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Add Encrypted Server Name Indication for TLS 1.3 #2097

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Add Encrypted Server Name Indication for TLS 1.3 #2097

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28 changes: 26 additions & 2 deletions scapy/layers/tls/extensions.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
SigAndHashAlgsField, _tls_hash_sig)
from scapy.layers.tls.session import _GenericTLSSessionInheritance
from scapy.layers.tls.crypto.groups import _tls_named_groups
from scapy.layers.tls.crypto.suites import _tls_cipher_suites
from scapy.themes import AnsiColorTheme
from scapy.compat import raw
from scapy.config import conf
Expand Down Expand Up @@ -61,7 +62,8 @@
0x33: "key_share",
0x3374: "next_protocol_negotiation",
# RFC-draft-agl-tls-nextprotoneg-03
0xff01: "renegotiation_info" # RFC 5746
0xff01: "renegotiation_info", # RFC 5746
0xffce: "encrypted_server_name"
}


Expand Down Expand Up @@ -182,6 +184,27 @@ class TLS_Ext_ServerName(TLS_Ext_PrettyPacketList): # RFC 4366
length_from=lambda pkt: pkt.servernameslen)]


class TLS_Ext_EncryptedServerName(TLS_Ext_PrettyPacketList):
name = "TLS Extension - Encrypted Server Name"
fields_desc = [ShortEnumField("type", 0xffce, _tls_ext),
ShortField("len", None),
EnumField("cipher", None, _tls_cipher_suites),
ShortEnumField("key_exchange_group", None,
_tls_named_groups),
FieldLenField("key_exchange_len", None,
length_of="key_exchange", fmt="H"),
XStrLenField("key_exchange", "",
length_from=lambda pkt: pkt.key_exchange_len),
FieldLenField("record_digest_len",
None, length_of="record_digest"),
XStrLenField("record_digest", "",
length_from=lambda pkt: pkt.record_digest_len),
FieldLenField("encrypted_sni_len", None,
length_of="encrypted_sni", fmt="H"),
XStrLenField("encrypted_sni", "",
length_from=lambda pkt: pkt.encrypted_sni_len)]


class TLS_Ext_MaxFragLen(TLS_Ext_Unknown): # RFC 4366
name = "TLS Extension - Max Fragment Length"
fields_desc = [ShortEnumField("type", 1, _tls_ext),
Expand Down Expand Up @@ -669,7 +692,8 @@ class TLS_Ext_RecordSizeLimit(TLS_Ext_Unknown): # RFC 8449
# 0x2f: TLS_Ext_CertificateAuthorities, #XXX
# 0x30: TLS_Ext_OIDFilters, #XXX
0x3374: TLS_Ext_NPN,
0xff01: TLS_Ext_RenegotiationInfo
0xff01: TLS_Ext_RenegotiationInfo,
0xffce: TLS_Ext_EncryptedServerName
}


Expand Down
48 changes: 48 additions & 0 deletions test/tls13.uts
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Original file line number Diff line number Diff line change
Expand Up @@ -619,6 +619,54 @@ m = t.inner.msg[0]
assert(isinstance(m, TLSApplicationData))
assert(m.data == payload)

= TLS_Ext_EncryptedServerName(), dissect
~ crypto_advanced

clientHello3 = clean("""
16030102c4010002c003034b1 40e7d15fc8db422cec056fbaf 0285d306df4eedad1bc6ea57d 5114e6bd52a20a5b9c7445955 e296b886469c974648cda0a68
5d3c06d884e388f6475c32e03 2d0024130113031302c02bc02 fcca9cca8c02cc030c00ac009 c013c01400330039002f00350 00a0100025300170000ff0100
0100000a000e000c001d00170 018001901000101000b000201 00002300000010000b0009086 87474702f312e310005000501 000000000033006b0069001d0
02037adee0aacc37b08d47222 caf6a5097a800fcf8406ae118 38f6348294d2dde1200170041 048b127c905d6d487a40b8b19 c99c56aa1a8c208218c178dae
02568547b2ce8f538a530b858 a7a2f608d66e148baa5693d03 c519b45017c63f48c5a4c1238 707bc002b0009080304030303 020301000d001800160403050
3060308040805080604010501 060102030201002d00020101f fce016e1301001d0020912e86 b776ee552a6bb1e2c70d7b467 770b190432237cc743a93091d
ce24623500208bc16fdcbbc7c 8756808c94f70464d68297975 f33be90e1a200633f5eb2d4c6 101249e073bff833782e57e88 2519a53ef8bde4c94a7878a2f
8461aec57802440007c7b2dab 986d9bc79257ce00ca6a998b1 fadb0114161069d364ccebae8 dab6c88151f297daeaecfd2e1 a598a486e2efc9561298f8dd5
f35d184f0e87768777d253e68 952b730a24b342fde10df4f8e 82afdc2f10c2481634d92015d 9d5e6a9566494735d9c079115 bdeb0cd019098d1cf847c53ef
4aac41560cacdc7ce166399df 5b0c0af91d5be3f7d8224755a aa6046de52875f9ef9ac15372 7ce08019bc2648beb4b1418cb 4979ff7eaeedaec2b15695508
4d5a480cb939fdc7f00e6cc6f c0f9675276a9d607686c4d779 d4bb7544fb60c7f3079afbc74 61ed67fd55a78c44d6f8d4eaf 386acc17dea11e37a09f63da3
d059243b35f449e891255ac7b 4f631509d7060f001c0002400 1
""")
t = TLS(clientHello3)
clientESNI = t.msg[0].ext[11]
assert isinstance(clientESNI, TLS_Ext_EncryptedServerName) and clientESNI.cipher == 4865


= TLS_Ext_EncryptedServerName(), basic instantiation
~ crypto_advanced

esni = TLS_Ext_EncryptedServerName(key_exchange_group=29,encrypted_sni=clean("""
ffce016e1301001d00209 12e86b776ee552a6bb1e2 c70d7b467770b19043223 7cc743a93091dce246235
00208bc16fdcbbc7c8756 808c94f70464d68297975 f33be90e1a200633f5eb2 d4c6101249e073bff8337
82e57e882519a53ef8bde 4c94a7878a2f8461aec57 802440007c7b2dab986d9 bc79257ce00ca6a998b1f
adb0114161069d364cceb ae8dab6c88151f297daea ecfd2e1a598a486e2efc9 561298f8dd5f35d184f0e
87768777d253e68952b73 0a24b342fde10df4f8e82 afdc2f10c2481634d9201 5d9d5e6a9566494735d9c
079115bdeb0cd019098d1 cf847c53ef4aac41560ca cdc7ce166399df5b0c0af 91d5be3f7d8224755aaa6
046de52875f9ef9ac1537 27ce08019bc2648beb4b1 418cb4979ff7eaeedaec2 b156955084d5a480cb939
fdc7f00e6cc6fc0f96752 76a9d607686c4d779d4bb 7544fb60c7f3079afbc74 61ed67fd55a78c44d6f8d
4eaf386acc17dea11e37a 09f63da3d059243b35f44 9e891255ac7b4f631509d 7060f
"""))
assert esni.key_exchange_group == 29 and esni.encrypted_sni==clean("""
ffce016e1301001d00209 12e86b776ee552a6bb1e2 c70d7b467770b19043223 7cc743a93091dce246235
00208bc16fdcbbc7c8756 808c94f70464d68297975 f33be90e1a200633f5eb2 d4c6101249e073bff8337
82e57e882519a53ef8bde 4c94a7878a2f8461aec57 802440007c7b2dab986d9 bc79257ce00ca6a998b1f
adb0114161069d364cceb ae8dab6c88151f297daea ecfd2e1a598a486e2efc9 561298f8dd5f35d184f0e
87768777d253e68952b73 0a24b342fde10df4f8e82 afdc2f10c2481634d9201 5d9d5e6a9566494735d9c
079115bdeb0cd019098d1 cf847c53ef4aac41560ca cdc7ce166399df5b0c0af 91d5be3f7d8224755aaa6
046de52875f9ef9ac1537 27ce08019bc2648beb4b1 418cb4979ff7eaeedaec2 b156955084d5a480cb939
fdc7f00e6cc6fc0f96752 76a9d607686c4d779d4bb 7544fb60c7f3079afbc74 61ed67fd55a78c44d6f8d
4eaf386acc17dea11e37a 09f63da3d059243b35f44 9e891255ac7b4f631509d 7060f
""")

= Decrypt a TLS 1.3 session - Decrypt and parse server Application Data
~ crypto_advanced
# Values from RFC8448, section 3
Expand Down