pySim-read.py: Enable reading of EF.IMPI from ISIM

IMS private user identity (IMPI)
As per TS1.103 version 14.2.0, this EF contains the private user identity of the user.
EF.IMPI consist of NAI TLV Data object.The NAI shall be encoded to an octet string
according to UTF-8 encoding rules as specified in IETF RFC 3629.

Reading of EF.IMPI is achieved by first selecting the ISIM application using its AID.
This is followed by selecting EF.IMPI with File ID - 6f02 in ADF.ISIM

Change-Id: I8d8e76e3f6b9ca7a0be262fee99cd5a397edbefa

pySim-read.py

@@ -315,6 +315,17 @@ if __name__ == '__main__':
 		except Exception as e:
 			print("Home Network Domain Name: Can't read file -- " + str(e))
 
+		# EF.IMPI - IMS private user identity
+		try:
+			if card.file_exists(EF_ISIM_ADF_map['IMPI']):
+				(res, sw) = card.read_impi()
+				if sw == '9000':
+					print("IMS private user identity: %s" % (len(res) and res or 'Not available',))
+				else:
+					print("IMS private user identity: Can't read, response code = %s" % (sw,))
+		except Exception as e:
+			print("IMS private user identity: Can't read file -- " + str(e))
+
 	# Check whether we have th AID of ISIM, if so select it by its AID
 	# EF.IST - File Id in ADF ISIM : 6f07
 	if '9000' == card.select_adf_by_aid(adf="isim"):

pySim/cards.py

@@ -375,6 +375,16 @@ class IsimCard(Card):
 		data, sw = self._scc.update_binary(EF_ISIM_ADF_map['DOMAIN'], rpad(content, bin_size_bytes*2))
 		return sw
 
+	def read_impi(self):
+		(res, sw) = self._scc.read_binary(EF_ISIM_ADF_map['IMPI'])
+		if sw == '9000':
+			# Skip the inital tag value ('80') byte and get length of contents
+			length = int(res[2:4], 16)
+			content = h2s(res[4:4+(length*2)])
+			return (content, sw)
+		else:
+			return (None, sw)
+
 
 class _MagicSimBase(Card):
 	"""

pysim-testdata/sysmoISIM-SJA2.ok

@@ -183,6 +183,7 @@ P-CSCF:
 	Not available
 
 Home Network Domain Name: Not available
+IMS private user identity: Not available
 ISIM Service Table: 190200
 	Service 1 - P-CSCF address
 	Service 4 - GBA-based Local Key Establishment Mechanism