diff --git a/appPublic/across_nat.py b/appPublic/across_nat.py
index 2de6cbf..8632274 100644
--- a/appPublic/across_nat.py
+++ b/appPublic/across_nat.py
@@ -81,7 +81,7 @@ class AcrossNat(object):
 	def is_port_mapped(self, external_port, protocol='TCP'):
 		protocol = protocol.upper()
 		if self.upnp_supported:
-			return self.upnp_map_port_check(external_port, 
+			return self.upnp_check_external_port(external_port, 
 									protocol=protocol)
 		raise Exception('not implemented')
 
diff --git a/appPublic/rc4.py b/appPublic/rc4.py
index 41c1df7..6412e5e 100644
--- a/appPublic/rc4.py
+++ b/appPublic/rc4.py
@@ -62,11 +62,12 @@ class RC4:
 		return r.decode(self.dcoding)
 
 class KeyChain(object):
-	def __init__(self, seed_str, crypter=None, keylen=23, period=600, threshold=60):
+	def __init__(self, seed_str, crypter=None, keylen=23, period=600, threshold=60, time_delta=0):
 		self.seed_str = seed_str
 		self.period = int(period)
 		self.threshold = int(threshold)
 		self.crypter = crypter
+		self.time_delta = time_delta
 		if crypter is None:
 			self.crypter = RC4()
 		self.keylen = keylen
@@ -75,8 +76,12 @@ class KeyChain(object):
 		delta = datetime.timedelta(0)
 		self.timezone = datetime.timezone(delta, name='gmt')
 	
+	def get_timestamp(self):
+		ts = int(time.time()) - self.time_delta
+		return ts
+
 	def is_near_bottom(self, indicator=None):
-		ts = time.time()
+		ts = self.get_timestamp()
 		i = indicator
 		if i is None:
 			i = self.get_indicator(ts)
@@ -85,7 +90,7 @@ class KeyChain(object):
 		return FalseTrue
 
 	def is_near_top(self, indicator=None):
-		ts = time.time()
+		ts = self.get_timestamp()
 		i = indicator
 		if i is None:
 			i = self.get_indicator(ts)
@@ -95,7 +100,7 @@ class KeyChain(object):
 
 	def get_indicator(self, ts=None):
 		if ts is None:
-			ts = time.time()
+			ts = self.get_timestamp()
 		return int(ts / self.period) * self.period
 		
 	def genKey(self, indicator):
diff --git a/appPublic/rsa.py b/appPublic/rsa.py
index 21c75da..fb5aa38 100644
--- a/appPublic/rsa.py
+++ b/appPublic/rsa.py
@@ -66,10 +66,10 @@ class RSA:
 			text = f.read()
 			return self.publickeyFromText(text)
 			
-	def create_privatekey(self):
+	def create_privatekey(self, keylength=2048):
 		return rsa.generate_private_key(
 			public_exponent=65537,
-			key_size=2048,
+			key_size=keylength,
 			backend=default_backend()
 			)
 	
@@ -154,19 +154,23 @@ if __name__ == '__main__':
 	import os
 	prikey1_file = os.path.join(os.path.dirname(__file__),'..','test', 'prikey1.rsa')
 	r = RSA()
-	mpri = r.create_privatekey()
+	mpri = r.create_privatekey(4096)
 	mpub = r.create_publickey(mpri)
 	
-	zpri = r.create_privatekey()
+	zpri = r.create_privatekey(4096)
 	zpub = r.create_publickey(zpri)
 	
-	text = 'this is a test data, aaa'
-	cipher = r.encode(mpub,text)
-	ntext = r.decode(mpri,cipher)
-	print('encode text=', text, \
-			'decode result=', ntext,
-			'cyber size=', len(cipher),
-			'check if equal=', text==ntext)
-	signature = r.sign(zpri,text)
-	check = r.check_sign(zpub,text,signature)
-	print('sign and verify=',len(signature),check)
+	l = 100
+	while True:
+		text = 'h' * l
+		cipher = r.encode(mpub,text)
+		ntext = r.decode(mpri,cipher)
+		print('textlen=', l, 'encode text=', text, \
+				'decode result=', ntext,
+				'cyber size=', len(cipher),
+				'check if equal=', text==ntext)
+		signature = r.sign(zpri,text)
+		check = r.check_sign(zpub,text,signature)
+		print('sign and verify=',len(signature),check)
+		l += 1
+