A858DE45F56D9BC9 archive

201309080059 1lxmzv

explained decrypted filler

seed 663

Metadata

Post ID
1lxmzv
Title
201309080059 → 2013-09-08 00:59 on A858's clock
Posted (UTC)
2013-09-07 20:59:51
Timezone
UTC+4 · title 00:59 against posted 20:59 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(A858DE45F56D9BC9201309080059) = 12e9eca5f392955e282d98031cd35fe5 (name+title)
GUIDs
4
Filler GUID seed
new Random(663).Next(9) ✓ verified
Run
Run 52 (seed 1,430,705,843) (seed)
Draw
64 · 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
4 · 1
Tags
automated (decryptable)2013Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

E03461E648EA89C6 B0760F279E0DDC9E 1E8241B8C9CD0231 5A4DB3D830B31D22 49A808540F318028 CA4B8A05CF235564 FFB4B0C2985267E4 B94020F48735A63C 6A6115493E57CAB4 B43B017928A71421 9F13961A42EEDB17 6F1CC3F352014AB5 C3F8B7993B82A1FC EF848BB1E3D37121 3730C9DB2D71CEE0 F46B12D081100F37 DF61E87CBADFE1FE
  • Read the ciphertext. Strip whitespace: 272 hex characters = 136 bytes = 17 8-byte 3DES blocks.
  • Derive the key. Password = A858DE45F56D9BC9201309080059 (name+title). Key = MD5(password) = 12e9eca5f392955e282d98031cd35fe5, 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 20d47417-00b4-05da-ae19-ac92711fbd08
  2 43537314-fc35-3974-b4e6-0a53c3e180cc
  3 3e8883bc-ca42-1078-b4b5-816901bced9c
  4 2c8caf7c-432b-0936-93d2-89ce2b6a4d41

Explanation

  1. Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 0310. Exactly this sequence comes out of new Random(663).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 64 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