+/* g^x is a legal value */
+static int is_legal(const BIGNUM *gx, const JPAKE_CTX *ctx)
+ {
+ BIGNUM *t;
+ int res;
+
+ if(BN_is_negative(gx) || BN_is_zero(gx) || BN_cmp(gx, ctx->p.p) >= 0)
+ return 0;
+
+ t = BN_new();
+ BN_mod_exp(t, gx, ctx->p.q, ctx->p.p, ctx->ctx);
+ res = BN_is_one(t);
+ BN_free(t);
+
+ return res;
+ }
+