201202011755 p71hu

solved decrypted manual

Poe's quotation from 'Marginalia'. 3DES, key MD5(name).

Metadata

Post ID: p71hu
Title: 201202011755 → 2012-02-01 17:55 on A858's clock
Posted (UTC): 2012-02-02 01:57:30
Timezone: UTC−8 · title 17:55 against posted 01:57 UTC
Author: [deleted]
Account: A858DE45F56D9BC9 main account
Subreddit: r/A858DE45F56D9BC9 the main subreddit
Category: S solved 3DES → text
Content: Quotes
Size: 336 hex characters · 168 bytes
Cipher: 3DES-EDE2 (two-key Triple DES), ECB, PKCS7
Key: MD5(A858DE45F56D9BC9) = 34a14a42e98ff96095af56604e290cae (name)
New here: A Poe quotation from "Marginalia", posted on A858's cake day. (new results)
Sources: arctic-shift · body from arctic-shift
Links: Reddit · Arctic Shift · JSON
Score · comments: 15 · 5
Tags: pre-automation2012Solved special postmanualarctic-onlykey: namequotesfound by this project

From the post to its content

As posted (encrypted)

9346F5E5 6537FC27 F54FCDF6 075E1950 6695DF57 731E6872 04A7F330 DD8E177E B192B07A CDA12573 3D08B1F6 7E033FCA 7DDAFFFA 7E97F304 12FC95B4 25ED1DD3 0F4A0B39 D0D898A9 28CB8EDC 4EE20589 75FB44E7 108E361F A28588B1 374808B6 3C99556E AC71C6C8 04FE31A5 39488623 5DAF4A33 B803776A B54F6EE7 6A067117 DF8010BB 1C238F2E 3FCA52A5 A293C4D7 3DD1C483 9C4ABE30 DF8C2758 D2959382 9BCF7091 C9800008

Decrypt. Key: MD5(name) ECB. 3DES-EDE2, then strip the PKCS7 padding.

Decrypted

In one case out of a hundred a point is excessively discussed because it is obscure; in the ninety-nine remaining it is obscure because it is excessively discussed.

Explanation

Write-up

I have found a solution for p71hu (title 201202011755) which was originally found here (line breaks added for readability):

9346F5E5 6537FC27 F54FCDF6 075E1950 6695DF57 731E6872 04A7F330 DD8E177E
B192B07A CDA12573 3D08B1F6 7E033FCA 7DDAFFFA 7E97F304 12FC95B4 25ED1DD3
0F4A0B39 D0D898A9 28CB8EDC 4EE20589 75FB44E7 108E361F A28588B1 374808B6
3C99556E AC71C6C8 04FE31A5 39488623 5DAF4A33 B803776A B54F6EE7 6A067117
DF8010BB 1C238F2E 3FCA52A5 A293C4D7 3DD1C483 9C4ABE30 DF8C2758 D2959382
9BCF7091 C9800008

It is grouped in 8 hex characters (4 bytes) instead of 16, but that is only the formatting. Put together it is 168 bytes, which decrypts using des-ede-ecb with the same password/key as the other posts from around this time, MD5(A858DE45F56D9BC9) = 34a14a42e98ff96095af56604e290cae, to this:

In one case out of a hundred a point is excessively discussed because it is obscure; in the ninety-nine remaining it is obscure because it is excessively discussed.

The quote is usually attributed to Edgar Allan Poe (from his "Marginalia"). It fits the subreddit rather well. The post went up on 2012-02-02 01:57 UTC, which, as the commenters in the thread noticed, was A858's cake day. I could not find the text quoted anywhere in the sub, on /r/Solving_A858 or in the wiki, so I believe this has not been decrypted before.

All the steps as one command

echo '9346F5E5 6537FC27 F54FCDF6 075E1950 6695DF57 731E6872 04A7F330 DD8E177E B192B07A CDA12573 3D08B1F6 7E033FCA 7DDAFFFA 7E97F304 12FC95B4 25ED1DD3 0F4A0B39 D0D898A9 28CB8EDC 4EE20589 75FB44E7 108E361F A28588B1 374808B6 3C99556E AC71C6C8 04FE31A5 39488623 5DAF4A33 B803776A B54F6EE7 6A067117 DF8010BB 1C238F2E 3FCA52A5 A293C4D7 3DD1C483 9C4ABE30 DF8C2758 D2959382 9BCF7091 C9800008' \
  | xxd -r -p \
  | openssl enc -d -des-ede-ecb -K "$(printf 'A858DE45F56D9BC9' | md5sum | cut -d ' ' -f 1)"; echo

Solution summary

Method: 3DES-ECB, key MD5(name)
Result: Poe, 'Marginalia': 'In one case out of a hundred a point is excessively discussed...'
Explanation: Arctic-only text; posted on A858's cake day (2012-02-01); the community had not seen it
Re-checked: 3DES MD5(name) -> quote