DeACED

Dump and inspect Java Object Serialization (0xAC 0xED) streams — and Java RMI packet contents — in a clear, human-readable, hierarchical form.

DeACED (a nod to the AC ED stream magic, and to de-serialization) is a small, dependency-free Python library and CLI. It is a port of SerializationDumper by Nicky Bloor, with several correctness fixes (see NOTICE).

Install

pip install deaced            # once published
# or from source:
pip install .

CLI

deaced -r dump.bin                 # raw serialized file
cat dump.bin | deaced -r -         # from stdin
deaced -x aced0005740004414243...  # hex on the command line
deaced -f hexdump.txt              # file of hex-ascii bytes
deaced -r dump.bin --offsets       # prefix each line with '@<byte-offset>|'
deaced -r dump.bin -o out.txt      # write to a file
deaced -r dump.bin -F json         # structured, machine-readable JSON
deaced -r dump.bin -F pretty       # compact, human-readable data tree

Example:

$ deaced -x aced0005740004414243447071007e0000

STREAM_MAGIC - 0xac ed
STREAM_VERSION - 0x00 05
Contents
  TC_STRING - 0x74
    newHandle 0x00 7e 00 00
    Length - 4 - 0x00 04
    Value - ABCD - 0x41424344
  TC_NULL - 0x70
  TC_REFERENCE - 0x71
    Handle - 8257536 - 0x00 7e 00 00

Library

from deaced import dump, parse

data = open("dump.bin", "rb").read()

print(dump(data))                       # text dump (default)
print(dump(data, offsets=True))         # with '@<offset>|' prefixes
print(dump(data, format="json"))        # structured JSON
print(dump(data, format="pretty"))      # compact human-readable tree

tree = parse(data)                      # the semantic AST (deaced.model.Stream)

Why a port?

Removes the JVM dependency (the original is a Java jar), runs anywhere Python does, integrates into Python tooling, and fixes real bugs in the original — most notably the (long)/(double) integer-shift bug (0xFFFFFFFFFFFFFFFF was shown as -4294967297 instead of -1). See NOTICE for the full list.

Safety

DeACED is built to inspect untrusted, attacker-controlled serialization streams (that is the usual reason to dump one), so:

• It never deserializes Java objects. DeACED only reads and decodes the byte stream into a descriptive tree — it does not load classes, instantiate objects, or invoke readObject. The classic Java deserialization gadget chains cannot fire through it.
• It fails cleanly on malformed input. Truncated or structurally-invalid streams raise a SerDumpError carrying the byte offset; negative lengths/counts are rejected rather than driving huge allocations; deeply nested streams raise an error instead of crashing the interpreter.

Resource use is still proportional to input size — apply your own limits when dumping data straight off the network. See SECURITY.md.

Development

pip install -e ".[dev]"
pytest            # tests (tiny synthetic fixtures)
ruff check .
ruff format --check .
mypy

Contributing

Contributions welcome — see CONTRIBUTING. The stream "rebuild" (-b) mode of the original is intentionally not ported (see NOTICE).

Credits & license

Python port by Alexander Gmar (@gmarav) — github.com/gmarav/DeACED. Based on SerializationDumper by Nicky Bloor (@NickstaDB). Licensed under the MIT License; port © 2026 Alexander Gmar, original © 2017 Nicky Bloor.