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-rw-r--r--openssl/demos/jpake/jpakedemo.c469
1 files changed, 469 insertions, 0 deletions
diff --git a/openssl/demos/jpake/jpakedemo.c b/openssl/demos/jpake/jpakedemo.c
new file mode 100644
index 000000000..338a8810d
--- /dev/null
+++ b/openssl/demos/jpake/jpakedemo.c
@@ -0,0 +1,469 @@
+#include "openssl/bn.h"
+#include "openssl/sha.h"
+#include <assert.h>
+#include <string.h>
+#include <stdlib.h>
+
+/* Copyright (C) 2008 Ben Laurie (ben@links.org) */
+
+/*
+ * Implement J-PAKE, as described in
+ * http://grouper.ieee.org/groups/1363/Research/contributions/hao-ryan-2008.pdf
+ *
+ * With hints from http://www.cl.cam.ac.uk/~fh240/software/JPAKE2.java.
+ */
+
+static void showbn(const char *name, const BIGNUM *bn)
+ {
+ fputs(name, stdout);
+ fputs(" = ", stdout);
+ BN_print_fp(stdout, bn);
+ putc('\n', stdout);
+ }
+
+typedef struct
+ {
+ BN_CTX *ctx; // Perhaps not the best place for this?
+ BIGNUM *p;
+ BIGNUM *q;
+ BIGNUM *g;
+ } JPakeParameters;
+
+static void JPakeParametersInit(JPakeParameters *params)
+ {
+ params->ctx = BN_CTX_new();
+
+ // For now use p, q, g from Java sample code. Later, generate them.
+ params->p = NULL;
+ BN_hex2bn(&params->p, "fd7f53811d75122952df4a9c2eece4e7f611b7523cef4400c31e3f80b6512669455d402251fb593d8d58fabfc5f5ba30f6cb9b556cd7813b801d346ff26660b76b9950a5a49f9fe8047b1022c24fbba9d7feb7c61bf83b57e7c6a8a6150f04fb83f6d3c51ec3023554135a169132f675f3ae2b61d72aeff22203199dd14801c7");
+ params->q = NULL;
+ BN_hex2bn(&params->q, "9760508f15230bccb292b982a2eb840bf0581cf5");
+ params->g = NULL;
+ BN_hex2bn(&params->g, "f7e1a085d69b3ddecbbcab5c36b857b97994afbbfa3aea82f9574c0b3d0782675159578ebad4594fe67107108180b449167123e84c281613b7cf09328cc8a6e13c167a8b547c8d28e0a3ae1e2bb3a675916ea37f0bfa213562f1fb627a01243bcca4f1bea8519089a883dfe15ae59f06928b665e807b552564014c3bfecf492a");
+
+ showbn("p", params->p);
+ showbn("q", params->q);
+ showbn("g", params->g);
+ }
+
+typedef struct
+ {
+ BIGNUM *gr; // g^r (r random)
+ BIGNUM *b; // b = r - x*h, h=hash(g, g^r, g^x, name)
+ } JPakeZKP;
+
+typedef struct
+ {
+ BIGNUM *gx; // g^x
+ JPakeZKP zkpx; // ZKP(x)
+ } JPakeStep1;
+
+typedef struct
+ {
+ BIGNUM *X; // g^(xa + xc + xd) * xb * s
+ JPakeZKP zkpxbs; // ZKP(xb * s)
+ } JPakeStep2;
+
+typedef struct
+ {
+ const char *name; // Must be unique
+ int base; // 1 for Alice, 3 for Bob. Only used for printing stuff.
+ JPakeStep1 s1c; // Alice's g^x3, ZKP(x3) or Bob's g^x1, ZKP(x1)
+ JPakeStep1 s1d; // Alice's g^x4, ZKP(x4) or Bob's g^x2, ZKP(x2)
+ JPakeStep2 s2; // Alice's A, ZKP(x2 * s) or Bob's B, ZKP(x4 * s)
+ } JPakeUserPublic;
+
+/*
+ * The user structure. In the definition, (xa, xb, xc, xd) are Alice's
+ * (x1, x2, x3, x4) or Bob's (x3, x4, x1, x2). If you see what I mean.
+ */
+typedef struct
+ {
+ JPakeUserPublic p;
+ BIGNUM *secret; // The shared secret
+ BIGNUM *key; // The calculated (shared) key
+ BIGNUM *xa; // Alice's x1 or Bob's x3
+ BIGNUM *xb; // Alice's x2 or Bob's x4
+ } JPakeUser;
+
+// Generate each party's random numbers. xa is in [0, q), xb is in [1, q).
+static void genrand(JPakeUser *user, const JPakeParameters *params)
+ {
+ BIGNUM *qm1;
+
+ // xa in [0, q)
+ user->xa = BN_new();
+ BN_rand_range(user->xa, params->q);
+
+ // q-1
+ qm1 = BN_new();
+ BN_copy(qm1, params->q);
+ BN_sub_word(qm1, 1);
+
+ // ... and xb in [0, q-1)
+ user->xb = BN_new();
+ BN_rand_range(user->xb, qm1);
+ // [1, q)
+ BN_add_word(user->xb, 1);
+
+ // cleanup
+ BN_free(qm1);
+
+ // Show
+ printf("x%d", user->p.base);
+ showbn("", user->xa);
+ printf("x%d", user->p.base+1);
+ showbn("", user->xb);
+ }
+
+static void hashlength(SHA_CTX *sha, size_t l)
+ {
+ unsigned char b[2];
+
+ assert(l <= 0xffff);
+ b[0] = l >> 8;
+ b[1] = l&0xff;
+ SHA1_Update(sha, b, 2);
+ }
+
+static void hashstring(SHA_CTX *sha, const char *string)
+ {
+ size_t l = strlen(string);
+
+ hashlength(sha, l);
+ SHA1_Update(sha, string, l);
+ }
+
+static void hashbn(SHA_CTX *sha, const BIGNUM *bn)
+ {
+ size_t l = BN_num_bytes(bn);
+ unsigned char *bin = alloca(l);
+
+ hashlength(sha, l);
+ BN_bn2bin(bn, bin);
+ SHA1_Update(sha, bin, l);
+ }
+
+// h=hash(g, g^r, g^x, name)
+static void zkpHash(BIGNUM *h, const JPakeZKP *zkp, const BIGNUM *gx,
+ const JPakeUserPublic *from, const JPakeParameters *params)
+ {
+ unsigned char md[SHA_DIGEST_LENGTH];
+ SHA_CTX sha;
+
+ // XXX: hash should not allow moving of the boundaries - Java code
+ // is flawed in this respect. Length encoding seems simplest.
+ SHA1_Init(&sha);
+ hashbn(&sha, params->g);
+ hashbn(&sha, zkp->gr);
+ hashbn(&sha, gx);
+ hashstring(&sha, from->name);
+ SHA1_Final(md, &sha);
+ BN_bin2bn(md, SHA_DIGEST_LENGTH, h);
+ }
+
+// Prove knowledge of x
+// Note that we don't send g^x because, as it happens, we've always
+// sent it elsewhere. Also note that because of that, we could avoid
+// calculating it here, but we don't, for clarity...
+static void CreateZKP(JPakeZKP *zkp, const BIGNUM *x, const JPakeUser *us,
+ const BIGNUM *zkpg, const JPakeParameters *params,
+ int n, const char *suffix)
+ {
+ BIGNUM *r = BN_new();
+ BIGNUM *gx = BN_new();
+ BIGNUM *h = BN_new();
+ BIGNUM *t = BN_new();
+
+ // r in [0,q)
+ // XXX: Java chooses r in [0, 2^160) - i.e. distribution not uniform
+ BN_rand_range(r, params->q);
+ // g^r
+ zkp->gr = BN_new();
+ BN_mod_exp(zkp->gr, zkpg, r, params->p, params->ctx);
+ // g^x
+ BN_mod_exp(gx, zkpg, x, params->p, params->ctx);
+
+ // h=hash...
+ zkpHash(h, zkp, gx, &us->p, params);
+
+ // b = r - x*h
+ BN_mod_mul(t, x, h, params->q, params->ctx);
+ zkp->b = BN_new();
+ BN_mod_sub(zkp->b, r, t, params->q, params->ctx);
+
+ // show
+ printf(" ZKP(x%d%s)\n", n, suffix);
+ showbn(" zkpg", zkpg);
+ showbn(" g^x", gx);
+ showbn(" g^r", zkp->gr);
+ showbn(" b", zkp->b);
+
+ // cleanup
+ BN_free(t);
+ BN_free(h);
+ BN_free(gx);
+ BN_free(r);
+ }
+
+static int VerifyZKP(const JPakeZKP *zkp, BIGNUM *gx,
+ const JPakeUserPublic *them, const BIGNUM *zkpg,
+ const JPakeParameters *params, int n, const char *suffix)
+ {
+ BIGNUM *h = BN_new();
+ BIGNUM *t1 = BN_new();
+ BIGNUM *t2 = BN_new();
+ BIGNUM *t3 = BN_new();
+ int ret = 0;
+
+ zkpHash(h, zkp, gx, them, params);
+
+ // t1 = g^b
+ BN_mod_exp(t1, zkpg, zkp->b, params->p, params->ctx);
+ // t2 = (g^x)^h = g^{hx}
+ BN_mod_exp(t2, gx, h, params->p, params->ctx);
+ // t3 = t1 * t2 = g^{hx} * g^b = g^{hx+b} = g^r (allegedly)
+ BN_mod_mul(t3, t1, t2, params->p, params->ctx);
+
+ printf(" ZKP(x%d%s)\n", n, suffix);
+ showbn(" zkpg", zkpg);
+ showbn(" g^r'", t3);
+
+ // verify t3 == g^r
+ if(BN_cmp(t3, zkp->gr) == 0)
+ ret = 1;
+
+ // cleanup
+ BN_free(t3);
+ BN_free(t2);
+ BN_free(t1);
+ BN_free(h);
+
+ if(ret)
+ puts(" OK");
+ else
+ puts(" FAIL");
+
+ return ret;
+ }
+
+static void sendstep1_substep(JPakeStep1 *s1, const BIGNUM *x,
+ const JPakeUser *us,
+ const JPakeParameters *params, int n)
+ {
+ s1->gx = BN_new();
+ BN_mod_exp(s1->gx, params->g, x, params->p, params->ctx);
+ printf(" g^{x%d}", n);
+ showbn("", s1->gx);
+
+ CreateZKP(&s1->zkpx, x, us, params->g, params, n, "");
+ }
+
+static void sendstep1(const JPakeUser *us, JPakeUserPublic *them,
+ const JPakeParameters *params)
+ {
+ printf("\n%s sends %s:\n\n", us->p.name, them->name);
+
+ // from's g^xa (which becomes to's g^xc) and ZKP(xa)
+ sendstep1_substep(&them->s1c, us->xa, us, params, us->p.base);
+ // from's g^xb (which becomes to's g^xd) and ZKP(xb)
+ sendstep1_substep(&them->s1d, us->xb, us, params, us->p.base+1);
+ }
+
+static int verifystep1(const JPakeUser *us, const JPakeUserPublic *them,
+ const JPakeParameters *params)
+ {
+ printf("\n%s verifies %s:\n\n", us->p.name, them->name);
+
+ // verify their ZKP(xc)
+ if(!VerifyZKP(&us->p.s1c.zkpx, us->p.s1c.gx, them, params->g, params,
+ them->base, ""))
+ return 0;
+
+ // verify their ZKP(xd)
+ if(!VerifyZKP(&us->p.s1d.zkpx, us->p.s1d.gx, them, params->g, params,
+ them->base+1, ""))
+ return 0;
+
+ // g^xd != 1
+ printf(" g^{x%d} != 1: ", them->base+1);
+ if(BN_is_one(us->p.s1d.gx))
+ {
+ puts("FAIL");
+ return 0;
+ }
+ puts("OK");
+
+ return 1;
+ }
+
+static void sendstep2(const JPakeUser *us, JPakeUserPublic *them,
+ const JPakeParameters *params)
+ {
+ BIGNUM *t1 = BN_new();
+ BIGNUM *t2 = BN_new();
+
+ printf("\n%s sends %s:\n\n", us->p.name, them->name);
+
+ // X = g^{(xa + xc + xd) * xb * s}
+ // t1 = g^xa
+ BN_mod_exp(t1, params->g, us->xa, params->p, params->ctx);
+ // t2 = t1 * g^{xc} = g^{xa} * g^{xc} = g^{xa + xc}
+ BN_mod_mul(t2, t1, us->p.s1c.gx, params->p, params->ctx);
+ // t1 = t2 * g^{xd} = g^{xa + xc + xd}
+ BN_mod_mul(t1, t2, us->p.s1d.gx, params->p, params->ctx);
+ // t2 = xb * s
+ BN_mod_mul(t2, us->xb, us->secret, params->q, params->ctx);
+ // X = t1^{t2} = t1^{xb * s} = g^{(xa + xc + xd) * xb * s}
+ them->s2.X = BN_new();
+ BN_mod_exp(them->s2.X, t1, t2, params->p, params->ctx);
+
+ // Show
+ printf(" g^{(x%d + x%d + x%d) * x%d * s)", us->p.base, them->base,
+ them->base+1, us->p.base+1);
+ showbn("", them->s2.X);
+
+ // ZKP(xb * s)
+ // XXX: this is kinda funky, because we're using
+ //
+ // g' = g^{xa + xc + xd}
+ //
+ // as the generator, which means X is g'^{xb * s}
+ CreateZKP(&them->s2.zkpxbs, t2, us, t1, params, us->p.base+1, " * s");
+
+ // cleanup
+ BN_free(t1);
+ BN_free(t2);
+ }
+
+static int verifystep2(const JPakeUser *us, const JPakeUserPublic *them,
+ const JPakeParameters *params)
+ {
+ BIGNUM *t1 = BN_new();
+ BIGNUM *t2 = BN_new();
+ int ret = 0;
+
+ printf("\n%s verifies %s:\n\n", us->p.name, them->name);
+
+ // g' = g^{xc + xa + xb} [from our POV]
+ // t1 = xa + xb
+ BN_mod_add(t1, us->xa, us->xb, params->q, params->ctx);
+ // t2 = g^{t1} = g^{xa+xb}
+ BN_mod_exp(t2, params->g, t1, params->p, params->ctx);
+ // t1 = g^{xc} * t2 = g^{xc + xa + xb}
+ BN_mod_mul(t1, us->p.s1c.gx, t2, params->p, params->ctx);
+
+ if(VerifyZKP(&us->p.s2.zkpxbs, us->p.s2.X, them, t1, params, them->base+1,
+ " * s"))
+ ret = 1;
+
+ // cleanup
+ BN_free(t2);
+ BN_free(t1);
+
+ return ret;
+ }
+
+static void computekey(JPakeUser *us, const JPakeParameters *params)
+ {
+ BIGNUM *t1 = BN_new();
+ BIGNUM *t2 = BN_new();
+ BIGNUM *t3 = BN_new();
+
+ printf("\n%s calculates the shared key:\n\n", us->p.name);
+
+ // K = (X/g^{xb * xd * s})^{xb}
+ // = (g^{(xc + xa + xb) * xd * s - xb * xd *s})^{xb}
+ // = (g^{(xa + xc) * xd * s})^{xb}
+ // = g^{(xa + xc) * xb * xd * s}
+ // [which is the same regardless of who calculates it]
+
+ // t1 = (g^{xd})^{xb} = g^{xb * xd}
+ BN_mod_exp(t1, us->p.s1d.gx, us->xb, params->p, params->ctx);
+ // t2 = -s = q-s
+ BN_sub(t2, params->q, us->secret);
+ // t3 = t1^t2 = g^{-xb * xd * s}
+ BN_mod_exp(t3, t1, t2, params->p, params->ctx);
+ // t1 = X * t3 = X/g^{xb * xd * s}
+ BN_mod_mul(t1, us->p.s2.X, t3, params->p, params->ctx);
+ // K = t1^{xb}
+ us->key = BN_new();
+ BN_mod_exp(us->key, t1, us->xb, params->p, params->ctx);
+
+ // show
+ showbn(" K", us->key);
+
+ // cleanup
+ BN_free(t3);
+ BN_free(t2);
+ BN_free(t1);
+ }
+
+int main(int argc, char **argv)
+ {
+ JPakeParameters params;
+ JPakeUser alice, bob;
+
+ alice.p.name = "Alice";
+ alice.p.base = 1;
+ bob.p.name = "Bob";
+ bob.p.base = 3;
+
+ JPakeParametersInit(&params);
+
+ // Shared secret
+ alice.secret = BN_new();
+ BN_rand(alice.secret, 32, -1, 0);
+ bob.secret = alice.secret;
+ showbn("secret", alice.secret);
+
+ assert(BN_cmp(alice.secret, params.q) < 0);
+
+ // Alice's x1, x2
+ genrand(&alice, &params);
+
+ // Bob's x3, x4
+ genrand(&bob, &params);
+
+ // Now send stuff to each other...
+ sendstep1(&alice, &bob.p, &params);
+ sendstep1(&bob, &alice.p, &params);
+
+ // And verify what each other sent
+ if(!verifystep1(&alice, &bob.p, &params))
+ return 1;
+ if(!verifystep1(&bob, &alice.p, &params))
+ return 2;
+
+ // Second send
+ sendstep2(&alice, &bob.p, &params);
+ sendstep2(&bob, &alice.p, &params);
+
+ // And second verify
+ if(!verifystep2(&alice, &bob.p, &params))
+ return 3;
+ if(!verifystep2(&bob, &alice.p, &params))
+ return 4;
+
+ // Compute common key
+ computekey(&alice, &params);
+ computekey(&bob, &params);
+
+ // Confirm the common key is identical
+ // XXX: if the two secrets are not the same, everything works up
+ // to this point, so the only way to detect a failure is by the
+ // difference in the calculated keys.
+ // Since we're all the same code, just compare them directly. In a
+ // real system, Alice sends Bob H(H(K)), Bob checks it, then sends
+ // back H(K), which Alice checks, or something equivalent.
+ puts("\nAlice and Bob check keys are the same:");
+ if(BN_cmp(alice.key, bob.key) == 0)
+ puts(" OK");
+ else
+ {
+ puts(" FAIL");
+ return 5;
+ }
+
+ return 0;
+ }
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