Cloudflare has enabled ECH (staged) #393
Description
Seems like Cloudflare has gradually started to enable Encrypted ClientHello support. You can see it on rutracker.org and bo0om.ru for example.
ECH was instroduced on Cloudflare several years ago but has been disabled after very short test period. I could not find any announcement except for in CF documentation:
Caution
ECH is disabled globally, and cannot currently be enabled in the Cloudflare Dashboard.
Starting in August, 2024, ECH will be gradually released on free zones. It will not be possible to disable it. A toggle will be added to the Cloudflare Dashboard at a later point before ECH is made available for other zone plans.
Rutracker now opens in Firefox 130 in Russia without any circumvention methods. Apparently Firefox 130 does not require DNS-over-HTTPS for ECH to work.
Cloudflare uses a single ECH key & configuration for all the domains
$ dig +short rutracker.org HTTPS
1 . alpn="h3,h2" ipv4hint=104.21.32.39,172.67.182.196 ech=AEX+DQBBYQAgACB/ZNpruUIOMT7U9iv5DLgTo+oHQ7RI7GeHwd0tbccrCAAEAAEAAQASY2xvdWRmbGFyZS1lY2guY29tAAA= ipv6hint=2606:4700:3031::6815:2027,2606:4700:3034::a
c43:b6c4
$ dig +short crypto.cloudflare.com HTTPS
1 . alpn="http/1.1,h2" ipv4hint=162.159.137.85,162.159.138.85 ech=AEX+DQBBYQAgACB/ZNpruUIOMT7U9iv5DLgTo+oHQ7RI7GeHwd0tbccrCAAEAAEAAQASY2xvdWRmbGFyZS1lY2guY29tAAA= ipv6hint=2606:4700:7::a29f:8955,2606:4700:7:
:a29f:8a55
SvcParam: ech
SvcParamKey: ech (5)
SvcParamValue length: 71
ECHConfigList length: 69
ECHConfig: id=97 cloudflare-ech.com
Version: 0xfe0d
Length: 65
HKPE Key Config
Config Id: 97
KEM Id: DHKEM(X25519, HKDF-SHA256) (32)
Public Key length: 32
Public Key: 7f64da6bb9420e313ed4f62bf90cb813a3ea0743b448ec6787c1dd2d6dc72b08
Cipher Suites length: 4
Cipher Suites (1 suite)
Maximum Name Length: 0
Public Name length: 18
Public Name: cloudflare-ech.com
Extensions length: 0
cloudflare-ech.com is used as a canary domain (SNI) for TLS requests
Transport Layer Security
TLSv1.3 Record Layer: Handshake Protocol: Client Hello
Content Type: Handshake (22)
Version: TLS 1.0 (0x0301)
Length: 587
Handshake Protocol: Client Hello
Handshake Type: Client Hello (1)
Length: 583
Version: TLS 1.2 (0x0303)
Random: cb6244609a92947f8ccf9c7e731dc013cf00f739468bad266be3e9d4b40dfea4
Session ID Length: 32
Session ID: 2587cb2bc557eb6af6c561df526f2f42111108418712bfe550331cf0a4b1af53
Cipher Suites Length: 34
Cipher Suites (17 suites)
Compression Methods Length: 1
Compression Methods (1 method)
Extensions Length: 476
Extension: server_name (len=23) name=cloudflare-ech.com
Extension: extended_master_secret (len=0)
Extension: renegotiation_info (len=1)
Extension: supported_groups (len=14)
Extension: ec_point_formats (len=2)
Extension: application_layer_protocol_negotiation (len=14)
Extension: status_request (len=5)
Extension: delegated_credentials (len=10)
Extension: key_share (len=107) x25519, secp256r1
Extension: supported_versions (len=5) TLS 1.3, TLS 1.2
Extension: signature_algorithms (len=24)
Extension: record_size_limit (len=2)
Extension: encrypted_client_hello (len=217)
Type: encrypted_client_hello (65037)
Length: 217
Client Hello type: Outer Client Hello (0)
Cipher Suite: HKDF-SHA256/AES-128-GCM
KDF Id: HKDF-SHA256 (1)
AEAD Id: AES-128-GCM (1)
Config Id: 97
Enc length: 32
Enc: 08181d7e3ce624682fe03c8c31698f5a6c198aff850bccfedf6780e8dea6267e
Payload length: 175
Payload [truncated]: 20d54aebde0806f5ea62f287b713d9dba7e93636885160b2588633befe1e986046991c997bf9bd3e96927d99a3a3c0075870644ed6b9d0cd25e8da2ca197ee00907eef3955a5507b83bddecff3a720ad62ff577ac2b685ede87ae196c75e5f4c5ed02566350834bbc945b5f380
[JA4: t13d1713h2_5b57614c22b0_748f4c70de1c]
[JA4_r: t13d1713h2_002f,0035,009c,009d,1301,1302,1303,c009,c00a,c013,c014,c02b,c02c,c02f,c030,cca8,cca9_0005,000a,000b,000d,0017,001c,0022,002b,0033,fe0d,ff01_0403,0503,0603,0804,0805,0806,0401,0501,0601,0203,0201]
[JA3 Fullstring: 771,4865-4867-4866-49195-49199-52393-52392-49196-49200-49162-49161-49171-49172-156-157-47-53,0-23-65281-10-11-16-5-34-51-43-13-28-65037,29-23-24-25-256-257,0]
[JA3: ed3d2cb3d86125377f5a4d48e431af48]