A858DE45F56D9BC9 archive

201309132159 1mcrtt

explained decrypted filler

seed 379

Metadata

Post ID
1mcrtt
Title
201309132159 → 2013-09-13 21:59 on A858's clock
Posted (UTC)
2013-09-14 01:59:58
Timezone
UTC−4 · title 21:59 against posted 01:59 UTC
Author
[deleted]
Account
A858DE45F56D9BC9 main account
Subreddit
r/A858DE45F56D9BC9 the main subreddit
Category
F3 filler: 3DES(name/title) → GUID list, seed known
Size
272 hex characters · 136 bytes
Cipher
3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key
MD5(A858DE45F56D9BC9201309132159) = 00853240b9df46afb21ad02d033d386f (name+title)
GUIDs
4
Filler GUID seed
new Random(379).Next(9) ✓ verified
Run
Run 53 (seed 26,950,390) (seed)
Draw
33 · predicted N = 4 ✓
Machine boot
2013-09-12 09:30–10:30 (seed = uptime at app start)
Sources
community-archive, arctic-shift · body from community-archive
Links
Reddit · Arctic Shift · JSON
Score · comments
3 · 0
Tags
automated (decryptable)2013Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

E45DA29682DB5BD2 F77C5DC8C58F35A9 F65D6B222745F257 0254D172737E8242 E919639CFA81AEAD 76B9E4040DC6919D 55D535CAAD7E7376 B9FE87F137388143 136F92359CF80916 C7D7E07FC7FBC9A4 21D8265F4A46CC83 2D44126E8C4E441A 8F22A6689D24C5A5 B3C7FE71993C799D 1FF8373489286602 FB160CE2E5A10F32 6707CC0446143A0B
  • Read the ciphertext. Strip whitespace: 272 hex characters = 136 bytes = 17 8-byte 3DES blocks.
  • Derive the key. Password = A858DE45F56D9BC9201309132159 (name+title). Key = MD5(password) = 00853240b9df46afb21ad02d033d386f, used as a two-key 3DES key.
  • Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 4 GUIDs as hex (shown below).

Decrypted: GUID list

  1 8be52659-c88a-6bcb-a3f1-d882f5cf2c33
  2 5aaf7cd2-3ce8-0796-938d-059bc703d846
  3 ef671914-e4ae-6be5-8174-3a6edecded02
  4 6a4b1740-9114-4b75-90d3-fe12ca708aca

Explanation

  1. Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 6064. Exactly this sequence comes out of new Random(379).Next(9): the per-post millisecond seed of the mask generator. The other 30 hex digits of each GUID are Guid.NewGuid() output and carry no message.
  2. Explain the count. This post is draw 33 of Run 53 (seed 26,950,390): new Random(26950390), 4·Next(1,12) per post. The RNG predicts N = 4; the post has N = 4 ✓. The seed is the machine's uptime in ms when the app started (boot 2013-09-12 09:30–10:30).
  3. Conclusion. Filler. The content is fully explained by the two RNGs.

Related

Findings: Mask digit · Count RNG & runs