A858DE45F56D9BC9 archive

201309020959 1lk8we

explained decrypted filler

seed 372

Metadata

Post ID
1lk8we
Title
201309020959 → 2013-09-02 09:59 on A858's clock
Posted (UTC)
2013-09-02 05:59:57
Timezone
UTC+4 · title 09:59 against posted 05:59 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(A858DE45F56D9BC9201309020959) = 0a2acd757264e4b62610e294cfc39cc6 (name+title)
GUIDs
4
Filler GUID seed
new Random(372).Next(9) ✓ verified
Run
Run 52 (seed 1,430,705,843) (seed)
Draw
19 · predicted N = 4 ✓
Machine boot
2013-08-14 07:34–10:34 (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)

26A3F4FF601A0643 6F5A96B78B152DBE 7BA7DD1715B882F1 002CD5547FB0BF43 380FC26EC17DEB42 19B01534F9C964CF 0D708ED30573343A E9F65604248632E6 AF91BFE2670A691F 48CC96B7FEE29605 CCED483433FF91F1 15D50F54011FFD17 BF46BB2B8A3590D7 3D129177909E2152 94E5661712BABB00 401577927C9F3125 85C32F9CDC537439
  • Read the ciphertext. Strip whitespace: 272 hex characters = 136 bytes = 17 8-byte 3DES blocks.
  • Derive the key. Password = A858DE45F56D9BC9201309020959 (name+title). Key = MD5(password) = 0a2acd757264e4b62610e294cfc39cc6, 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 925d7b64-0221-0fca-be89-a078b5c07510
  2 fc076580-b764-8b91-b6eb-16f378c2b090
  3 0c84fae9-707b-7a5d-a79f-9bda5450358d
  4 94742408-6ec4-8a01-9c35-192714c129d9

Explanation

  1. Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 0878. Exactly this sequence comes out of new Random(372).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 19 of Run 52 (seed 1,430,705,843): new Random(1430705843), 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 2013-08-14 07:34–10:34).
  3. Conclusion. Filler. The content is fully explained by the two RNGs.

Related

Findings: Mask digit · Count RNG & runs