A858DE45F56D9BC9 archive

201309142059 1mep31

explained decrypted filler

seed 128

Metadata

Post ID
1mep31
Title
201309142059 → 2013-09-14 20:59 on A858's clock
Posted (UTC)
2013-09-15 00:59:57
Timezone
UTC−4 · title 20:59 against posted 00:59 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(A858DE45F56D9BC9201309142059) = 9019c64230546797eca1678539d550be (name+title)
GUIDs
4
Filler GUID seed
new Random(128).Next(9) ✓ verified
Run
Run 53 (seed 26,950,390) (seed)
Draw
56 · 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
1 · 0
Tags
automated (decryptable)2013Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

B598441A26D3A491 E5DBF3FC32143A0A C81128091E6D1404 2B139421CA98D2F4 B8BDD39E65698FED F6633F11BF916488 B443B23402FFA236 20079FD21F260DE9 3FCCF1EFCF2133DC 47837A477D69BA25 8EC76B7B0CE91CC8 6E9858A5AE9B9A5A 43E090C887C6C925 A3C365B5FBE7C4B4 7F8D615469A4443E 83697A7C088D69A1 0A4011E4D8378221
  • Read the ciphertext. Strip whitespace: 272 hex characters = 136 bytes = 17 8-byte 3DES blocks.
  • Derive the key. Password = A858DE45F56D9BC9201309142059 (name+title). Key = MD5(password) = 9019c64230546797eca1678539d550be, 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 5069942f-074d-5e6b-9ac0-057442426a15
  2 d15fc384-633e-3062-9979-660b8d4ad027
  3 3184b767-9584-2ff5-896a-a6f20547f27b
  4 038c5d90-68d3-70cc-8707-ea09e7046513

Explanation

  1. Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 5327. Exactly this sequence comes out of new Random(128).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 56 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