201309091859 1m1b6r

explained decrypted filler

seed 708

Metadata

Post ID: 1m1b6r
Title: 201309091859 → 2013-09-09 18:59 on A858's clock
Posted (UTC): 2013-09-09 14:59:49
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: 528 hex characters · 264 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9201309091859) = c8b6d5c0cc3e6800edb6d39fff207365 (name+title)
GUIDs: 8
Filler GUID seed: new Random(708).Next(9) ✓ verified
Run: Run 52 (seed 1,430,705,843) (seed)
Draw: 78 · predicted N = 8 ✓
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 · 0
Tags: automated (decryptable)2013Encrypted masked GUID listkey: name+titlerun: seed

From the post to its content

As posted (encrypted)

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

Read the ciphertext. Strip whitespace: 528 hex characters = 264 bytes = 33 8-byte 3DES blocks.
Derive the key. Password = A858DE45F56D9BC9201309091859 (name+title). Key = MD5(password) = c8b6d5c0cc3e6800edb6d39fff207365, used as a two-key 3DES key.
Decrypt. 3DES-EDE2 in ECB mode, then strip the PKCS7 padding. The plaintext is 8 GUIDs as hex (shown below).

Decrypted: GUID list

  1 7ef9b02a-6a6e-59b2-bc1b-d2e0b45694dd
  2 3e8dd74b-14ef-5fec-9e5c-bc333530ffd6
  3 9e512b2a-6eaa-52ca-bdea-0fb0b264cce8
  4 36d7b75a-a302-68b8-a641-85b993a2851b
  5 142575a4-0dd6-7b84-aa1f-c5f2c9ee40a9
  6 5f1b4788-9023-22e8-bf8d-47da49fa14de
  7 2c3e36d6-db44-1ee9-a280-f543b73b9d73
  8 e2ac0a38-acf7-5751-8900-3cfafad04b23

Explanation

Explain the mask digits. The version nibble (13th hex digit) of each GUID, read in order, gives 55567215. Exactly this sequence comes out of new Random(708).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.
Explain the count. This post is draw 78 of Run 52 (seed 1,430,705,843): new Random(1430705843), 4·Next(1,12) per post. The RNG predicts N = 8; the post has N = 8 ✓. The seed is the machine's uptime in ms when the app started (boot 2013-08-14 07:34–10:34).
Conclusion. Filler. The content is fully explained by the two RNGs.

Metadata

From the post to its content

As posted (encrypted)

Decrypted: GUID list

Explanation

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