OSINT — Letter

Challenge Description

We are given a ZIP file containing three artefacts:

• letter.png — a damaged French envelope (La Poste, Lettre Verte)
• Newspaper_clipping.png — a torn, water-damaged French newspaper front page
• Note.txt — a short handwritten note (transcribed)

Objective: Uncover the full name and age of the person mentioned in the note.
Flag format: THM{Name_Surname_age}

Step 1: Analysing the Envelope

The envelope is a Lettre Verte (La Poste, France) — a green eco-friendly letter service. Key observations:

• Addressed to someone named Édouard G.
• The street/city is torn and illegible
• A La Poste QR stamp is visible top-right
• An orange routing barcode is printed bottom-right by the sorting machine

Decoding the Barcode

The orange barcode at the bottom right is La Poste's proprietary postal sorting barcode, printed by automated sorting machines using fluorescent ink. It encodes the destination postal code.

First attempt: Tried online barcode scanners (ZXing, Inlite, BarcodeScanr) — all failed because it's a proprietary format not supported by standard decoders.

Second attempt: Manually transcribed the bars from the cropped barcode image:

Attempted to decode using Postnet rules (5-bar groups, weighted 7-4-2-1-0):

This gave a candidate postal code of 30136 — but this was incorrect.

Step 2: Analysing the Newspaper

The newspaper is L'Ouest-Éclair — a French republican daily ("Journal Républicain Quotidien"), based in Rennes, Brittany. Visible headlines include:

• "L'œuvre urgente" — an urgent matter
• "Une [catastrophe] sur les côtes du Finistère" — an incident on the Finistère coast
• "Amundsen a-t-il atteint le pôle Nord ?" — "Has Amundsen reached the North Pole?"
• "Les événements du Maroc" — Events in Morocco
• "M. Herriot se déclare solidaire de M. Painlevé" — French political figures

Dating the Newspaper

The Amundsen headline was the key chronological anchor. Roald Amundsen made two Arctic expeditions:

• 1925 — Failed attempt via seaplane (did not reach the pole)
• 1926 — Successful crossing via airship Norge

The phrasing "a-t-il atteint..." ("Has he reached...") suggests uncertainty — consistent with 1925, when the outcome was unknown. The political references to Herriot and Painlevé also confirm the mid-1920s timeframe.

The Finistère Headline

The partially visible headline references a catastrophe on the Finistère coast involving at least two deaths and a rescue operation. Combined with the 1925 date, this pointed to the maritime disaster of May 23, 1925 at Penmarc'h, Finistère.

Step 3: Reading the Note

Translation (key extracts):

• "ton arrière-grand-père" → the subject is Édouard's great-grandfather
• "n'avait même pas l'âge de passer le permis" → he was under 18 at the time
• "le benjamin de l'équipe" → he was the youngest member of the team
• "sur l'eau à ton tour" → "on the water in your turn" → maritime/sailing context
• The letter is signed by Audette (the sender)

Step 4: Historical Research — Gallica & Annales du Sauvetage

With the event pinned to May 23, 1925, Penmarc'h, Finistère, research was conducted using:

• gallica.bnf.fr — BNF's digital archive for L'Ouest-Éclair issues
• Annales du Sauvetage — official French maritime rescue records

First Attempt (Wrong)

Initially proposed Gourlaouen Yves-Marie dit Yvon, 15 ans, mousse based on the rescue reward lists, as he was clearly "le benjamin" — the youngest member of the crew. However this was incorrect.

Correct Answer

Cross-referencing the official Annales du Sauvetage records and Gallica archives for the May 23, 1925 Penmarc'h disaster confirmed the correct person:

Yves-Marie Gourlaouen, age 15 — the youngest rescuer on the Arche-d'Alliance crew, distinguished for his courage during the maritime rescue operation at Penmarc'h on May 23, 1925.

Summary of Clues → Flag

Tools Used

• Manual barcode analysis (Postnet format)
• gallica.bnf.fr (BNF digital archives)
• French postal code lookup
• Historical newspaper research (L'Ouest-Éclair)
• Annales du Sauvetage (maritime rescue records)

Flag