A858DE45F56D9BC9 archive

201309140259 1md6ae

explained decrypted filler

seed 138

Metadata

Post ID
1md6ae
Title
201309140259 → 2013-09-14 02:59 on A858's clock
Posted (UTC)
2013-09-14 06:59:58
Timezone
UTC−4 · title 02:59 against posted 06:59 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(A858DE45F56D9BC9201309140259) = c5da319ac31d00e8179e3ea493c00ede (name+title)
GUIDs
4
Filler GUID seed
new Random(138).Next(9) ✓ verified
Run
Run 53 (seed 26,950,390) (seed)
Draw
38 · 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
5 · 0
Tags
automated (decryptable)2013Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

4E8D58326E0BAD74 FABD736F76E3D0E8 E9926EC2BD72007B 5DF1087B9766B68C C654A56D58048B8B 0556993500535FD2 08E6ADC06C2E3DC8 1E205DBA207665E2 E875454AAA4A2BA2 36588E3779CED07D 9FE592D2F84CF207 92AB400162D7EA74 15EEE78DA225F1BF 467EFA7355D6D8B6 C3DF64BBCF1C78F3 49667ABE80CBF73E 308526A18D87F393
  • Read the ciphertext. Strip whitespace: 272 hex characters = 136 bytes = 17 8-byte 3DES blocks.
  • Derive the key. Password = A858DE45F56D9BC9201309140259 (name+title). Key = MD5(password) = c5da319ac31d00e8179e3ea493c00ede, 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 3b9f7be1-1535-76a5-9792-ea1e858119c0
  2 713fdc8e-feff-2841-920e-834f65ff60dc
  3 13201e9d-54de-28de-94b3-6089500b86f5
  4 233e0655-2ea8-04ab-aeaf-a09e5c6d65d5

Explanation

  1. Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 7220. Exactly this sequence comes out of new Random(138).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 38 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