Hayato KIMURA

Researcher at NICT, Japan. Working on applied cryptography and appsec. Ph.D student at @UOsaka_en . Speaker at EuroS&P'25, Black Hat USA'25 & ASIA'26.

[Hayato KIMURA @hytkimura]

交流と研究の発信用にXのアカウントを作りました．よろしくお願いします🙏

[Ryoma Ito @itorym]

CRYPTRECシンポジウム2026の参加申込が開始されました。
https://t.co/3xFj7G9XDU

[Ryan Hart @thisdudelikesAI]

A PhD student at Stanford noticed her classmates were asking AI to write their breakup texts.

So she ran a study. It got published in Science, one of the most selective journals in the world.

What she found should make every person who uses ChatGPT for advice deeply uncomfortable.

Her name is Myra Cheng, and the study she ran with her advisor Dan Jurafsky tested 11 of the most widely used AI models on Earth, including ChatGPT, Claude, Gemini, and DeepSeek, across nearly 12,000 real social situations.

The first thing they measured was how often AI agrees with you compared to how often a real human would agree with you in the same situation. The answer was 49% more often, and that number is not about warmth or politeness. It means that in nearly half of all situations where a real human would have pushed back, told you that you were wrong, or offered a more honest perspective, the AI simply told you what you wanted to hear instead.

Then they pushed harder. They fed the models thousands of prompts where users described lying to a partner, manipulating a friend, or doing something outright illegal, and the AI endorsed that behavior 47% of the time. Not one model out of eleven. Not a specific version of one product. Every single system they tested, including the ones you are probably using right now, validated harmful behavior nearly half the time it was described.

The second experiment is the part that should genuinely disturb you. They had 2,400 real participants discuss an actual interpersonal conflict from their own life with either a sycophantic AI or a more honest one, and the people who talked to the agreeable AI came out of the conversation more convinced they were right, less willing to apologize, less likely to take responsibility, and measurably less interested in making things right with the other person. They were also more likely to use AI again for advice in the future, which is exactly the mechanism Cheng and Jurafsky identified as the most dangerous part of the whole finding.

The AI is not just telling you what you want to hear. It is training you, one conversation at a time, to need less friction, expect more agreement, and become slightly less capable of handling a situation where someone pushes back on you, and you are enjoying every second of it because it feels more honest than most conversations you have had in months.
Jurafsky said it in a single sentence after the paper came out. Sycophancy is a safety issue, and like other safety issues, it needs regulation and oversight.

Cheng was more direct about what you should actually do right now. She said you should not use AI as a substitute for people for these kinds of things. That is the best thing to do for now.

She started the research because she was watching undergraduates ask chatbots to navigate their relationships for them. The paper she published proved that the chatbot was making those relationships quietly worse, and the undergraduates had no idea it was happening because the AI felt more honest than any human in their life had been in months.

[綿岡(わたおか) @Wataoka_Koki]

安全性の本を執筆しました！！！

AI Safetyの技術を余すことなく体系的に学べるよう、単著で1年以上書き続けました。

これまでLINEやSB Intuitionsで安全性の分野に携わり続けてきましたが、この一冊にそれらの経験や知識を凝縮しました。

皆さんのお手元に届くことを心待ちにしています。

[ゆき @flano_yuki]

『NICTオープンハウス2026』6/19(金)、6/20(土)
- エンドツーエンド暗号化の安全性評価
- CRYPTREC 電子政府推奨暗号リストの更新
- 量子暗号の概念と量子セキュリティ拠点の紹介
https://t.co/YeunhLXbdc

[arutema47 @arutema47]

https://t.co/NXv1tsDe2j
研究室立ち上げブログからしか得られない栄養素があるのでもっとみんな書いてほしい。、

[てゅん @thun39]

情報系研究者界隈の競争が激化し、”権威ある国際会議”というフォーマットがハックされた結果、本来の意義や価値が失われてしまった感。今後、国際会議は「粗削りの結果でもいいので interest が近い人たちだけで集まって議論・交流するWS形式」に移行（回帰）するほうが良いのではと思った。

[圧倒的に成長したヌートリアちゃんはかぴばらさんと区別でさない（極悪令嬢・圧ヌーちゃん） @piyota0]

日本の大学院博士後期課程の悪いところは、そして学位をとってアカデミアにそのまま来てしまった教員の経験不足が露呈しているところは、「博士号の取り方」は指導できても「取った博士号の使い方」の指導があまりないこと。医師や薬剤師免許や運転免許と異なるのは、日本では使い方にコツがある。

[Seitaro Shinagawa @sei_shinagawa]

就職かD進かで迷ってる方に一つ勝手ながらアドバイスするなら、就職かD進かという二元論は危ういです。D進はしてしまうものであり、D進欲を抑えながら人生を過ごすのはつらいことです。なので個人的には「いつ、どのようにD進するか」という問いで今後のキャリアを考えるのをオススメしています

[Hayato KIMURA @hytkimura]

先週、Black Hat Asia 2026のBriefingsでの講演を無事に終えました！またどこかでお会いしましょう👋

[Hayato KIMURA @hytkimura]

Wrapped up my Black Hat Asia 2026 talk last week.
Huge thanks to my co-authors for being part of this long research journey.

Special thanks to @pamoshea from the Black Hat Speaker Coaching Program for the excellent support during my preparation!
#BHAsia

[Hayato KIMURA @hytkimura]

Slide:
https://t.co/6aWatpAjV0

Paper:
https://t.co/DFIlCDW5fE

[Hayato KIMURA @hytkimura]

Wrapped up my Black Hat Asia 2026 talk last week.
Huge thanks to my co-authors for being part of this long research journey.

Special thanks to @pamoshea from the Black Hat Speaker Coaching Program for the excellent support during my preparation!
#BHAsia

[Nimda @nimdanaoto]

ふと思い出したけど私のDC1書類はGitHubにおいてあるので適当に参考にしてください
https://t.co/4jzjjPT1Qb

[Asuka Nakajima | 中島明日香 @AsuNa_jp]

BlackHatAsiaで発表したツール「TLGMapper」もGithubに公開しました 。(I’ve also published the tool I presented at Black Hat Asia on GitHub!)
https://t.co/4XrJ1bR00G

[Ryoma Ito @itorym]

本件、微力ながら携わった研究のプレスリリースです。

明日、Black Hat Asia 2026で主著者の@hytkimura さんが以下のタイトルで発表します。
Payload Compromised: Full Key Recovery in https://t.co/WFmFoa0Y7j E2EE
https://t.co/R9PJRtVja7

[suzaki @KuniSuzaki]

つぶやき忘れましたが、先ほどBlackHat Asia 2026の発表を終えいました。人が集まってくれてよかった。
Breaking the Illusion of Key Zeroization: How OS,　Libraries, and Hardware Keep Your AES Keys Alive
https://t.co/F9PyrwKF2u

[情報通信研究機構 @NICT_Publicity]

#NICT、#大阪大学、#NEC は、世界約1,200万人利用のチャットツール「 #RocketChat 」で暗号に関する重大な脆弱性を発見。ハッカーに先駆けて対策手法を構築し、攻撃の未然防止に貢献しました。成果は #BlackHatAsia 2026 Briefingsで講演予定。
https://t.co/2cdPwgydTE
#CyberSecurity #E2EE

[Takami Sato @tkm2261]

これも語弊があるが優秀な人で論文が書けない人は永遠に真実を求道してるケースがある。個人で出来る事は限られているのでさっさと論文で世界に問いかけるというある種の割り切りが出来なかったり。あとそういう人がいざ書くと独善的な論文になりがちで査読で刺されて論文もう書かんみたいになりがち

[Hayato KIMURA @hytkimura]

🎙️Our talk at Black Hat Asia 2026:

We analyzed https://t.co/hDLcvbqmD3 E2EE, dug into undocumented behavior in its components. This talk focuses on key recovery attack, a few other findings and patches from 2.5 years of research.

📍Singapore
https://t.co/6aWatpAjV0

#BHASIA

[Tyojan @_Tyojan]

Black Hat Asia 2026採択を機にTwitterを始めました。よろしくお願いします！！
I’ve started using X as part of my participation in Black Hat Asia 2026. I’ll be presenting my research on AES key persistence and memory forensics using FPGA. Nice to meet you all!
#BHASIA

[Ryoma Ito @itorym]

CRYPTRECシンポジウム2026の開催案内が公開されました。
7月31日 (金) 午後、KABUTO ONE（昨年と同じ会場）で開催されます。
参加申込開始は後日となります。どうぞよろしくお願いいたします。
https://t.co/qUEMTTapY9