A858DE45F56D9BC9 archive

201309071859 1lwztc

explained decrypted filler

seed 942

Metadata

Post ID
1lwztc
Title
201309071859 → 2013-09-07 18:59 on A858's clock
Posted (UTC)
2013-09-07 14:59:51
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(A858DE45F56D9BC9201309071859) = 230fc4339b0f559f23f9a73f800c2441 (name+title)
GUIDs
4
Filler GUID seed
new Random(942).Next(9) ✓ verified
Run
Run 52 (seed 1,430,705,843) (seed)
Draw
62 · 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
6 · 0
Tags
automated (decryptable)2013Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

CE06D0DBDBDD5B7F D0833DFC3BD96189 39706373EC26568C 383E607ECD9EF0EF A7847B2DCD810417 A942C1227DAE609F DCBEFAD17530C995 6B8DEE9BCCA2DB56 1FE65EB1ED479A70 CDB720008C514AE3 60DF93476DC38915 9A460C2D4C0FAC41 8FBF559522606F73 F0C2943529B19C6B 30605F592C7F4D25 7DC3D964300D9664 DD7643E3FDE2E564
  • Read the ciphertext. Strip whitespace: 272 hex characters = 136 bytes = 17 8-byte 3DES blocks.
  • Derive the key. Password = A858DE45F56D9BC9201309071859 (name+title). Key = MD5(password) = 230fc4339b0f559f23f9a73f800c2441, 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 2c74b00e-2db1-7b61-a604-9aadfbc6ca4a
  2 2ac8ad44-8da6-1c39-b3f3-1784ace8df0f
  3 1c36d85b-320f-1d25-8813-46b32c33361c
  4 79fd0ac5-1865-5895-ba43-98ae890ed634

Explanation

  1. Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 7115. Exactly this sequence comes out of new Random(942).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 62 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