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Fixes from HEAD.

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This commit is contained in:
Dr. Stephen Henson
2008-10-27 12:04:04 +00:00
parent 2124e869a8
commit c10f53a897
5 changed files with 121 additions and 92 deletions
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142
crypto/jpake/jpake.c
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@@ -13,23 +13,23 @@
typedef struct
{
char *name; // Must be unique
char *name; /* Must be unique */
char *peer_name;
BIGNUM *p;
BIGNUM *g;
BIGNUM *q;
BIGNUM *gxc; // Alice's g^{x3} or Bob's g^{x1}
BIGNUM *gxd; // Alice's g^{x4} or Bob's g^{x2}
BIGNUM *gxc; /* Alice's g^{x3} or Bob's g^{x1} */
BIGNUM *gxd; /* Alice's g^{x4} or Bob's g^{x2} */
} JPAKE_CTX_PUBLIC;
struct JPAKE_CTX
{
JPAKE_CTX_PUBLIC p;
BIGNUM *secret; // The shared secret
BIGNUM *secret; /* The shared secret */
BN_CTX *ctx;
BIGNUM *xa; // Alice's x1 or Bob's x3
BIGNUM *xb; // Alice's x2 or Bob's x4
BIGNUM *key; // The calculated (shared) key
BIGNUM *xa; /* Alice's x1 or Bob's x3 */
BIGNUM *xb; /* Alice's x2 or Bob's x4 */
BIGNUM *key; /* The calculated (shared) key */
};
static void JPAKE_ZKP_init(JPAKE_ZKP *zkp)
@@ -44,7 +44,7 @@ static void JPAKE_ZKP_release(JPAKE_ZKP *zkp)
BN_free(zkp->gr);
}
// Two birds with one stone - make the global name as expected
/* Two birds with one stone - make the global name as expected */
#define JPAKE_STEP_PART_init JPAKE_STEP2_init
#define JPAKE_STEP_PART_release JPAKE_STEP2_release
@@ -158,15 +158,17 @@ static void hashbn(SHA_CTX *sha, const BIGNUM *bn)
SHA1_Update(sha, bin, l);
}
// h=hash(g, g^r, g^x, name)
/* h=hash(g, g^r, g^x, name) */
static void zkp_hash(BIGNUM *h, const BIGNUM *zkpg, const JPAKE_STEP_PART *p,
const char *proof_name)
{
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.
/*
* 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, zkpg);
assert(!BN_is_zero(p->zkpx.gr));
@@ -177,8 +179,10 @@ static void zkp_hash(BIGNUM *h, const BIGNUM *zkpg, const JPAKE_STEP_PART *p,
BN_bin2bn(md, SHA_DIGEST_LENGTH, h);
}
// Prove knowledge of x
// Note that p->gx has already been calculated
/*
* Prove knowledge of x
* Note that p->gx has already been calculated
*/
static void generate_zkp(JPAKE_STEP_PART *p, const BIGNUM *x,
const BIGNUM *zkpg, JPAKE_CTX *ctx)
{
@@ -186,20 +190,22 @@ static void generate_zkp(JPAKE_STEP_PART *p, const BIGNUM *x,
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
/*
* r in [0,q)
* XXX: Java chooses r in [0, 2^160) - i.e. distribution not uniform
*/
BN_rand_range(r, ctx->p.q);
// g^r
/* g^r */
BN_mod_exp(p->zkpx.gr, zkpg, r, ctx->p.p, ctx->ctx);
// h=hash...
/* h=hash... */
zkp_hash(h, zkpg, p, ctx->p.name);
// b = r - x*h
/* b = r - x*h */
BN_mod_mul(t, x, h, ctx->p.q, ctx->ctx);
BN_mod_sub(p->zkpx.b, r, t, ctx->p.q, ctx->ctx);
// cleanup
/* cleanup */
BN_free(t);
BN_free(h);
BN_free(r);
@@ -216,20 +222,20 @@ static int verify_zkp(const JPAKE_STEP_PART *p, const BIGNUM *zkpg,
zkp_hash(h, zkpg, p, ctx->p.peer_name);
// t1 = g^b
/* t1 = g^b */
BN_mod_exp(t1, zkpg, p->zkpx.b, ctx->p.p, ctx->ctx);
// t2 = (g^x)^h = g^{hx}
/* t2 = (g^x)^h = g^{hx} */
BN_mod_exp(t2, p->gx, h, ctx->p.p, ctx->ctx);
// t3 = t1 * t2 = g^{hx} * g^b = g^{hx+b} = g^r (allegedly)
/* t3 = t1 * t2 = g^{hx} * g^b = g^{hx+b} = g^r (allegedly) */
BN_mod_mul(t3, t1, t2, ctx->p.p, ctx->ctx);
// verify t3 == g^r
/* verify t3 == g^r */
if(BN_cmp(t3, p->zkpx.gr) == 0)
ret = 1;
else
JPAKEerr(JPAKE_F_VERIFY_ZKP, JPAKE_R_ZKP_VERIFY_FAILED);
// cleanup
/* cleanup */
BN_free(t3);
BN_free(t2);
BN_free(t1);
@@ -245,25 +251,25 @@ static void generate_step_part(JPAKE_STEP_PART *p, const BIGNUM *x,
generate_zkp(p, x, g, ctx);
}
// Generate each party's random numbers. xa is in [0, q), xb is in [1, q).
/* Generate each party's random numbers. xa is in [0, q), xb is in [1, q). */
static void genrand(JPAKE_CTX *ctx)
{
BIGNUM *qm1;
// xa in [0, q)
/* xa in [0, q) */
BN_rand_range(ctx->xa, ctx->p.q);
// q-1
/* q-1 */
qm1 = BN_new();
BN_copy(qm1, ctx->p.q);
BN_sub_word(qm1, 1);
// ... and xb in [0, q-1)
/* ... and xb in [0, q-1) */
BN_rand_range(ctx->xb, qm1);
// [1, q)
/* [1, q) */
BN_add_word(ctx->xb, 1);
// cleanup
/* cleanup */
BN_free(qm1);
}
@@ -278,28 +284,28 @@ int JPAKE_STEP1_generate(JPAKE_STEP1 *send, JPAKE_CTX *ctx)
int JPAKE_STEP1_process(JPAKE_CTX *ctx, const JPAKE_STEP1 *received)
{
// verify their ZKP(xc)
/* verify their ZKP(xc) */
if(!verify_zkp(&received->p1, ctx->p.g, ctx))
{
JPAKEerr(JPAKE_F_JPAKE_STEP1_PROCESS, JPAKE_R_VERIFY_X3_FAILED);
return 0;
}
// verify their ZKP(xd)
/* verify their ZKP(xd) */
if(!verify_zkp(&received->p2, ctx->p.g, ctx))
{
JPAKEerr(JPAKE_F_JPAKE_STEP1_PROCESS, JPAKE_R_VERIFY_X4_FAILED);
return 0;
}
// g^xd != 1
/* g^xd != 1 */
if(BN_is_one(received->p2.gx))
{
JPAKEerr(JPAKE_F_JPAKE_STEP1_PROCESS, JPAKE_R_G_TO_THE_X4_IS_ONE);
return 0;
}
// Save the bits we need for later
/* Save the bits we need for later */
BN_copy(ctx->p.gxc, received->p1.gx);
BN_copy(ctx->p.gxd, received->p2.gx);
@@ -312,57 +318,63 @@ int JPAKE_STEP2_generate(JPAKE_STEP2 *send, JPAKE_CTX *ctx)
BIGNUM *t1 = BN_new();
BIGNUM *t2 = BN_new();
// X = g^{(xa + xc + xd) * xb * s}
// t1 = g^xa
/*
* X = g^{(xa + xc + xd) * xb * s}
* t1 = g^xa
*/
BN_mod_exp(t1, ctx->p.g, ctx->xa, ctx->p.p, ctx->ctx);
// t2 = t1 * g^{xc} = g^{xa} * g^{xc} = g^{xa + xc}
/* t2 = t1 * g^{xc} = g^{xa} * g^{xc} = g^{xa + xc} */
BN_mod_mul(t2, t1, ctx->p.gxc, ctx->p.p, ctx->ctx);
// t1 = t2 * g^{xd} = g^{xa + xc + xd}
/* t1 = t2 * g^{xd} = g^{xa + xc + xd} */
BN_mod_mul(t1, t2, ctx->p.gxd, ctx->p.p, ctx->ctx);
// t2 = xb * s
/* t2 = xb * s */
BN_mod_mul(t2, ctx->xb, ctx->secret, ctx->p.q, ctx->ctx);
// 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}
// X = t1^{t2} = t1^{xb * s} = g^{(xa + xc + xd) * xb * s}
/*
* 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}
* X = t1^{t2} = t1^{xb * s} = g^{(xa + xc + xd) * xb * s}
*/
generate_step_part(send, t2, t1, ctx);
// cleanup
/* cleanup */
BN_free(t1);
BN_free(t2);
return 1;
}
// gx = g^{xc + xa + xb} * xd * s
/* gx = g^{xc + xa + xb} * xd * s */
static int compute_key(JPAKE_CTX *ctx, const BIGNUM *gx)
{
BIGNUM *t1 = BN_new();
BIGNUM *t2 = BN_new();
BIGNUM *t3 = BN_new();
// K = (gx/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]
/*
* K = (gx/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}
/* t1 = (g^{xd})^{xb} = g^{xb * xd} */
BN_mod_exp(t1, ctx->p.gxd, ctx->xb, ctx->p.p, ctx->ctx);
// t2 = -s = q-s
/* t2 = -s = q-s */
BN_sub(t2, ctx->p.q, ctx->secret);
// t3 = t1^t2 = g^{-xb * xd * s}
/* t3 = t1^t2 = g^{-xb * xd * s} */
BN_mod_exp(t3, t1, t2, ctx->p.p, ctx->ctx);
// t1 = gx * t3 = X/g^{xb * xd * s}
/* t1 = gx * t3 = X/g^{xb * xd * s} */
BN_mod_mul(t1, gx, t3, ctx->p.p, ctx->ctx);
// K = t1^{xb}
/* K = t1^{xb} */
BN_mod_exp(ctx->key, t1, ctx->xb, ctx->p.p, ctx->ctx);
// cleanup
/* cleanup */
BN_free(t3);
BN_free(t2);
BN_free(t1);
@@ -376,12 +388,14 @@ int JPAKE_STEP2_process(JPAKE_CTX *ctx, const JPAKE_STEP2 *received)
BIGNUM *t2 = BN_new();
int ret = 0;
// g' = g^{xc + xa + xb} [from our POV]
// t1 = xa + xb
/*
* g' = g^{xc + xa + xb} [from our POV]
* t1 = xa + xb
*/
BN_mod_add(t1, ctx->xa, ctx->xb, ctx->p.q, ctx->ctx);
// t2 = g^{t1} = g^{xa+xb}
/* t2 = g^{t1} = g^{xa+xb} */
BN_mod_exp(t2, ctx->p.g, t1, ctx->p.p, ctx->ctx);
// t1 = g^{xc} * t2 = g^{xc + xa + xb}
/* t1 = g^{xc} * t2 = g^{xc + xa + xb} */
BN_mod_mul(t1, ctx->p.gxc, t2, ctx->p.p, ctx->ctx);
if(verify_zkp(received, t1, ctx))
@@ -391,7 +405,7 @@ int JPAKE_STEP2_process(JPAKE_CTX *ctx, const JPAKE_STEP2 *received)
compute_key(ctx, received->gx);
// cleanup
/* cleanup */
BN_free(t2);
BN_free(t1);