reworked zero-padding machinery and added one more instance of zero-padding

3 files changed, 20 insertions, 14 deletions

diff --git a/lib/consumer.cc b/lib/consumer.cc
index 12866f0..282f0cc 100644
--- a/lib/consumer.cc
+++ b/lib/consumer.cc
@@ -99,15 +99,16 @@ namespace opkele {
             secret.from_base64(p.get_param("mac_key"));
         }else{
             util::bignum_t s_pub = util::base64_to_bignum(p.get_param("dh_server_public"));
-            vector<unsigned char> ck(DH_size(dh));
-            int cklen = DH_compute_key(&(ck.front()),s_pub,dh);
+            vector<unsigned char> ck(DH_size(dh)+1);
+            unsigned char *ckptr = &(ck.front())+1;
+            int cklen = DH_compute_key(ckptr,s_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);
+            if(cklen && (*ckptr)&0x80) {
+                (*(--ckptr)) = 0; ++cklen;
+            }
             unsigned char key_sha1[SHA_DIGEST_LENGTH];
-            SHA1(&(ck.front()),ck.size(),key_sha1);
+            SHA1(ckptr,cklen,key_sha1);
             secret.enxor_from_base64(key_sha1,p.get_param("enc_mac_key"));
         }
         int expires_in = 0;
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);
diff --git a/lib/util.cc b/lib/util.cc
index d9abca7..94f6f53 100644
--- a/lib/util.cc
+++ b/lib/util.cc
@@ -86,9 +86,13 @@ namespace opkele {
         }
 
         string bignum_to_base64(const BIGNUM *bn) {
-            vector<unsigned char> bin(BN_num_bytes(bn));
-            int l = BN_bn2bin(bn,&(bin.front()));
-            return encode_base64(&(bin.front()),l);
+            vector<unsigned char> bin(BN_num_bytes(bn)+1);
+            unsigned char *binptr = &(bin.front())+1;
+            int l = BN_bn2bin(bn,binptr);
+            if(l && (*binptr)&0x80){
+                (*(--binptr)) = 0; ++l;
+            }
+            return encode_base64(binptr,l);
         }
 
         /*