]> de.git.xonotic.org Git - xonotic/d0_blind_id.git/blobdiff - d0_blind_id.c
use /dev/urandom
[xonotic/d0_blind_id.git] / d0_blind_id.c
index 617b473f4d4fb6edd5c3368fa5039569dc98ed18..bdf8023a7df946c224cfdc3a5d7eccd03e75fec8 100644 (file)
@@ -51,7 +51,7 @@ struct d0_blind_id_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;
+       d0_bignum_t *schnorr_4_to_s_signature; // 0 when signature is invalid
 
        // temp data
        d0_bignum_t *rn; // random number blind signature
@@ -60,14 +60,18 @@ struct d0_blind_id_s
        d0_bignum_t *e; // challenge
        char msg[MSGSIZE]; // message
        size_t msglen; // message length
+       d0_bignum_t *other_4_to_r; // for DH key exchange
 };
 
 #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 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_blind_id_INITIALIZE(void)
 {
        d0_bignum_INITIALIZE();
        CHECK_ASSIGN(zero, d0_bignum_int(zero, 0));
@@ -82,7 +86,7 @@ fail:
        ;
 }
 
-void d0_blind_id_SHUTDOWN()
+void d0_blind_id_SHUTDOWN(void)
 {
        d0_bignum_free(zero);
        d0_bignum_free(one);
@@ -141,10 +145,12 @@ BOOL d0_rsa_generate_key(size_t size, const d0_bignum_t *e, d0_bignum_t *d, d0_b
        // uses temp0 to temp4
        int fail = 0;
        int gcdfail = 0;
-       if(size < 16)
-               size = 16;
        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));
@@ -202,6 +208,7 @@ void d0_blind_id_clear(d0_blind_id_t *ctx)
        if(ctx->rn) d0_bignum_free(ctx->rn);
        if(ctx->r) d0_bignum_free(ctx->r);
        if(ctx->e) d0_bignum_free(ctx->e);
+       if(ctx->other_4_to_r) d0_bignum_free(ctx->other_4_to_r);
        memset(ctx, 0, sizeof(*ctx));
 }
 
@@ -218,31 +225,36 @@ void d0_blind_id_copy(d0_blind_id_t *ctx, const d0_blind_id_t *src)
        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->other_4_to_r) ctx->other_4_to_r = d0_bignum_mov(NULL, src->other_4_to_r);
+       memcpy(ctx->msg, src->msg, sizeof(ctx->msg));
+       ctx->msglen = src->msglen;
+       memcpy(ctx->xnbh, src->xnbh, sizeof(ctx->xnbh));
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_keys(d0_blind_id_t *ctx, int k)
+WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_key(d0_blind_id_t *ctx, int k)
 {
-       d0_blind_id_clear(ctx);
-       CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_new());
-       CHECK(d0_dl_generate_key(k, ctx->schnorr_G));
-       CHECK_ASSIGN(ctx->rsa_e, d0_bignum_int(NULL, 65537));
-       CHECK_ASSIGN(ctx->rsa_d, d0_bignum_new());
-       CHECK_ASSIGN(ctx->rsa_n, d0_bignum_new());
+       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
        return 1;
 fail:
        return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_read_private_keys(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
+WARN_UNUSED_RESULT 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_blind_id_clear(ctx);
-       CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, NULL));
-       CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, NULL));
-       CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, NULL));
-       CHECK_ASSIGN(ctx->rsa_d, d0_iobuf_read_bignum(in, NULL));
+       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));
        return d0_iobuf_close(in, NULL);
 
 fail:
@@ -250,13 +262,15 @@ fail:
        return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_keys(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
+WARN_UNUSED_RESULT 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_blind_id_clear(ctx);
-       CHECK_ASSIGN(ctx->schnorr_G, d0_iobuf_read_bignum(in, NULL));
-       CHECK_ASSIGN(ctx->rsa_n, d0_iobuf_read_bignum(in, NULL));
-       CHECK_ASSIGN(ctx->rsa_e, d0_iobuf_read_bignum(in, NULL));
+       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);
 
 fail:
@@ -264,16 +278,13 @@ fail:
        return 0;
 }
 
-#define USING(x) if(!(ctx->x)) return 0
-#define WRITING(x,f) if(ctx->x) { f(ctx->x); ctx->x = NULL; }
-#define REPLACING(x)
-
-WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_keys(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_key(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
 {
+       d0_iobuf_t *out = NULL;
+
        USING(rsa_n); USING(rsa_e); USING(rsa_d);
 
-       d0_iobuf_t *out = d0_iobuf_open_write(outbuf, *outbuflen);
-       CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
+       out = d0_iobuf_open_write(outbuf, *outbuflen);
        CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
        CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
        CHECK(d0_iobuf_write_bignum(out, ctx->rsa_d));
@@ -284,12 +295,13 @@ fail:
        return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_keys(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_key(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
 {
-       USING(rsa_n); USING(rsa_e); USING(rsa_d);
+       d0_iobuf_t *out = NULL;
 
-       d0_iobuf_t *out = d0_iobuf_open_write(outbuf, *outbuflen);
-       CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
+       USING(rsa_n); USING(rsa_e);
+
+       out = d0_iobuf_open_write(outbuf, *outbuflen);
        CHECK(d0_iobuf_write_bignum(out, ctx->rsa_n));
        CHECK(d0_iobuf_write_bignum(out, ctx->rsa_e));
        return d0_iobuf_close(out, outbuflen);
@@ -300,15 +312,58 @@ fail:
        return 0;
 }
 
+WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_modulus(d0_blind_id_t *ctx)
+{
+       USING(rsa_n);
+       REPLACING(schnorr_G);
+
+       CHECK_ASSIGN(ctx->schnorr_G, d0_bignum_zero(ctx->schnorr_G));
+       CHECK(d0_dl_generate_key(d0_bignum_size(ctx->rsa_n)-1, ctx->schnorr_G));
+       return 1;
+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_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);
+
+fail:
+       d0_iobuf_close(in, NULL);
+       return 0;
+}
+
+WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id_modulus(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+{
+       d0_iobuf_t *out = NULL;
+
+       USING(schnorr_G);
+
+       out = d0_iobuf_open_write(outbuf, *outbuflen);
+       CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_G));
+       return d0_iobuf_close(out, outbuflen);
+
+fail:
+       d0_iobuf_close(out, outbuflen);
+       return 0;
+}
+
 WARN_UNUSED_RESULT 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);
 
        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));
        return 1;
 
 fail:
@@ -317,11 +372,13 @@ fail:
 
 WARN_UNUSED_RESULT BOOL d0_blind_id_generate_private_id_request(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
 {
-       // temps: temp0 temp1
+       d0_iobuf_t *out = NULL;
+
+       // temps: temp0 rn^e, temp1 (4^s)*rn^e
        USING(rsa_n); USING(rsa_e); USING(schnorr_4_to_s);
        REPLACING(rn);
 
-       d0_iobuf_t *out = d0_iobuf_open_write(outbuf, *outbuflen);
+       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));
@@ -336,11 +393,14 @@ fail:
 
 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)
 {
-       // temps: temp0 temp1
+       d0_iobuf_t *in = NULL;
+       d0_iobuf_t *out = NULL;
+
+       // temps: temp0 input, temp1 temp0^d
        USING(rsa_d); USING(rsa_n);
 
-       d0_iobuf_t *in = d0_iobuf_open_read(inbuf, inbuflen);
-       d0_iobuf_t *out = d0_iobuf_open_write(outbuf, *outbuflen);
+       in = d0_iobuf_open_read(inbuf, inbuflen);
+       out = d0_iobuf_open_write(outbuf, *outbuflen);
 
        CHECK(d0_iobuf_read_bignum(in, temp0));
        CHECK(d0_bignum_mod_pow(temp1, temp0, ctx->rsa_d, ctx->rsa_n));
@@ -357,11 +417,13 @@ fail:
 
 WARN_UNUSED_RESULT BOOL d0_blind_id_finish_private_id_request(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
 {
-       // temps: temp0 temp1
+       d0_iobuf_t *in = NULL;
+
+       // temps: temp0 input, temp1 rn^-1
        USING(rn); USING(rsa_n);
        REPLACING(schnorr_4_to_s_signature);
 
-       d0_iobuf_t *in = d0_iobuf_open_read(inbuf, inbuflen);
+       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));
@@ -376,9 +438,11 @@ fail:
 
 WARN_UNUSED_RESULT 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_4_to_s); REPLACING(schnorr_4_to_s_signature);
 
-       d0_iobuf_t *in = d0_iobuf_open_read(inbuf, inbuflen);
+       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));
@@ -393,9 +457,11 @@ fail:
 
 WARN_UNUSED_RESULT BOOL d0_blind_id_read_public_id(d0_blind_id_t *ctx, const char *inbuf, size_t inbuflen)
 {
+       d0_iobuf_t *in = NULL;
+
        REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_to_s_signature);
 
-       d0_iobuf_t *in = d0_iobuf_open_read(inbuf, inbuflen);
+       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));
@@ -409,9 +475,11 @@ fail:
 
 WARN_UNUSED_RESULT BOOL d0_blind_id_write_private_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
 {
+       d0_iobuf_t *out = NULL;
+
        USING(schnorr_s); USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
 
-       d0_iobuf_t *out = d0_iobuf_open_write(outbuf, *outbuflen);
+       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));
@@ -426,9 +494,11 @@ fail:
 
 WARN_UNUSED_RESULT BOOL d0_blind_id_write_public_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
 {
+       d0_iobuf_t *out = NULL;
+
        USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
 
-       d0_iobuf_t *out = d0_iobuf_open_write(outbuf, *outbuflen);
+       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));
@@ -440,11 +510,17 @@ fail:
        return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_start(d0_blind_id_t *ctx, int is_first, char *msg, size_t msglen, char *outbuf, size_t *outbuflen)
+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)
 // start =
 //   first run: send 4^s, 4^s signature
 //   1. get random r, send HASH(4^r)
 {
+       d0_iobuf_t *out = NULL;
+       static unsigned char convbuf[1024];
+       d0_iobuf_t *conv = NULL;
+       size_t sz = 0;
+
+       // temps: temp0 order, temp0 4^r
        if(is_first)
        {
                USING(schnorr_4_to_s); USING(schnorr_4_to_s_signature);
@@ -452,11 +528,13 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_start(d0_blind_
        USING(schnorr_G);
        REPLACING(r);
 
-       d0_iobuf_t *out = d0_iobuf_open_write(outbuf, *outbuflen);
+       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_4_to_s));
                CHECK(d0_iobuf_write_bignum(out, ctx->schnorr_4_to_s_signature));
        }
@@ -468,9 +546,7 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_start(d0_blind_
        CHECK(d0_bignum_mod_pow(temp0, four, ctx->r, ctx->schnorr_G));
 
        // hash it, hash it, everybody hash it
-       unsigned char convbuf[1024];
-       d0_iobuf_t *conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
-       size_t sz;
+       conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
        CHECK(d0_iobuf_write_bignum(conv, temp0));
        CHECK(d0_iobuf_write_packet(conv, msg, msglen));
        CHECK(d0_iobuf_write_bignum(conv, temp0));
@@ -486,44 +562,57 @@ fail:
        return 0;
 }
 
-WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_challenge(d0_blind_id_t *ctx, int is_first, const char *inbuf, size_t inbuflen, char *outbuf, size_t *outbuflen)
+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)
 //   first run: get 4^s, 4^s signature
 //   1. check sig
 //   2. save HASH(4^r)
 //   3. send challenge e of SCHNORR_BITS
 {
+       d0_iobuf_t *in = NULL;
+       d0_iobuf_t *out = NULL;
+
+       // temps: temp0 order, temp0 signature check
        if(is_first)
        {
-               REPLACING(schnorr_4_to_s); REPLACING(k); REPLACING(schnorr_4_to_s_signature);
-               USING(schnorr_G); USING(rsa_n);
+               REPLACING(schnorr_4_to_s); REPLACING(schnorr_4_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_4_to_s); USING(schnorr_4_to_s_signature);
+               USING(schnorr_G);
        }
        USING(rsa_e); USING(rsa_n);
-       REPLACING(e); REPLACING(msg); REPLACING(msglen);
+       REPLACING(e); REPLACING(msg); REPLACING(msglen); REPLACING(xnbh); REPLACING(r);
 
-       d0_iobuf_t *in = d0_iobuf_open_read(inbuf, inbuflen);
-       d0_iobuf_t *out = d0_iobuf_open_write(outbuf, *outbuflen);
+       in = d0_iobuf_open_read(inbuf, inbuflen);
+       out = d0_iobuf_open_write(outbuf, *outbuflen);
 
        if(is_first)
        {
-               CHECK_ASSIGN(ctx->schnorr_4_to_s, d0_iobuf_read_bignum(in, NULL));
-               CHECK(d0_bignum_cmp(ctx->schnorr_4_to_s, zero) >= 0);
+               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_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))
-       {
-               // FAIL (not signed by Xonotic)
-               goto fail;
-               // TODO: accept the key anyway, but mark as failed signature!
+               // 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))
+               {
+                       // 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_iobuf_read_raw(in, ctx->xnbh, SCHNORR_HASHSIZE));
@@ -535,6 +624,15 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_challenge(d0_bl
 
        CHECK(d0_iobuf_write_bignum(out, ctx->e));
 
+       // Diffie Hellmann
+       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_iobuf_write_bignum(out, temp0));
+
+       if(status)
+               *status = !!d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero);
+
        d0_iobuf_close(in, NULL);
        return d0_iobuf_close(out, outbuflen);
 
@@ -548,17 +646,25 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_response(d0_bli
 //   1. read challenge e of SCHNORR_BITS
 //   2. reply with r + s * e mod order
 {
+       d0_iobuf_t *in = NULL;
+       d0_iobuf_t *out = NULL;
+
        // temps: 0 order, 1 prod, 2 y, 3 e
+       REPLACING(other_4_to_r);
        USING(schnorr_G); USING(schnorr_s); USING(r);
 
-       d0_iobuf_t *in = d0_iobuf_open_read(inbuf, inbuflen);
-       d0_iobuf_t *out = d0_iobuf_open_write(outbuf, *outbuflen);
+       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);
 
+       // Diffie Hellmann
+       CHECK_ASSIGN(ctx->other_4_to_r, d0_iobuf_read_bignum(in, ctx->other_4_to_r));
+       CHECK(d0_bignum_cmp(ctx->other_4_to_r, zero) > 0);
+       CHECK(d0_bignum_cmp(ctx->other_4_to_r, ctx->schnorr_G) < 0);
+
        // send response for schnorr ID scheme
        // i.e. r + ctx->schnorr_s * temp3
        CHECK(d0_dl_get_order(temp0, ctx->schnorr_G));
@@ -575,17 +681,22 @@ 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)
+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, size_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
 //      (check using H(g^r) which we know)
 {
+       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);
+       REPLACING(other_4_to_r);
 
-       d0_iobuf_t *in = d0_iobuf_open_read(inbuf, inbuflen);
+       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);
@@ -596,16 +707,14 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_verify(d0_blind
        CHECK(d0_bignum_neg(temp1, ctx->e));
        CHECK(d0_bignum_mod_pow(temp2, ctx->schnorr_4_to_s, temp1, 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));
+       CHECK_ASSIGN(ctx->other_4_to_r, d0_bignum_mod_mul(ctx->other_4_to_r, temp1, temp2, ctx->schnorr_G));
        // hash must be equal to xnbh
 
        // hash it, hash it, everybody hash it
-       unsigned char convbuf[1024];
-       d0_iobuf_t *conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
-       size_t sz;
-       CHECK(d0_iobuf_write_bignum(conv, temp3));
+       conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
+       CHECK(d0_iobuf_write_bignum(conv, ctx->other_4_to_r));
        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_4_to_r));
        d0_iobuf_close(conv, &sz);
        conv = NULL;
        if(memcmp(sha(convbuf, sz), ctx->xnbh, SCHNORR_HASHSIZE))
@@ -614,7 +723,10 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_authenticate_with_private_id_verify(d0_blind
                goto fail;
        }
 
-       if(ctx->msglen <= (size_t) *msglen)
+       if(status)
+               *status = !!d0_bignum_cmp(ctx->schnorr_4_to_s_signature, zero);
+
+       if(ctx->msglen <= *msglen)
                memcpy(msg, ctx->msg, ctx->msglen);
        else
                memcpy(msg, ctx->msg, *msglen);
@@ -630,13 +742,15 @@ fail:
 
 WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
 {
-       USING(schnorr_4_to_s);
-
+       d0_iobuf_t *out = NULL;
        static unsigned char convbuf[1024];
-       d0_iobuf_t *out = d0_iobuf_open_write(outbuf, *outbuflen);
-       d0_iobuf_t *conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
+       d0_iobuf_t *conv = NULL;
+       size_t sz, n;
 
-       size_t n, sz;
+       USING(schnorr_4_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_close(conv, &sz));
@@ -645,22 +759,51 @@ WARN_UNUSED_RESULT BOOL d0_blind_id_fingerprint64_public_id(d0_blind_id_t *ctx,
        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;
+}
+
+BOOL d0_blind_id_sessionkey_public_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
+{
+       d0_iobuf_t *out = NULL;
+       static unsigned char convbuf[1024];
+       d0_iobuf_t *conv = NULL;
+       size_t n, sz;
+
+       USING(r); USING(other_4_to_r); USING(schnorr_G);
+
+       out = d0_iobuf_open_write(outbuf, *outbuflen);
+       conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
+
+       // temps: temp0 result
+       CHECK(d0_bignum_mod_pow(temp0, ctx->other_4_to_r, ctx->r, ctx->schnorr_G));
+       CHECK(d0_iobuf_write_bignum(conv, temp0));
+       CHECK(d0_iobuf_close(conv, &sz));
+       conv = NULL;
+
+       n = *outbuflen;
+       if(n > SHA_DIGESTSIZE)
+               n = SHA_DIGESTSIZE;
+       CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
+
+       return d0_iobuf_close(out, outbuflen);
+
+fail:
+       if(conv)
+               d0_iobuf_close(conv, &sz);
+       d0_iobuf_close(out, outbuflen);
        return 0;
 }
 
-d0_blind_id_t *d0_blind_id_new()
+d0_blind_id_t *d0_blind_id_new(void)
 {
        d0_blind_id_t *b = d0_malloc(sizeof(d0_blind_id_t));
        memset(b, 0, sizeof(*b));