add contrib/es9p_client: Perform ES9+ client functions like LPA+eUICC

This tool can be used to test the SM-DP+. It implements the full dance
of all HTTPs API operations to get to the downloadProfile, and will
decrypt the BPP to the UPP, which is then subsequently stored as file on
disk.

Needless to say, this will only work if you have an eUICC certificate +
private key that is compatible with the CI of your SM-DP+.

Change-Id: Idf8881e82f9835f5221c58b78ced9937cf5fb520

pySim/esim/es8p.py

@@ -17,7 +17,11 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 from typing import Dict, List, Optional
-from pySim.utils import b2h, h2b, bertlv_encode_tag, bertlv_encode_len
+
+from cryptography.hazmat.primitives.asymmetric import ec
+
+from pySim.utils import b2h, h2b, bertlv_encode_tag, bertlv_encode_len, bertlv_parse_one_rawtag
+from pySim.utils import bertlv_return_one_rawtlv
 
 import pySim.esim.rsp as rsp
 from pySim.esim.bsp import BspInstance
@@ -183,3 +187,79 @@ class BoundProfilePackage(ProfilePackage):
 
         # manual DER encode: wrap in outer SEQUENCE
         return bertlv_encode_tag(0xbf36) + bertlv_encode_len(len(bpp_seq)) + bpp_seq
+
+    def decode(self, euicc_ot, eid: str, bpp_bin: bytes):
+        """Decode a BPP into the PPP and subsequently UPP. This is what happens inside an eUICC."""
+
+        def split_bertlv_sequence(sequence: bytes) -> List[bytes]:
+            remainder = sequence
+            ret = []
+            while remainder:
+                _tag, _l, tlv, remainder = bertlv_return_one_rawtlv(remainder)
+                ret.append(tlv)
+            return ret
+
+        # we don't use rsp.asn1.decode('boundProfilePackage') here, as the BSP needs
+        # fully encoded + MACed TLVs including their tag + length values.
+        #bpp = rsp.asn1.decode('BoundProfilePackage', bpp_bin)
+
+        tag, _l, v, _remainder = bertlv_parse_one_rawtag(bpp_bin)
+        if len(_remainder):
+            raise ValueError('Excess data at end of TLV')
+        if tag != 0xbf36:
+            raise ValueError('Unexpected outer tag: %s' % tag)
+
+        # InitialiseSecureChannelRequest
+        tag, _l, iscr_bin, remainder = bertlv_return_one_rawtlv(v)
+        iscr = rsp.asn1.decode('InitialiseSecureChannelRequest', iscr_bin)
+
+        # configureIsdpRequest
+        tag, _l, firstSeqOf87, remainder = bertlv_parse_one_rawtag(remainder)
+        if tag != 0xa0:
+            raise ValueError("Unexpected 'firstSequenceOf87' tag: %s" % tag)
+        firstSeqOf87 = split_bertlv_sequence(firstSeqOf87)
+
+        # storeMetadataRequest
+        tag, _l, seqOf88, remainder = bertlv_parse_one_rawtag(remainder)
+        if tag != 0xa1:
+            raise ValueError("Unexpected 'sequenceOf88' tag: %s" % tag)
+        seqOf88 = split_bertlv_sequence(seqOf88)
+
+        tag, _l, tlv, remainder = bertlv_parse_one_rawtag(remainder)
+        if tag == 0xa2:
+            secondSeqOf87 = split_bertlv_sequence(tlv)
+            tag2, _l, seqOf86, remainder = bertlv_parse_one_rawtag(remainder)
+            if tag2 != 0xa3:
+                raise ValueError("Unexpected 'sequenceOf86' tag: %s" % tag)
+            seqOf86 = split_bertlv_sequence(seqOf86)
+        elif tag == 0xa3:
+            secondSeqOf87 = None
+            seqOf86 = split_bertlv_sequence(tlv)
+        else:
+            raise ValueError("Unexpected 'secondSequenceOf87' tag: %s" % tag)
+
+        # extract smdoOtpk from initialiseSecureChannel
+        smdp_otpk = iscr['smdpOtpk']
+
+        # Generate Session Keys using the CRT, opPK.DP.ECKA and otSK.EUICC.ECKA according to annex G
+        smdp_public_key = ec.EllipticCurvePublicKey.from_encoded_point(euicc_ot.curve, smdp_otpk)
+        self.shared_secret = euicc_ot.exchange(ec.ECDH(), smdp_public_key)
+
+        crt = iscr['controlRefTemplate']
+        bsp = BspInstance.from_kdf(self.shared_secret, int.from_bytes(crt['keyType'], 'big'), int.from_bytes(crt['keyLen'], 'big'), crt['hostId'], h2b(eid))
+
+        self.encoded_configureISDPRequest = bsp.demac_and_decrypt(firstSeqOf87)
+        self.configureISDPRequest = rsp.asn1.decode('ConfigureISDPRequest', self.encoded_configureISDPRequest)
+
+        self.encoded_storeMetadataRequest = bsp.demac_only(seqOf88)
+        self.storeMetadataRequest = rsp.asn1.decode('StoreMetadataRequest', self.encoded_storeMetadataRequest)
+
+        if secondSeqOf87 != None:
+            rsk_bin = bsp.demac_and_decrypt(secondSeqOf87)
+            rsk = rsp.asn1.decode('ReplaceSessionKeysRequest', rsk_bin)
+            # process replace_session_keys!
+            bsp = BspInstance(rsk['ppkEnc'], rsk['ppkCmac'], rsk['initialMacChainingValue'])
+            self.replaceSessionKeysRequest = rsk
+
+        self.upp = bsp.demac_and_decrypt(seqOf86)
+        return self.upp