A858DE45F56D9BC9 archive

201309061859 1luu0r

explained decrypted filler

seed 90

Metadata

Post ID
1luu0r
Title
201309061859 → 2013-09-06 18:59 on A858's clock
Posted (UTC)
2013-09-06 14:59:52
Timezone
UTC+4 · title 18:59 against posted 14:59 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(A858DE45F56D9BC9201309061859) = 2fc72aab83c19ed23a444bd24654a739 (name+title)
GUIDs
4
Filler GUID seed
new Random(90).Next(9) ✓ verified
Run
Run 52 (seed 1,430,705,843) (seed)
Draw
54 · 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
1 · 0
Tags
automated (decryptable)2013Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

CABD4B41C73E5149 A478B9B8B31C8418 A60CB7389AE79C6D AE1CF6AA0EBFBBA0 D45E68633133978E 4EDF7DEF1142FFBF 2AD5BAB86A13A12E F068F15E2D05D5F2 1823BF772E8426F1 C38096230D38CB8F A53B18F4695A62B8 07BACE94ABC8FB6D 49F3FB41019B656F 0A139B8D330C8D11 E69AFF7C1799021B FD7C695467EA8C40 B6090719E8F6891A
  • Read the ciphertext. Strip whitespace: 272 hex characters = 136 bytes = 17 8-byte 3DES blocks.
  • Derive the key. Password = A858DE45F56D9BC9201309061859 (name+title). Key = MD5(password) = 2fc72aab83c19ed23a444bd24654a739, 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 8e638491-117e-6516-ba10-d294e0277c2d
  2 c5112534-14f8-2ce2-83d0-46534732932d
  3 1581ef4c-2237-6d45-83e2-f7269401a228
  4 0dda7a3d-563b-6632-95a8-6f540809a532

Explanation

  1. Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 6266. Exactly this sequence comes out of new Random(90).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 54 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