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
@@ -94,25 +94,26 @@ namespace opkele {
 	if(p.has_param("session_type")) st = p.get_param("session_type");
 	if((!st.empty()) && st!="DH-SHA1")
 	    throw bad_input(OPKELE_CP_ "unsupported session_type");
 	secret_t secret;
 	if(st.empty()) {
 	    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;
 	if(p.has_param("expires_in")) {
 	    expires_in = util::string_to_long(p.get_param("expires_in"));
 	}else if(p.has_param("issued") && p.has_param("expiry")) {
 	    expires_in = util::w3c_to_time(p.get_param("expiry"))-util::w3c_to_time(p.get_param("issued"));
 	}else
diff --git a/lib/server.cc b/lib/server.cc
index e81d4b6..8db97be 100644
--- a/lib/server.cc
+++ b/lib/server.cc
@@ -29,24 +29,25 @@ namespace opkele {
 	    else
 		dh->p = util::dec_to_bignum(data::_default_p);
 	    if(pin.has_param("openid.dh_gen"))
 		dh->g = util::base64_to_bignum(pin.get_param("openid.dh_gen"));
 	    else
 		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);
 	time_t now = time(0);
 	pout.clear();
 	pout["assoc_type"] = assoc->assoc_type();
 	pout["assoc_handle"] = assoc->handle();
 	/* TODO: eventually remove deprecated stuff */
diff --git a/lib/util.cc b/lib/util.cc
index d9abca7..94f6f53 100644
--- a/lib/util.cc
+++ b/lib/util.cc
@@ -81,19 +81,23 @@ namespace opkele {
 	BIGNUM *dec_to_bignum(const string& dec) {
 	    BIGNUM *rv = 0;
 	    if(!BN_dec2bn(&rv,dec.c_str()))
 		throw failed_conversion(OPKELE_CP_ "failed to BN_dec2bn()");
 	    return rv;
 	}
 
 	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);
 	}
 
 	/*
 	 * w3c times
 	 */
 
 	string time_to_w3c(time_t t) {
 	    struct tm tm_t;