1 files changed, 6 insertions, 5 deletions

diff --git a/lib/server.cc b/lib/server.cc
index e81d4b6..8db97be 100644
--- a/lib/server.cc
+++ b/lib/server.cc
@@ -34,14 +34,15 @@ namespace opkele {
                 dh->g = util::dec_to_bignum(data::_default_g);
             if(!DH_generate_key(dh))
                 throw exception_openssl(OPKELE_CP_ "failed to DH_generate_key()");
-            vector<unsigned char> ck(DH_size(dh));
+            vector<unsigned char> ck(DH_size(dh)+1);
+            unsigned char *ckptr = &(ck.front())+1;
             int cklen = DH_compute_key(&(ck.front()),c_pub,dh);
             if(cklen<0)
                 throw exception_openssl(OPKELE_CP_ "failed to DH_compute_key()");
-            ck.resize(cklen);
-            // OpenID algorithm requires extra zero in case of set bit here
-            if(ck[0]&0x80) ck.insert(ck.begin(),1,0);
-            SHA1(&(ck.front()),ck.size(),key_sha1);
+            if(cklen && (*ckptr)&0x80) {
+                (*(--ckptr)) = 0; ++cklen;
+            }
+            SHA1(ckptr,cklen,key_sha1);
             st = sess_dh_sha1;
         }
         assoc_t assoc = alloc_assoc(mode_associate);