto fail;
 	}
 
 	if(status)
-		*status = !!d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero);
+		*status = !!d0_bignum_cmp(ctx->schnorr_H_g_to_s_signature, zero);
 
-	if(ctx->msglen <= (size_t) *msglen)
+	if(ctx->msglen <= *msglen)
 		memcpy(msg, ctx->msg, ctx->msglen);
 	else
 		memcpy(msg, ctx->msg, *msglen);
@@ -707,37 +986,75 @@ fail:
 	return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+D0_WARN_UNUSED_RESULT D0_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;
+}
+
+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;
-	d0_iobuf_t *conv;
+	d0_iobuf_t *out = NULL;
 	static unsigned char convbuf[1024];
+	d0_iobuf_t *conv = NULL;
 	size_t sz, n;
 
-	USING(schnorr_4_to_s);
+	USING(rsa_n);
+	USING(rsa_e);
+	USING(schnorr_g_to_s);
 
 	out = d0_iobuf_open_write(outbuf, *outbuflen);
 	conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
 
-	CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_4_to_s));
+	CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_n));
+	CHECK(d0_iobuf_write_bignum(conv, ctx->rsa_e));
+	CHECK(d0_iobuf_write_bignum(conv, ctx->schnorr_g_to_s));
 	CHECK(d0_iobuf_close(conv, &sz));
 	conv = NULL;
 
 	n = (*outbuflen / 4) * 3;
 	if(n > SHA_DIGESTSIZE)
 		n = SHA_DIGESTSIZE;
-	if(d0_iobuf_write_raw(out, sha(convbuf, sz), n) != n)
-		goto fail;
-	if(!d0_iobuf_conv_base64_out(out))
-		goto fail;
+	CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
+	CHECK(d0_iobuf_conv_base64_out(out));
 
 	return d0_iobuf_close(out, outbuflen);
 
 fail:
 	if(conv)
-		if(!d0_iobuf_close(conv, &sz)) { }
-	if(!d0_iobuf_close(out, outbuflen))
-		return 0;
+		d0_iobuf_close(conv, &sz);
+	d0_iobuf_close(out, outbuflen);
+	return 0;
+}
+
+D0_BOOL d0_blind_id_sessionkey_public_id(const d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+{
+	USING(t); USING(other_g_to_t); USING(schnorr_G);
+
+	// 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);
+
+fail:
 	return 0;
 }
 
@@ -753,3 +1070,11 @@ void d0_blind_id_free(d0_blind_id_t *a)
 	d0_blind_id_clear(a);
 	d0_free(a);
 }
+
+void d0_blind_id_util_sha256(char *out, const char *in, size_t n)
+{
+	SHA256_CTX context;
+	SHA256_Init(&context);
+	SHA256_Update(&context, (const unsigned char *) in, n);
+	return SHA256_Final((unsigned char *) out, &context);
+}