{"guid":"23d59026-ab98-4f6c-a46d-0bb3e1788a67","title":"Squeezing a key through a carry bit","subtitle":null,"slug":"34c3-9021-squeezing_a_key_through_a_carry_bit","link":"https://fahrplan.events.ccc.de/congress/2017/Fahrplan/events/9021.html","description":"The Go implementation of the P-256 elliptic curve had a small bug due to a misplaced carry bit affecting less than 0.00000003% of field subtraction operations. We show how to build a full practical key recovery attack on top of it, capable of targeting JSON Web Encryption.","original_language":"eng","persons":["Filippo Valsorda"],"view_count":2106,"promoted":false,"date":"2017-12-27T00:00:00.000+01:00","release_date":"2017-12-28T01:00:00.000+01:00","updated_at":"2026-04-14T12:00:06.621+02:00","tags":["34c3","9021","Security"],"length":3001,"duration":3001,"thumb_url":"https://static.media.ccc.de/media/congress/2017/9021-hd.jpg","poster_url":"https://static.media.ccc.de/media/congress/2017/9021-hd_preview.jpg","timeline_url":"https://static.media.ccc.de/media/congress/2017/23d59026-ab98-4f6c-a46d-0bb3e1788a67-timeline.jpg","thumbnails_url":"https://static.media.ccc.de/media/congress/2017/23d59026-ab98-4f6c-a46d-0bb3e1788a67-thumbnails.vtt","frontend_link":"https://media.ccc.de/v/34c3-9021-squeezing_a_key_through_a_carry_bit","url":"https://api.media.ccc.de/public/events/23d59026-ab98-4f6c-a46d-0bb3e1788a67","conference_title":"34C3: TUWAT","conference_url":"https://api.media.ccc.de/public/conferences/34c3","related":[{"event_id":4762,"event_guid":"b036385c-ec1a-44e5-ae48-af703ce9b5d3","weight":13},{"event_id":4763,"event_guid":"2ef3b60f-6e5c-4c23-a145-d263685ec13e","weight":53},{"event_id":4766,"event_guid":"19b7e5d7-bba7-46da-afbc-f16d43fe395f","weight":51},{"event_id":4781,"event_guid":"44e7cb13-011e-4242-b26a-1edf4ac15b83","weight":44},{"event_id":4784,"event_guid":"65a25dfd-56dd-4e87-a910-334e2dc25a9c","weight":64},{"event_id":4794,"event_guid":"a2887b4a-0c9d-4220-a52f-c65c20ae25d7","weight":41},{"event_id":4795,"event_guid":"722ce759-9cde-4e3b-8db5-5a97aa9673d9","weight":58},{"event_id":4796,"event_guid":"ff24373e-ebe2-4077-9db0-eae5ab003538","weight":41},{"event_id":4797,"event_guid":"c7b3314c-165c-446d-963c-609922ea990f","weight":46},{"event_id":4810,"event_guid":"c1acc5c2-58b2-4ed5-a504-351b8b93c171","weight":48},{"event_id":4817,"event_guid":"be19fbe3-e825-4e67-93f9-a6aeda2e31af","weight":51},{"event_id":4818,"event_guid":"c02f6777-5e55-46ca-8d60-1810a8d5f3c7","weight":51},{"event_id":4826,"event_guid":"16645200-2036-4a3c-a44d-a5ff44ac2991","weight":57},{"event_id":4830,"event_guid":"5cf8c222-47d3-4741-9324-be182b4d0fb8","weight":53},{"event_id":4832,"event_guid":"275f85de-d612-4440-8755-85dee5912f12","weight":43},{"event_id":4833,"event_guid":"e1a60f7b-6a56-4dce-ab3a-c686fa940aa8","weight":49},{"event_id":4844,"event_guid":"5c5e888e-4556-405b-a205-e59b97db99e1","weight":42}],"recordings":[{"size":null,"length":null,"mime_type":"application/x-subrip","language":"eng","filename":"34c3-9021-eng-deu-Squeezing_a_key_through_a_carry_bit.en.srt","state":"complete","folder":"","high_quality":true,"width":null,"height":null,"updated_at":"2021-02-21T17:46:58.946+01:00","recording_url":"https://cdn.media.ccc.de/congress/2017/34c3-9021-eng-deu-Squeezing_a_key_through_a_carry_bit.en.srt","url":"https://api.media.ccc.de/public/recordings/44474","event_url":"https://api.media.ccc.de/public/events/23d59026-ab98-4f6c-a46d-0bb3e1788a67","conference_url":"https://api.media.ccc.de/public/conferences/34c3"},{"size":231,"length":3001,"mime_type":"video/mp4","language":"eng","filename":"34c3-9021-eng-Squeezing_a_key_through_a_carry_bit.mp4","state":"new","folder":"h264-hd","high_quality":true,"width":1920,"height":1080,"updated_at":"2017-12-28T15:34:31.251+01:00","recording_url":"https://cdn.media.ccc.de/congress/2017/h264-hd/34c3-9021-eng-Squeezing_a_key_through_a_carry_bit.mp4","url":"https://api.media.ccc.de/public/recordings/20947","event_url":"https://api.media.ccc.de/public/events/23d59026-ab98-4f6c-a46d-0bb3e1788a67","conference_url":"https://api.media.ccc.de/public/conferences/34c3"},{"size":232,"length":3001,"mime_type":"video/mp4","language":"deu","filename":"34c3-9021-deu-Squeezing_a_key_through_a_carry_bit.mp4","state":"new","folder":"h264-hd","high_quality":true,"width":1920,"height":1080,"updated_at":"2017-12-28T15:34:40.463+01:00","recording_url":"https://cdn.media.ccc.de/congress/2017/h264-hd/34c3-9021-deu-Squeezing_a_key_through_a_carry_bit.mp4","url":"https://api.media.ccc.de/public/recordings/20948","event_url":"https://api.media.ccc.de/public/events/23d59026-ab98-4f6c-a46d-0bb3e1788a67","conference_url":"https://api.media.ccc.de/public/conferences/34c3"},{"size":491,"length":3001,"mime_type":"video/mp4","language":"eng-deu","filename":"34c3-9021-eng-deu-Squeezing_a_key_through_a_carry_bit_hd.mp4","state":"new","folder":"h264-hd","high_quality":true,"width":1920,"height":1080,"updated_at":"2017-12-28T15:34:55.882+01:00","recording_url":"https://cdn.media.ccc.de/congress/2017/h264-hd/34c3-9021-eng-deu-Squeezing_a_key_through_a_carry_bit_hd.mp4","url":"https://api.media.ccc.de/public/recordings/20949","event_url":"https://api.media.ccc.de/public/events/23d59026-ab98-4f6c-a46d-0bb3e1788a67","conference_url":"https://api.media.ccc.de/public/conferences/34c3"},{"size":173,"length":3001,"mime_type":"video/mp4","language":"eng-deu","filename":"34c3-9021-eng-deu-Squeezing_a_key_through_a_carry_bit_sd.mp4","state":"new","folder":"h264-sd","high_quality":false,"width":720,"height":576,"updated_at":"2017-12-28T16:29:16.931+01:00","recording_url":"https://cdn.media.ccc.de/congress/2017/h264-sd/34c3-9021-eng-deu-Squeezing_a_key_through_a_carry_bit_sd.mp4","url":"https://api.media.ccc.de/public/recordings/20998","event_url":"https://api.media.ccc.de/public/events/23d59026-ab98-4f6c-a46d-0bb3e1788a67","conference_url":"https://api.media.ccc.de/public/conferences/34c3"},{"size":308,"length":3001,"mime_type":"video/mp4","language":"eng-deu","filename":"34c3-9021-eng-deu-Squeezing_a_key_through_a_carry_bit_hd-slides.mp4","state":"new","folder":"slides-h264-hd","high_quality":true,"width":1920,"height":1080,"updated_at":"2017-12-28T16:57:03.393+01:00","recording_url":"https://cdn.media.ccc.de/congress/2017/slides-h264-hd/34c3-9021-eng-deu-Squeezing_a_key_through_a_carry_bit_hd-slides.mp4","url":"https://api.media.ccc.de/public/recordings/21028","event_url":"https://api.media.ccc.de/public/events/23d59026-ab98-4f6c-a46d-0bb3e1788a67","conference_url":"https://api.media.ccc.de/public/conferences/34c3"},{"size":625,"length":3001,"mime_type":"video/webm","language":"eng-deu","filename":"34c3-9021-eng-deu-Squeezing_a_key_through_a_carry_bit_webm-sd.webm","state":"new","folder":"webm-sd","high_quality":false,"width":720,"height":576,"updated_at":"2017-12-28T17:54:29.747+01:00","recording_url":"https://cdn.media.ccc.de/congress/2017/webm-sd/34c3-9021-eng-deu-Squeezing_a_key_through_a_carry_bit_webm-sd.webm","url":"https://api.media.ccc.de/public/recordings/21094","event_url":"https://api.media.ccc.de/public/events/23d59026-ab98-4f6c-a46d-0bb3e1788a67","conference_url":"https://api.media.ccc.de/public/conferences/34c3"},{"size":45,"length":2986,"mime_type":"audio/mpeg","language":"eng","filename":"34c3-9021-eng-Squeezing_a_key_through_a_carry_bit.mp3","state":"new","folder":"mp3","high_quality":false,"width":0,"height":0,"updated_at":"2017-12-28T20:12:12.669+01:00","recording_url":"https://cdn.media.ccc.de/congress/2017/mp3/34c3-9021-eng-Squeezing_a_key_through_a_carry_bit.mp3","url":"https://api.media.ccc.de/public/recordings/21127","event_url":"https://api.media.ccc.de/public/events/23d59026-ab98-4f6c-a46d-0bb3e1788a67","conference_url":"https://api.media.ccc.de/public/conferences/34c3"},{"size":28,"length":2986,"mime_type":"audio/opus","language":"eng","filename":"34c3-9021-eng-Squeezing_a_key_through_a_carry_bit.opus","state":"new","folder":"opus","high_quality":false,"width":0,"height":0,"updated_at":"2017-12-28T20:12:47.695+01:00","recording_url":"https://cdn.media.ccc.de/congress/2017/opus/34c3-9021-eng-Squeezing_a_key_through_a_carry_bit.opus","url":"https://api.media.ccc.de/public/recordings/21128","event_url":"https://api.media.ccc.de/public/events/23d59026-ab98-4f6c-a46d-0bb3e1788a67","conference_url":"https://api.media.ccc.de/public/conferences/34c3"},{"size":446,"length":3001,"mime_type":"video/webm","language":"eng-deu","filename":"34c3-9021-eng-deu-Squeezing_a_key_through_a_carry_bit_webm-hd.webm","state":"new","folder":"webm-hd","high_quality":true,"width":1920,"height":1080,"updated_at":"2017-12-28T21:37:23.531+01:00","recording_url":"https://cdn.media.ccc.de/congress/2017/webm-hd/34c3-9021-eng-deu-Squeezing_a_key_through_a_carry_bit_webm-hd.webm","url":"https://api.media.ccc.de/public/recordings/21242","event_url":"https://api.media.ccc.de/public/events/23d59026-ab98-4f6c-a46d-0bb3e1788a67","conference_url":"https://api.media.ccc.de/public/conferences/34c3"},{"size":64,"length":3001,"mime_type":"video/mp4","language":"eng","filename":"34c3-9021-eng-Squeezing_a_key_through_a_carry_bit_sd-slides.mp4","state":"new","folder":"slides-h264-sd","high_quality":false,"width":720,"height":576,"updated_at":"2018-01-02T15:17:18.967+01:00","recording_url":"https://cdn.media.ccc.de/congress/2017/slides-h264-sd/34c3-9021-eng-Squeezing_a_key_through_a_carry_bit_sd-slides.mp4","url":"https://api.media.ccc.de/public/recordings/22251","event_url":"https://api.media.ccc.de/public/events/23d59026-ab98-4f6c-a46d-0bb3e1788a67","conference_url":"https://api.media.ccc.de/public/conferences/34c3"},{"size":5,"length":null,"mime_type":"application/pdf","language":"eng","filename":"34c3-9021-squeezing_a_key_through_a_carry_bit.pdf","state":"new","folder":"slides-pdf","high_quality":true,"width":null,"height":null,"updated_at":"2018-01-08T18:52:26.582+01:00","recording_url":"https://cdn.media.ccc.de/congress/2017/slides-pdf/34c3-9021-squeezing_a_key_through_a_carry_bit.pdf","url":"https://api.media.ccc.de/public/recordings/22450","event_url":"https://api.media.ccc.de/public/events/23d59026-ab98-4f6c-a46d-0bb3e1788a67","conference_url":"https://api.media.ccc.de/public/conferences/34c3"}]}