A858DE45F56D9BC9 archive

201310040714 1nptom

explained decrypted filler

seed 764

Metadata

Post ID
1nptom
Title
201310040714 → 2013-10-04 07:14 on A858's clock
Posted (UTC)
2013-10-04 11:14:53
Timezone
UTC−4 · title 07:14 against posted 11:14 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(A858DE45F56D9BC9201310040714) = 5539887a3da96110b5f8e014fbd684dc (name+title)
GUIDs
4
Filler GUID seed
new Random(764).Next(9) ✓ verified
Run
Run 53 (seed 26,950,390) (seed)
Draw
153 · 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
7 · 0
Tags
automated (decryptable)2013Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

6055A06A4667336E 46B1A60836725253 36517899A5E5D6EC AC1DCC0785460C5A 2C9391E7AA10CFE0 6575861711C53E07 2B415C98E50B6788 62C4D65DE0E35E43 CFE6727075549B70 9F7F1B6C53525993 F9E61A1DB61A5C3C DD6A1AD2E7BCA384 C55930E04669DD62 932B6F65E163A3EC BA1B22623106A1D6 5A071056BDF68604 FB0B096D6B7627C5
  • Read the ciphertext. Strip whitespace: 272 hex characters = 136 bytes = 17 8-byte 3DES blocks.
  • Derive the key. Password = A858DE45F56D9BC9201310040714 (name+title). Key = MD5(password) = 5539887a3da96110b5f8e014fbd684dc, 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 2397df91-5827-7a72-bad0-2167ef7b8438
  2 562fd63f-05ef-8c03-bdea-22b15c59049b
  3 c3ca1435-8b5f-7f8b-9ee2-0752103de70e
  4 c3d06355-0bd4-5fcf-b489-f6b8ddd2693a

Explanation

  1. Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 7875. Exactly this sequence comes out of new Random(764).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 153 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