CTF{xk4r_3t4pt_h00r_G03d_b3z1g} this flag is wrong and I believe that there are a few extra letters in the leet speak of this dutch flag, what could possibly be the correct flag

Claude Opus 4.7

Answer: The correct flag is most likely CTF{k4r_3t4p_h00r_G03d_b3z1g}, obtained by removing the extra 'x' from 'xk4r' and the extra trailing 't' from '3t4pt'.

After reviewing GPT-5.5's response, I'm maintaining my original position. We agree on the core analysis: the flag is Dutch leet speak with extra letters, the ending 'h00r_G03d_b3z1g' clearly decodes to 'hoor goed bezig' (a Dutch encouragement meaning 'doing well/keep it up'), and the suspicious parts are 'xk4r' and '3t4pt'. Where we differ is which letters to remove from '3t4pt'. GPT-5.5 suggests removing the leading '3' to get 't4pt' → 'tapt' (taps), while I suggest removing the trailing 't' to get '3t4p' → 'etap' (stage/leg). I find my interpretation more compelling for two reasons: (1) The number '3' as leet for 'e' at the start of a word is a very common and intentional leet speak pattern — removing it would be unusual since it's clearly a deliberate stylization. The trailing 't', however, looks like a genuine typo/extra letter. (2) 'kar etap' could relate to a cycling/racing context (kar = cart, etap(pe) = stage), and 'hoor, goed bezig!' fits as a cheer — 'cart stage, hey, doing well!' This is more coherent in a CTF context than 'kar tapt' (cart taps). Also, I disagree with GPT-5.5's suggestion to lowercase 'G03d' — the user only mentioned extra letters, not case changes, so we shouldn't modify what isn't flagged as wrong.

GPT-5.5

Answer: The most likely corrected flag is `CTF{k4r_t4pt_h00r_G03d_b3z1g}`.

I would not adopt Claude Opus 4.7’s proposed `CTF{k4r_3t4p_h00r_G03d_b3z1g}`, because removing the final `t` from `3t4pt` leaves `3t4p`, which decodes to something like `etap`, not a natural Dutch word in this context. The cleaner deletion-only correction is to remove the extra `x` from `xk4r` and the extra `3` from `3t4pt`. That turns the decoded text from `xkar etapt hoor Goed bezig` into `kar tapt hoor Goed bezig`. While still a bit quirky, `tapt` is an actual Dutch verb form meaning “taps/pours,” so `kar tapt` is more plausible than `kar etap`. I would also preserve the original capitalization of `G03d` unless the challenge specifically says flags must be lowercase, because the user’s stated issue is extra letters rather than casing. So my best candidate is `CTF{k4r_t4pt_h00r_G03d_b3z1g}`.

Grok 4.20 (changed mind)

Answer: The correct flag is CTF{k4r_3t4p_h00r_G03d_b3z1g}.

The provided string CTF{xk4r_3t4pt_h00r_G03d_b3z1g} is described as containing a few extra letters in its Dutch leetspeak. The last three segments clearly decode to "hoor goed bezig," a common Dutch expression equivalent to "hear, well done" or "you're doing great." The first two segments are the problem: xk4r_3t4pt does not form recognizable Dutch words. Removing the leading 'x' yields k4r ("kar," meaning cart or car) and removing the final 't' from 3t4pt yields 3t4p ("etap," short for etappe, a stage or leg of a race). This produces the coherent if slightly terse racing-related phrase "kar etap hoor goed bezig." GPT-5.5's alternative of removing the leading '3' instead creates t4pt ("tapt"), resulting in "kar tapt hoor goed bezig," which is grammatically possible but far less idiomatic or contextually plausible for a CTF flag. Claude Opus 4.7's deletion choices better match Dutch vocabulary related to stages or journeys while requiring only the "few extra letters" promised. CTF flags frequently use shorthand or proper nouns, so "kar etap" fits a cycling or rally context where one might congratulate a participant mid-stage. No other minimal-letter removal yields a cleaner Dutch phrase.

GLM 5.1 (changed mind)

Answer: The correct flag is likely CTF{k4r_3t4p_h00r_G03d_b3z1g}, with the extra letters 'x' and 't' removed from the original leet speak.

After reviewing the other models' analyses, I find Claude Opus 4.7's reasoning more compelling. The original flag CTF{xk4r_3t4pt_h00r_G03d_b3z1g} clearly contains Dutch leet speak where 'h00r_G03d_b3z1g' decodes to 'hoor goed bezig' (meaning 'you're doing well'). The hint states there are 'a few extra letters.' Examining the suspicious parts: - 'xk4r' has an unnecessary 'x' prefix — removing it gives 'k4r' (kar = cart) - '3t4pt' has a trailing 't' that seems superfluous — removing it gives '3t4p' (etap, short for etappe = stage) Claude's solution CTF{k4r_3t4p_h00r_G03d_b3z1g} yields 'kar etap hoor goed bezig,' which, while not perfectly idiomatic Dutch, contains recognizable elements. GPT-5.5's alternative of removing '3' instead of 't' produces 't4pt' (tapt), which is less meaningful in this context. The trailing 't' in '3t4pt' appears to be the extra letter referred to, as 'etap' is a recognizable truncation of 'etappe' (stage), whereas 'etapt' is not a word form.

DeepSeek V3.2 (changed mind)

Answer: The correct flag is CTF{k4r_3t4p_h00r_g03d_b3z1g}, removing the extra 'x' from 'xk4r' and 't' from '3t4pt' while lowercasing for consistency.

The original flag CTF{xk4r_3t4pt_h00r_G03d_b3z1g} decodes to Dutch leet speak where 'h00r' is 'hoor', 'G03d' is 'Goed', and 'b3z1g' is 'bezig', forming the common phrase 'hoor goed bezig' (meaning 'well done'). The first part 'xk4r_3t4pt' is problematic; 'xk4r' has an extra 'x' before 'k4r' (leet for 'kar'), and '3t4pt' has an extra 't' after '3t4p' (leet for 'etap', meaning stage). The user hint specifies 'a few extra letters', so removing 'x' and 't' yields 'k4r_3t4p', which decodes to 'kar etap'. While 'kar etap hoor goed bezig' is not idiomatic Dutch, it aligns with CTF puzzle logic where leet speak is often used creatively. Claude Opus 4.7's answer convincingly identifies these extra letters and provides a clear correction. I lowercased 'G03d' to 'g03d' for consistency, as CTF flags typically use lowercase unless specified otherwise. GPT-5.5's alternative, 'CTF{k4r_t4pt_h00r_g03d_b3z1g}', involves removing the '3' which is part of the leet encoding for 'e', making it less faithful to the original leet structure. Thus, Claude's approach best fits the hint and common CTF practices.

Gemini 3.1 Pro

Answer: The correct flag is `CTF{k4pt_h00r_G03d_b3z1g}`, which is discovered by literally removing the leetspeak letters that spell the word "extra" (`3xtr4`) from the scrambled first half of the string.

While Claude and GPT-5.5 correctly decoded the second half of the flag as 'hoor Goed bezig' (a common Dutch phrase meaning 'doing a great job'), their attempts to fix the first half relied on arbitrary letter deletions that resulted in awkward, non-idiomatic Dutch. They completely missed the literal wordplay hidden in the hint. The prompt explicitly states that there are 'extra letters'. In typical CTF fashion, this is not just a vague clue—it is a literal instruction. The letters spelling the word 'extra' have been mathematically injected into the string. If we translate 'extra' into leetspeak, we get `3xtr4`. Let's look at the first two words of the provided flag: `xk4r_3t4pt`. If we extract exactly the letters `3`, `x`, `t`, `r`, and `4` from this segment, the breakdown is flawless: - Removing `x` and `r` from `xk4r` leaves exactly `k4`. - Removing `3`, `t`, and `4` from `3t4pt` leaves exactly `pt`. By pushing the remaining letters together, we get `k4pt`, which is leetspeak for the valid Dutch word 'kapt' (from the verb 'kappen', meaning to chop, cut, or stop). This precise 5-letter cryptographic extraction is far too perfect to be a coincidence, proving that the original flag was `CTF{k4pt_h00r_G03d_b3z1g}` before the 'extra' letters were spliced into it.

Final Summary

The AI Roundtable identified the flag as Dutch leet speak decoding to the phrase "hoor goed bezig" (doing well). Claude Opus 4.7, Grok 4.20, GLM 5.1, and DeepSeek V3.2 reached a consensus that removing the 'x' and 't' characters reveals "kar etap," referring to a travel stage. Gemini 3.1 Pro provided a brilliant but solitary dissent, arguing the hint "extra" meant literally removing the letters "3xtr4" to find a hidden word.

4 of 6 models agreed