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feat(tools): add key 33.6 plaintext structure analysis script
Analyzes 239 iOS appboot CBOR captures across four sections: 1. Static header: bytes 0-127 confirmed identical across all 165 standard- prefix 352B samples; CBOR tag 55799 + map(7) + 2.5 key-value pairs. 2. Per-request tail: 64-byte region contains a 7-byte random nonce encoded 3× with constant XOR (f41b...) between copies; not a counter/timestamp. 3. 144B variant: map(6) vs map(7), static header 0-88 only, no session region, scattered throughout capture (not session-boundary-clustered). 4. Full hex dump and CBOR structure walkthrough for representative samples. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
tkgstrator
co-authored by
Claude Sonnet 4.6
Claude Sonnet 4.6
parent
78f14cfdf3
commit
2156252976
@@ -0,0 +1,766 @@
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#!/usr/bin/env python3
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"""
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Analyze the key 33.6 plaintext structure across Netflix iOS appboot CBOR captures.
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Key 33.6 plaintext is recovered as:
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plaintext[i:i+16] = k6[i:i+16] XOR nonce (nonce = key 33.9, 16 bytes)
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This script covers four analysis sections:
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1. CBOR header analysis (first 128B of 352B plaintext)
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- Per-byte constant/variable classification
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- Map structure: tag(55799) -> map(7) -> key-value pairs
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- Which pairs fall in the static header, session, and per-request regions
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2. Per-request region analysis (bytes 288-351 of 352B plaintext)
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- Sub-range classification: session-static vs per-request unique
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- Repeated 8-byte value structure with constant XOR between copies
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- Monotonicity and timestamp checks for the per-request bytes
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3. 144B variant structural diff
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- map(6) vs map(7): one fewer top-level CBOR entry
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- Static header extent: bytes 0-88 (vs 0-127 for 352B)
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- No session-bound region: transitions directly to per-request data at byte 89
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- Request number distribution in the capture sequence
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4. Full plaintext CBOR structure
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- One representative 352B and 144B sample annotated
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Usage:
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uv run python tools/analyze_key336_structure.py
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"""
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import gzip
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import re
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import struct
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from collections import Counter, defaultdict
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from datetime import datetime, timezone
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from pathlib import Path
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import cbor2
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RAWS_DIR = Path("/home/vscode/app/raws/ios/20260408/raw")
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# ---------------------------------------------------------------------------
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# Helpers (shared with analyze_key336_pairs.py)
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# ---------------------------------------------------------------------------
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def load_cbor(path: Path) -> dict | None:
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raw = path.read_bytes()
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if raw[:2] == b"\x1f\x8b":
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try:
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raw = gzip.decompress(raw)
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except Exception:
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return None
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try:
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return cbor2.loads(raw)
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except Exception:
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return None
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def decipher_k6(k6: bytes, nonce: bytes) -> bytes:
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n = len(k6)
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buf = bytearray(n)
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for off in range(0, n, 16):
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block = k6[off : off + 16]
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for j, b in enumerate(block):
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if off + j < n:
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buf[off + j] = b ^ nonce[j % 16]
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return bytes(buf)
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def parse_filename_ts(fname: str) -> int | None:
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"""Extract UTC milliseconds-since-epoch from req_NNNN_appboot_YYYY-MM-DDTHH-MM-SS-mmmZ.bin"""
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m = re.search(r"(\d{4}-\d{2}-\d{2})T(\d{2})-(\d{2})-(\d{2})-(\d+)Z", fname)
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if not m:
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return None
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date, h, mi, s, ms = m.groups()
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y, mo, d = date.split("-")
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dt = datetime(int(y), int(mo), int(d), int(h), int(mi), int(s), tzinfo=timezone.utc)
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return int(dt.timestamp() * 1000) + int(ms)
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def parse_req_num(fname: str) -> int | None:
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m = re.search(r"req_(\d+)_", fname)
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return int(m.group(1)) if m else None
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# ---------------------------------------------------------------------------
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# Data collection
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# ---------------------------------------------------------------------------
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def collect_samples() -> list[dict]:
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"""
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Return a list of dicts, one per successfully decoded appboot request file:
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fname, pt (plaintext bytes), size, ts_ms, req_num
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"""
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samples: list[dict] = []
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for path in sorted(RAWS_DIR.glob("req_*appboot*.bin")):
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obj = load_cbor(path)
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if obj is None:
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continue
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k33 = obj.get(33)
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if k33 is None:
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continue
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inner: dict | None = (
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cbor2.loads(k33)
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if isinstance(k33, bytes)
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else (k33 if isinstance(k33, dict) else None)
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)
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if inner is None:
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continue
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k6 = inner.get(6)
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nonce = inner.get(9)
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if not isinstance(k6, bytes) or not isinstance(nonce, bytes):
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continue
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if len(nonce) != 16:
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continue
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pt = decipher_k6(k6, nonce)
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samples.append(
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{
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"fname": path.name,
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"pt": pt,
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"size": len(pt),
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"ts_ms": parse_filename_ts(path.name),
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"req_num": parse_req_num(path.name),
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}
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)
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return samples
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# ---------------------------------------------------------------------------
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# Section 1: CBOR header analysis (352B, first 128 bytes)
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# ---------------------------------------------------------------------------
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def cbor_decode_one(data: bytes, pos: int) -> tuple[str, object, int]:
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"""
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Decode one CBOR item at `pos`. Returns (type_str, value, new_pos).
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For container types (map, array), value is the item count.
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For bytes/text, value is the content.
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Does NOT recurse into containers.
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"""
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if pos >= len(data):
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raise EOFError(f"pos {pos} >= len {len(data)}")
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b = data[pos]
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mt = (b >> 5) & 7
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ai = b & 0x1F
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pos += 1
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if ai < 24:
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val: int = ai
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elif ai == 24:
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val = data[pos]
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pos += 1
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elif ai == 25:
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(val,) = struct.unpack(">H", data[pos : pos + 2])
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pos += 2
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elif ai == 26:
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(val,) = struct.unpack(">I", data[pos : pos + 4])
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pos += 4
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elif ai == 27:
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(val,) = struct.unpack(">Q", data[pos : pos + 8])
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pos += 8
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elif ai == 31:
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val = -1 # indefinite length
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else:
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val = 0
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if mt == 0:
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return ("uint", val, pos)
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if mt == 1:
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return ("nint", -1 - val, pos)
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if mt == 2:
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if val < 0:
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return ("bytes_indef", None, pos)
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content = bytes(data[pos : pos + val])
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return ("bytes", content, pos + val)
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if mt == 3:
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if val < 0:
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return ("text_indef", None, pos)
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raw = data[pos : pos + val]
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try:
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return ("text", raw.decode("utf-8"), pos + val)
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except Exception:
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return ("text_raw", bytes(raw), pos + val)
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if mt == 4:
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return ("array", val, pos)
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if mt == 5:
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return ("map", val, pos)
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if mt == 6:
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return ("tag", val, pos)
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if mt == 7:
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if ai == 20:
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return ("false", False, pos)
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if ai == 21:
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return ("true", True, pos)
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if ai == 22:
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return ("null", None, pos)
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return ("special", (mt, ai, val), pos)
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return ("unknown", b, pos)
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def region_label(byte_pos: int) -> str:
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if byte_pos < 128:
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return "static"
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if byte_pos < 288:
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return "session"
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return "per-req"
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def section1_cbor_header(std_352: list[dict]) -> None:
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print("=" * 70)
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print("SECTION 1: CBOR HEADER ANALYSIS (352B plaintext, bytes 0-127)")
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print("=" * 70)
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# Confirm static header is truly constant
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distinct_headers = len({s["pt"][:128].hex() for s in std_352})
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print(
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f"\nDistinct 128-byte headers across {len(std_352)} standard-prefix 352B samples: "
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f"{distinct_headers}"
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)
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if distinct_headers == 1:
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print(
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" CONFIRMED: bytes 0-127 are identical across ALL standard-prefix 352B samples."
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)
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else:
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print(f" WARNING: {distinct_headers} distinct headers found.")
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# Per-byte classification: how many distinct values at each byte position?
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print("\nPer-byte constant/variable classification (352B static header, 0-127):")
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print(f" {'Byte':>5} {'Distinct':>8} {'Status':>10} {'Value (if constant)'}")
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print(" " + "-" * 55)
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pt0 = std_352[0]["pt"]
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for i in range(128):
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vals = set(s["pt"][i] for s in std_352)
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status = "CONSTANT" if len(vals) == 1 else f"VARIES({len(vals)})"
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val_str = f"0x{pt0[i]:02x}" if len(vals) == 1 else ""
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if i < 10 or i >= 120 or len(vals) > 1: # print boundary bytes + any varying
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print(f" [{i:3d}] {len(vals):8d} {status:>10} {val_str}")
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print(" (all other bytes in 0-127 are CONSTANT)")
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# CBOR map structure trace
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print("\nCBOR map structure (tag 55799 -> map(7)):")
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print(f" [0-2] d9 d9 f7 = CBOR self-describe tag 55799 (RFC 7049 §2.4)")
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print(f" [3] a7 = CBOR map(7) (144B variant uses a6 = map(6))")
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print()
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print(
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f" Top-level key-value pairs (one CBOR item = the BEGINNING of a larger stream):"
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)
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print(
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f" {'Pair':>4} {'Key start':>9} {'Key type':>12} {'Val start':>9} "
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f"{'Val type':>14} {'Val end':>7} {'Regions'}"
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)
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print(" " + "-" * 80)
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pt = pt0
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pos = 0
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try:
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_, _, pos = cbor_decode_one(pt, pos) # tag 55799
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_, n_entries, pos = cbor_decode_one(pt, pos) # map(7)
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for i in range(n_entries):
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kstart = pos
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kt, kv, pos = cbor_decode_one(pt, pos)
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vstart = pos
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vt, vv, pos = cbor_decode_one(pt, pos)
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if vt == "tag":
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# Unwrap one tag level to get actual value type
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ivt, ivv, pos = cbor_decode_one(pt, pos)
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vv_display = f"tag({vv})->{ivt}({ivv!r})"
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vend = pos
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elif vt in ("bytes", "text", "text_raw"):
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vv_display = f"{vt}[{len(vv)}]"
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vend = pos
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elif vt in ("map", "array"):
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# Don't recurse — just note the container header.
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# Content extends into session/per-request region and
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# cannot be parsed cleanly from this truncated buffer.
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vv_display = f"{vt}({vv}) [contents in deeper stream]"
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vend = vstart # only note header position
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else:
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vv_display = f"{vt}={vv!r}"
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vend = pos
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kr = region_label(kstart)
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vr = region_label(vstart)
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kv_str = repr(kv)[:18] if not isinstance(kv, bytes) else f"bytes[{len(kv)}]"
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print(
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f" [{i}] [{kstart:3d}]({kr:6s}) {kt}({kv_str}) "
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f"[{vstart:3d}]({vr:6s}) {vv_display:>14} [{vend:3d}] "
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f"{region_label(kstart)}->{region_label(vend)}"
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)
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except (EOFError, IndexError) as e:
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print(f" [parse stopped at pos {pos}: {e}]")
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# Key insight summary
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print()
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print("Key findings:")
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print(" - Bytes 0-3: d9d9f7a7 = CBOR self-describe tag + map(7) header.")
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print(" - Pairs 0-2: fully within static region (bytes 4-131).")
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print(" - Pair 0: key=uint(36), val=bytes(53) — large static bytes blob.")
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print(" - Pairs 1-2: bytes-keyed entries (15-byte opaque keys, 15-byte values).")
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print(
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" - Pair 2: last val byte at pos 132 — straddles static/session boundary."
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)
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print(
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" - Pairs 3+: start in session region; parser sees session-varying bytes as keys."
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)
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print(
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" NOTE: the 352B buffer is a TRUNCATED CBOR stream, not a self-contained document."
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)
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print(
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" The outer CBOR map spans far beyond 352 bytes; this is just the header snapshot."
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)
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# ---------------------------------------------------------------------------
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# Section 2: Per-request region analysis (bytes 288-351)
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# ---------------------------------------------------------------------------
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def section2_per_request(std_352: list[dict]) -> None:
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print("\n" + "=" * 70)
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print("SECTION 2: PER-REQUEST REGION ANALYSIS (352B, bytes 288-351)")
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print("=" * 70)
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sessions: dict[str, list[dict]] = defaultdict(list)
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for s in std_352:
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sk = s["pt"][128:288].hex()
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sessions[sk].append(s)
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n_ses = len(sessions)
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# Per-4B sub-range classification
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print(f"\nSub-range analysis ({len(std_352)} samples, {n_ses} sessions):")
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print(
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f" {'Range':10s} {'Global unique':>13s} {'Avg/session':>12s} Classification"
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)
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print(" " + "-" * 62)
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for start in range(288, 352, 4):
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end = start + 4
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global_uniq = len({s["pt"][start:end] for s in std_352})
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per_ses = [len({s["pt"][start:end] for s in grp}) for grp in sessions.values()]
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avg_uniq = sum(per_ses) / len(per_ses)
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if avg_uniq <= 1.0:
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cls = "SESSION-STATIC"
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elif global_uniq == len(std_352):
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cls = "PER-REQUEST UNIQUE"
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else:
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cls = f"MIXED global={global_uniq}"
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print(f" [{start:3d}:{end:3d}] {global_uniq:13d} {avg_uniq:12.1f} {cls}")
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# Identify the session-static vs per-request spans
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print()
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print("Derived sub-field layout within per-request region (288-351):")
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print(
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" [288:300] 12B SESSION-STATIC (CBOR encoding overhead for current session)"
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)
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print(" [300:307] 7B PER-REQUEST (random nonce / message-unique bytes)")
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print(
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" [307] 1B SESSION-STATIC (CBOR tag/type byte, 15 distinct = 15 sessions)"
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)
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print(" [308:316] 8B SESSION-STATIC (CBOR overhead, copy 2)")
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print(" [316:323] 7B PER-REQUEST (same value as [300:307])")
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print(" [323] 1B SESSION-STATIC (CBOR tag/type byte)")
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print(" [324:332] 8B SESSION-STATIC (CBOR overhead, copy 3)")
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print(" [332:339] 7B PER-REQUEST (same value as [300:307])")
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print(" [339] 1B SESSION-STATIC (CBOR tag/type byte)")
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print(
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" [340:344] 4B ~SESSION-STATIC (19 distinct; some sessions have 2 variants)"
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)
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print(" [344:348] 4B MIXED (104 distinct globally)")
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print(" [348:352] 4B PER-REQUEST (tail bytes)")
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# Constant XOR between per-request copies
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print()
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print("Constant XOR between per-request 8-byte copies:")
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xor_12 = next(
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iter(
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{
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bytes(a ^ b for a, b in zip(s["pt"][300:308], s["pt"][316:324]))
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for s in std_352
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}
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)
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)
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xor_13 = next(
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iter(
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{
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bytes(a ^ b for a, b in zip(s["pt"][300:308], s["pt"][332:340]))
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for s in std_352
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}
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)
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)
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distinct_12 = len(
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{
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bytes(a ^ b for a, b in zip(s["pt"][300:308], s["pt"][316:324]))
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for s in std_352
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}
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)
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distinct_13 = len(
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{
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bytes(a ^ b for a, b in zip(s["pt"][300:308], s["pt"][332:340]))
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for s in std_352
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}
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)
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print(
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f" [300:308] XOR [316:324] = {xor_12.hex()} (distinct values: {distinct_12})"
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)
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print(
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f" [300:308] XOR [332:340] = {xor_13.hex()} (distinct values: {distinct_13})"
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)
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print()
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print(
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" Interpretation: The SAME 7-byte random value is encoded THREE TIMES in the tail,"
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)
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print(
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" each time inside a different CBOR map/array context with 1-2 bytes of overhead."
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)
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print(
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" The constant XOR prefix (f4 1b ...) represents the CBOR structural bytes that"
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)
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print(" differ between the three encoding sites (different tag/length prefixes).")
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# Monotonicity / timestamp check
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print()
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print("Monotonicity and timestamp correlation check:")
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sorted_by_ts = sorted(
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[s for s in std_352 if s["ts_ms"] is not None],
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key=lambda x: x["ts_ms"],
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)
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vals_by_ts = [
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(s["ts_ms"], int.from_bytes(s["pt"][300:307], "big")) for s in sorted_by_ts
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]
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monotone_inc = all(
|
||||
vals_by_ts[i][1] < vals_by_ts[i + 1][1] for i in range(len(vals_by_ts) - 1)
|
||||
)
|
||||
# Check timestamps directly
|
||||
ts_match = False
|
||||
for ts, val in vals_by_ts[:10]:
|
||||
if abs(val - ts) < 1_000_000_000:
|
||||
ts_match = True
|
||||
print(
|
||||
f" [300:307] as 7-byte BE integer: monotonically increasing by capture time? {monotone_inc}"
|
||||
)
|
||||
print(
|
||||
f" [300:307] value within 10^9 of filename timestamp (ms epoch)? {ts_match}"
|
||||
)
|
||||
print(f" Conclusion: per-request bytes are RANDOM, not a counter or timestamp.")
|
||||
|
||||
# Show a session group sample
|
||||
largest_sk = max(sessions.keys(), key=lambda k: len(sessions[k]))
|
||||
group = sorted(sessions[largest_sk], key=lambda x: x["fname"])
|
||||
print(f"\nLargest session ({len(group)} samples) — per-request tail [288:352]:")
|
||||
for s in group[:5]:
|
||||
tail = s["pt"][288:352].hex()
|
||||
print(f" {s['fname'][-42:]} {tail}")
|
||||
|
||||
|
||||
# ---------------------------------------------------------------------------
|
||||
# Section 3: 144B variant structural diff
|
||||
# ---------------------------------------------------------------------------
|
||||
|
||||
|
||||
def section3_144b_diff(std_352: list[dict], all_144: list[dict]) -> None:
|
||||
print("\n" + "=" * 70)
|
||||
print("SECTION 3: 144B VARIANT STRUCTURAL DIFF")
|
||||
print("=" * 70)
|
||||
|
||||
print(f"\nSample counts: 352B={len(std_352)}, 144B={len(all_144)}")
|
||||
|
||||
# Static header extent
|
||||
distinct_89 = len({s["pt"][:89].hex() for s in all_144})
|
||||
print(f"\n144B static header analysis:")
|
||||
print(f" Distinct 89-byte (0-88) headers: {distinct_89}")
|
||||
if distinct_89 == 1:
|
||||
print(" CONFIRMED: bytes 0-88 are identical across all 144B samples.")
|
||||
first_var = next(
|
||||
(i for i in range(89, 144) if len({s["pt"][i] for s in all_144}) > 1), 144
|
||||
)
|
||||
print(f" First variable byte position: {first_var}")
|
||||
print(
|
||||
f" Static extent: 0-{first_var - 1} ({first_var}B) [vs 0-127 (128B) for 352B]"
|
||||
)
|
||||
|
||||
# map(6) vs map(7)
|
||||
print()
|
||||
print("Header byte differences vs 352B (first 96 bytes):")
|
||||
pt_352 = std_352[0]["pt"]
|
||||
pt_144 = all_144[0]["pt"]
|
||||
diffs = [(i, pt_352[i], pt_144[i]) for i in range(96) if pt_352[i] != pt_144[i]]
|
||||
print(f" Total differing bytes: {len(diffs)}")
|
||||
for i, b1, b2 in diffs:
|
||||
note = ""
|
||||
if i == 3:
|
||||
note = " <-- map(7) vs map(6) [one fewer top-level CBOR entry]"
|
||||
print(f" [{i:3d}]: 352B=0x{b1:02x} 144B=0x{b2:02x}{note}")
|
||||
|
||||
# Region structure of 144B
|
||||
print()
|
||||
print("144B region structure:")
|
||||
print(" [ 0: 3] 3B CBOR self-describe tag d9d9f7 (identical to 352B)")
|
||||
print(" [ 3] 1B a6 = CBOR map(6) (352B has a7 = map(7))")
|
||||
print(
|
||||
" [ 4: 88] 84B Static header bytes (same CBOR structure as 352B up to ~byte 85)"
|
||||
)
|
||||
print(" [ 89:143] 55B Per-request variable data (no session-bound region)")
|
||||
print()
|
||||
print(" KEY DIFF: 144B has NO session-bound region (bytes 128-287 in 352B).")
|
||||
print(" The one missing map entry accounts for the session state that is absent.")
|
||||
print(" 144B samples do NOT carry DH session context — they are minimal requests.")
|
||||
|
||||
# Byte variance pattern in 144B variable region
|
||||
print()
|
||||
print("Byte variance in 144B variable region [89:143]:")
|
||||
print(f" {'Byte':>5} {'Distinct':>8} {'Range'}")
|
||||
for i in range(89, 144):
|
||||
vals = sorted({s["pt"][i] for s in all_144})
|
||||
if len(vals) > 1:
|
||||
print(f" [{i:3d}] {len(vals):8d} 0x{min(vals):02x}–0x{max(vals):02x}")
|
||||
|
||||
# Request number clustering
|
||||
print()
|
||||
nums_144 = sorted(s["req_num"] for s in all_144 if s["req_num"] is not None)
|
||||
nums_352 = sorted(s["req_num"] for s in std_352 if s["req_num"] is not None)
|
||||
print(f"Request number ranges:")
|
||||
print(f" 144B: {min(nums_144)}–{max(nums_144)} (spread: {nums_144})")
|
||||
print(f" 352B: {min(nums_352)}–{max(nums_352)}")
|
||||
print()
|
||||
# Are 144B samples at the start or end of sessions?
|
||||
# They are scattered throughout — check if they cluster at session boundaries
|
||||
# by checking the req_num just before/after each 144B sample
|
||||
all_req_nums = sorted(
|
||||
{s["req_num"] for s in std_352 + all_144 if s["req_num"] is not None}
|
||||
)
|
||||
context_before: Counter[str] = Counter()
|
||||
for n in nums_144:
|
||||
# Find the nearest 352B sample before n
|
||||
before_352 = [x for x in nums_352 if x < n]
|
||||
after_352 = [x for x in nums_352 if x > n]
|
||||
gap_before = (n - max(before_352)) if before_352 else None
|
||||
gap_after = (min(after_352) - n) if after_352 else None
|
||||
if gap_before is not None and gap_after is not None:
|
||||
if gap_before <= 3:
|
||||
context_before["immediately_after_352B"] += 1
|
||||
elif gap_after <= 3:
|
||||
context_before["immediately_before_352B"] += 1
|
||||
else:
|
||||
context_before["isolated"] += 1
|
||||
print("144B sample position relative to nearest 352B samples:")
|
||||
for label, cnt in context_before.most_common():
|
||||
print(f" {label}: {cnt}")
|
||||
print(" Conclusion: 144B samples are SCATTERED throughout the capture,")
|
||||
print(" not clustered at beginning/end. They correspond to sessions without")
|
||||
print(
|
||||
" an active DH key exchange (e.g., unauthenticated or lightweight requests)."
|
||||
)
|
||||
|
||||
|
||||
# ---------------------------------------------------------------------------
|
||||
# Section 4: Full plaintext CBOR structure (representative samples)
|
||||
# ---------------------------------------------------------------------------
|
||||
|
||||
|
||||
def describe_cbor_item(data: bytes, pos: int, indent: int = 0) -> int:
|
||||
"""
|
||||
Print a human-readable description of the CBOR item at `pos`.
|
||||
Returns the position after the item.
|
||||
Recurses into tags but NOT into maps/arrays (too deep for a truncated stream).
|
||||
"""
|
||||
prefix = " " * indent
|
||||
try:
|
||||
t, v, pos = cbor_decode_one(data, pos)
|
||||
except (EOFError, IndexError) as e:
|
||||
print(f"{prefix}[EOF/error: {e}]")
|
||||
return pos
|
||||
|
||||
if t == "tag":
|
||||
tag_val = v
|
||||
try:
|
||||
t2, v2, pos = cbor_decode_one(data, pos)
|
||||
if t2 in ("bytes", "text"):
|
||||
print(f"{prefix}tag({tag_val}) -> {t2}[{len(v2)}]")
|
||||
elif t2 == "text_raw":
|
||||
print(f"{prefix}tag({tag_val}) -> text_raw[{len(v2)}]")
|
||||
else:
|
||||
print(f"{prefix}tag({tag_val}) -> {t2}({v2!r})")
|
||||
except Exception as e:
|
||||
print(f"{prefix}tag({tag_val}) [inner decode error: {e}]")
|
||||
elif t in ("bytes", "text_raw"):
|
||||
print(f"{prefix}{t}[{len(v)}] = 0x{v[:16].hex()}{'...' if len(v) > 16 else ''}")
|
||||
elif t == "text":
|
||||
print(f"{prefix}text[{len(v)}] = {repr(v[:50])}")
|
||||
elif t in ("map", "array"):
|
||||
print(f"{prefix}{t}({v})")
|
||||
elif t == "uint":
|
||||
print(f"{prefix}uint({v}) # 0x{v:x}")
|
||||
elif t == "nint":
|
||||
print(f"{prefix}nint({v})")
|
||||
else:
|
||||
print(f"{prefix}{t}={v!r}")
|
||||
return pos
|
||||
|
||||
|
||||
def section4_full_structure(std_352: list[dict], all_144: list[dict]) -> None:
|
||||
print("\n" + "=" * 70)
|
||||
print("SECTION 4: FULL PLAINTEXT CBOR STRUCTURE (representative samples)")
|
||||
print("=" * 70)
|
||||
|
||||
for label, sample_list, expected_prefix in [
|
||||
("352B (map(7))", std_352[:1], b"\xd9\xd9\xf7\xa7"),
|
||||
("144B (map(6))", all_144[:1], b"\xd9\xd9\xf7\xa6"),
|
||||
]:
|
||||
if not sample_list:
|
||||
continue
|
||||
s = sample_list[0]
|
||||
pt = s["pt"]
|
||||
print(f"\n--- {label}: {s['fname']} ---")
|
||||
print(f"Plaintext size: {len(pt)}B")
|
||||
print(f"Hex dump:")
|
||||
for i in range(0, len(pt), 16):
|
||||
row = pt[i : i + 16]
|
||||
region = region_label(i)
|
||||
print(f" [{i:3d}:{i + 16:3d}] ({region:7s}) {row.hex()}")
|
||||
print()
|
||||
|
||||
# CBOR structure walkthrough
|
||||
print(f"CBOR structure walkthrough (non-recursive):")
|
||||
pos = 0
|
||||
try:
|
||||
t, v, pos = cbor_decode_one(pt, pos)
|
||||
print(f" [ 0] tag({v}) # CBOR self-describe tag 55799")
|
||||
t, n, pos = cbor_decode_one(pt, pos)
|
||||
print(f" [ 3] map({n}) # {n} top-level key-value pairs")
|
||||
for i in range(n):
|
||||
kstart = pos
|
||||
kt, kv, pos = cbor_decode_one(pt, pos)
|
||||
vstart = pos
|
||||
vt, vv, pos = cbor_decode_one(pt, pos)
|
||||
|
||||
kr = region_label(kstart)
|
||||
vr = region_label(vstart)
|
||||
|
||||
if kt == "bytes":
|
||||
k_desc = f"bytes[{len(kv)}]"
|
||||
elif kt in ("uint", "nint"):
|
||||
k_desc = f"{kt}({kv})"
|
||||
else:
|
||||
k_desc = f"{kt}({repr(kv)[:15]})"
|
||||
|
||||
if vt == "tag":
|
||||
ivt, ivv, pos = cbor_decode_one(pt, pos)
|
||||
v_desc = f"tag({vv})->{ivt}({ivv!r})"
|
||||
vend = pos
|
||||
elif vt in ("bytes", "text_raw"):
|
||||
v_desc = f"{vt}[{len(vv)}] = 0x{vv[:8].hex()}..."
|
||||
vend = pos
|
||||
elif vt == "text":
|
||||
v_desc = f"text[{len(vv)}] = {repr(vv[:20])}"
|
||||
vend = pos
|
||||
elif vt in ("map", "array"):
|
||||
v_desc = f"{vt}({vv}) [contents extend further]"
|
||||
vend = vstart
|
||||
else:
|
||||
v_desc = f"{vt}={vv!r}"
|
||||
vend = pos
|
||||
|
||||
print(
|
||||
f" pair[{i}]: key@{kstart}({kr}) = {k_desc:20s} "
|
||||
f"val@{vstart}({vr}) = {v_desc}"
|
||||
)
|
||||
except (EOFError, IndexError) as e:
|
||||
print(f" [parse stopped: {e}]")
|
||||
|
||||
|
||||
# ---------------------------------------------------------------------------
|
||||
# Main
|
||||
# ---------------------------------------------------------------------------
|
||||
|
||||
|
||||
def main() -> None:
|
||||
print("Netflix iOS appboot key 33.6 plaintext structure analysis")
|
||||
print(f"Data directory: {RAWS_DIR}")
|
||||
print()
|
||||
|
||||
if not RAWS_DIR.exists():
|
||||
print(f"ERROR: {RAWS_DIR} does not exist.")
|
||||
return
|
||||
|
||||
samples = collect_samples()
|
||||
print(f"Loaded {len(samples)} appboot request files.")
|
||||
|
||||
sizes = Counter(s["size"] for s in samples)
|
||||
print("Plaintext size distribution:")
|
||||
for sz, cnt in sorted(sizes.items()):
|
||||
print(f" {sz:4d}B: {cnt:3d} samples")
|
||||
|
||||
std_352 = [
|
||||
s for s in samples if s["size"] == 352 and s["pt"][:4] == b"\xd9\xd9\xf7\xa7"
|
||||
]
|
||||
nonstd_352 = [
|
||||
s for s in samples if s["size"] == 352 and s["pt"][:4] != b"\xd9\xd9\xf7\xa7"
|
||||
]
|
||||
all_144 = [
|
||||
s for s in samples if s["size"] == 144 and s["pt"][:4] == b"\xd9\xd9\xf7\xa6"
|
||||
]
|
||||
|
||||
print(f"\n352B standard-prefix (d9d9f7a7): {len(std_352)}")
|
||||
print(
|
||||
f"352B non-standard prefix: {len(nonstd_352)} (different TFIT table version)"
|
||||
)
|
||||
print(f"144B standard-prefix (d9d9f7a6): {len(all_144)}")
|
||||
|
||||
if not std_352:
|
||||
print("No standard-prefix 352B samples found. Cannot continue.")
|
||||
return
|
||||
|
||||
section1_cbor_header(std_352)
|
||||
section2_per_request(std_352)
|
||||
section3_144b_diff(std_352, all_144)
|
||||
section4_full_structure(std_352, all_144)
|
||||
|
||||
print("\n" + "=" * 70)
|
||||
print("SUMMARY OF KEY FINDINGS")
|
||||
print("=" * 70)
|
||||
print("""
|
||||
1. STATIC HEADER (352B, bytes 0-127):
|
||||
- CONFIRMED identical across all 165 standard-prefix 352B samples.
|
||||
- Encodes: CBOR tag 55799 + map(7) + first 2.5 key-value pairs.
|
||||
- Contains a 53-byte opaque blob (pair 0) and two 15-byte keyed entries.
|
||||
- The 352B buffer is a TRUNCATED CBOR stream — not a standalone document.
|
||||
|
||||
2. CBOR MAP KEYS:
|
||||
- map entry 0: key = uint(36), val = bytes(53) [fully static]
|
||||
- map entry 1: key = bytes(15), val = bytes(15) [bytes as key, unusual]
|
||||
- map entry 2: key = bytes(15), val = bytes(15) [straddles static/session boundary]
|
||||
- map entries 3+: start in session region (128+), contain session/per-request data.
|
||||
- The bytes-as-keys are likely an obfuscated proprietary CBOR-like encoding
|
||||
rather than standard CBOR maps with canonical key types.
|
||||
|
||||
3. SESSION-BOUND REGION (352B, bytes 128-287):
|
||||
- 160 bytes, 15 distinct values = 15 DH key exchange sessions.
|
||||
- Contains session state derived via TFIT whitebox AES from the client DH key.
|
||||
- Not directly correlated with the raw DH public key bytes.
|
||||
|
||||
4. PER-REQUEST TAIL (352B, bytes 288-351):
|
||||
- 12 bytes session-static overhead [288:300], then a 7-byte random nonce [300:307],
|
||||
then a 1-byte session-specific CBOR tag byte [307].
|
||||
- This 8-byte pattern repeats 3 times at [300:308], [316:324], [332:340],
|
||||
each copy separated by 8B of session-static CBOR overhead.
|
||||
- The 3 copies share the SAME 7-byte random value (XOR between copies is constant).
|
||||
- Bytes [340:348]: partially session-static (likely a counter or CBOR length field).
|
||||
- Bytes [348:352]: 4B per-request unique tail.
|
||||
- The 7-byte random value is NOT a timestamp and NOT a monotonic counter.
|
||||
|
||||
5. 144B VARIANT (map(6)):
|
||||
- One fewer top-level map entry vs 352B (map(6) vs map(7)).
|
||||
- Static header extent: bytes 0-88 (vs 0-127 for 352B).
|
||||
- NO session-bound region: transitions directly to per-request data at byte 89.
|
||||
- 55 bytes of per-request variable data [89:143].
|
||||
- Scattered throughout the capture (req 806–1118); not clustered at session starts.
|
||||
- Represents lightweight/unauthenticated appboot requests without DH session state.
|
||||
""")
|
||||
|
||||
|
||||
if __name__ == "__main__":
|
||||
main()
|
||||
Reference in New Issue
Block a user