Cursive
@cursive_team
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Research & design studio building cryptography for human connection 💫
Joined February 2024
At Devcon SEA, Cursive is thrilled to be curating ✨ Cryptographic Connections ✨, a museum exhibition showcasing the importance of cryptography and its role in advancing human connection. ⬇️
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We're excited to introduce Cursive, a cryptography and design lab building applications of signed data ✍️.
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trigger warning // ✨ math ✨. At @zeroknowledgefm's ZK11, we used FHE to build a private set intersection (PSI) feature, letting attendees find shared activities without revealing extra info. Here's a step-by-step 🧵:
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This past weekend, Cursive gave every attendee at @paradigm Frontiers an NFC badge and built a suite of MPC-powered social cryptography experiences on top. Check out the highlights ⬇️
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At @zeroknowledgefm's ZK Summit 11 in Athens, we provided NFC cards for attendees to gather digital signatures when meeting others or attending talks. On top of these signatures, we built features based on advanced cryptography including ZKPs, 2PC+FHE, and folding schemes.
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Check out @andrewlu_ & @viv_boop's ZK Summit 12 talk for a glimpse into the future of cryptographic connection: It's our first time sharing Trinity, unbreakable consent, narrowcasting, and ✨ digital pheromones ✨. More details ⬇️.
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In collaboration with @zkv_xyz, Cursive will be demoing at ZK Summit 12 next Tuesday! All attendees will receive an NFC card, enabling them to build a private social graph and try out ZK & MPC experiences focused on human connection 🧵
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LFG ✨
Possible futures of the Ethereum protocol, part 6: The Splurge.
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Last week at @EFDevcon, Cursive curated Cryptographic Connections, a museum exhibition highlighting cryptography's role in advancing human connection.
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Signature Singularity Residents ( showing off their Cursive NFC rings. coming soon to more events!
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ZK Summit 12 was an amazing time. Some new MPC games, PSI over cryptographic hot takes, and 5 rings from our newest collection to attendees with 33+ taps!. Let us know if you want Cursive tech in your community or upcoming event!
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We'd like to share some technical & design reflections from our NFC + advanced cryptography activation at @zeroknowledgefm's ZK Summit 11 in Athens. Check it out at
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For those of you attending @zeroknowledgefm ZK Summit 11 today, you’ll get a Cursive NFC card alongside your badge! Tap other attendee badges to share contact information or check into talks.
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Yesterday we generated the first real-world coSNARKs in collaboration with @TACEO_IO and @PrivacyScaling! Today you can try it yourself at the Cursive booth @EFDevcon!.
After months of work on coSNARKs tools, we needed a network to generate the privacy preserving proofs. Together with @cursive_team and @PrivacyScaling, we established the coSNARK alphanet. This morning, the first real-world proofs were generated. Experience it live at @EFDevcon.
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We've been so lucky to be early users of Gauss's phantom-zone, a toolkit to more easily build apps with MP-FHE. Follow their work below and start hacking here!
Today we're opening portal to the Phantom zone. It's a zone parallel to reality where you teleport yourself, take arbitrary actions, but only remember predefined memories when you're back. We build it using multi party fully homomorphic encryption and it's an experiment. But. .
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Our collaboration with @JoinEdgeCity Lanna explored how data ownership and cryptography could be used to build community in a pop-up city. Check out @rachel_aux's reflection on the experience here:
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Day 3 of “Cryptographic Connections” at @EFDevcon. If you haven’t done so already, come stop by and visit the cryptography museum!
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Our first guest post on the blog! @jp4g_ from Mach34 shares his experience implementing folding schemes for our activation at ZK Summit 11 in Athens ⬇️.
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We are thrilled to see under 2020s Ethereum! It's going to be such an exciting decade for Ethereum and cryptography at large.
Going beyond scaling, applications that are built today need to be built with "2020s Ethereum" in mind. Here's what this means:
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We'd like to share a post reflecting on our ETHDenver NFC activation, sharing different cryptography, design, and user behavior learnings!
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For those attending ZK Summit 12 in Lisbon, be sure to check out @viv_boop and @andrewlu_'s talk "Building cryptographic apps for human connection" at 12:30pm on the main stage!.
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Introducing the Cursive blog! We'll be posting technical deep dives, learnings from our activations, and various musings about cryptography at We have two posts to begin with:.
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Private hiring is a new feature where candidates and recruiters could set up profiles for jobs and be privately matched using MPC based on qualifications, interests, and salary expectations. Look for a future blog post to explain the technical details behind private hiring!
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Last chance to check out the cryptography museum exhibitions and claim your NFC chipped merch before @EFDevcon ends!
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We want to shoutout @JoinEdgeCity for connecting us with many of the artists contributing to the exhibition. Finally, we owe a huge thank you to @PrivacyScaling and the @EFDevcon team in making this exhibition a reality. See you in Bangkok! 🇹🇭.
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Last but not least, we built ZK11 Folded, a Spotify Wrapped-like experience where you could generate one Nova folding proof summarizing your entire event experience after it was over.
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Tapping other attendee NFC chips allow you to build your own Devcon social graph and break the ice by discovering common contacts, events, and interests! Those who connect the most through Cursive Connections will receive exclusive NFC chipped goods.
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Finally, our work enables a concept we've been calling called ✨ digital pheromones ✨ -- sending out lightweight, privacy-preserving signals to serendipitously foster connection & coordination. Many more writings coming on this topic. And a live demo in ~1 month 💫
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Our team initially came together from serendipitous invites to Zuzalu! And we've demoed new apps and research at many subsequent pop-up city events. Check out this blog post on Edge City invite stories & apply to Edge City Lanna to hang with our team!.
Have you ever thought about the power of a simple invite?. Big ideas often start with someone saying, "Hey, want to join?”. • 1971, Bill Fernandez, invites Steve Jobs to meet Steve Wozniak at Fernandez's garage. • 1959, Warren Buffett was invited to a dinner party by Dr. Edwin
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We want to give a huge shoutout to @Janmajaya_mall and the rest of the Gauss team for building the MPC/FHE libraries used in this activation. Notably, the private hiring feature was built using Phantom Zone, a new library for multi-party FHE:
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10,000+ people have experienced the products we've built, and we're always open to new ideas and collaborations. Please join our community at shoot us a DM, or email hello@cursive.team!.
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Attendees tapped each other's NFC badges to share contact information and collect a digital signature representing the fact that they met. As a Frontiers special, attendees could see which popular Rust repositories the other person had contributed to. cc @gakonst
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Private Set Intersection (PSI) built using multi-party FHE served as a cryptographic icebreaker, allowing two attendees who had just met to see the contacts they had in common. No information was shared between users except for the people they had both met.
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As a sneak preview, artist @GordonBergerArt has created 6 drawings, each one inspired by a unique emotion he was feeling at the time. You are invited to privately submit the emotion you feel when looking at the art, and check if you both felt the same with a ZKP!
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Upon meeting another attendee, you two could use 2-party computation and fully homomorphic encryption to privately compute the people and talks you had in common. You learned nothing about the other person unless both of you had met the same person or gone to the same talk!
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In the past, we've launched experiences at Zuzalu, Devconnect, and ETHDenver where participants received signatures from NFC cards to digitize in-person interactions. Read more here:.
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We owe a huge thanks to @PrivacyScaling for funding this work, and to Skylar and the @EFDevcon team for giving us the opportunity to showcase cryptography in practice at their amazing event!.
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Cryptographic Connections will feature 3 types of exhibits:.1️⃣ Interactive pieces telling the history of cryptography.2️⃣ Intuitive explainers for cryptographic building blocks including MPC, FHE, and zkEmail.3️⃣ Artist interpretations of the meaning and importance of cryptography
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And of course, we owe a huge thanks to @gakonst, @caitlinxyz, and the rest of the Frontiers team for helping to make this activation happen. It was an exceptional event! check out
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Visitors will receive an NFC chip as their exhibition ticket. This chip is also your gateway into 💫 Cursive Connections 💫 , an app experience where MPC and ZK let you more safely and effectively connect with Devcon attendees by matching on private interests and opportunities.
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We focus on building tangible, accessible, and well-designed applications. We care deeply about educating users on the affordances of cryptography in intuitive ways.
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Finally, be sure to follow Cursive if you're interested in more social cryptography experiences like this. And join the Telegram here:
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Special shoutout to Gauss Labs ( for building 2PC/FHE and Mach34 ( for building folding schemes!.
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Progress in advanced cryptography, especially zero knowledge proofs and fully homomorphic encryption, will supercharge signatures and unlock new opportunities for practical use.
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Trinity enables narrowcasting, the opposite of broadcasting. It enables you to send info to whoever it is most relevant to, instead of public posting in feeds or group chats. We believe this will lead to significantly more efficient human coordination.
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We're excited to share our new directions in the coming months, stay tuned. And learn more about us at 💫.
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Thousands of Devcon attendees experienced exhibits ranging from interactive demos explaining encryption and zkTLS, a live visualization of the anonymized Devcon social graph formed from NFC taps by @micahscopes, and a series of ZK-powered art pieces from @GordonBergerArt!
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As in past activations, we enabled participants to make ZK proofs about their tap signatures to share on Twitter. Participants that proved they met 50+ people received a Cursive NFC ring 💍
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First off, collecting multiple signatures allowed you to generate zero knowledge proofs about your event attendance. For example, you could prove that you met 10 people at ZK Summit without revealing exactly who those people were.
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We believe that digital signatures are key to enabling widespread data ownership and authenticity on the Internet.
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We're sharing a second post about our ETHDenver NFC activation, this one covering data custody preference learnings from an A/B test with 2000 participants.
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Huge thank you @AnnaRRose and @Agni_deneve for all of their support, to @zkv_xyz for the cards + prizes support, and to the whole @zeroknowledgefm team for another high quality event.
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If you want to learn more about how these features were built, you can check out the repo on Github: To learn more about Cursive, visit or join our Telegram:
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Each signature you collected was visualized as a stamp, using a generative art algorithm from @stefan_contiero! These stamps were compiled into a single art piece representing your ETHDenver experience, which will be mintable as an NFT on @ArtBlocksEngine.
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Trinity and similar 2PC schemes enable unbreakable consent -- a mathematical requirement for all parties to consent to a computation before any info is revealed. We believe this is a fundamental shift from AI algorithms and ad markets that use our data however they wish.
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Trinity is a new MPC scheme we researched in house, improving the UX and DevX of consumer 2PC significantly. It combines ideas from Garbled Circuits, KZG Witness Encryption, and PLONK. The high-level setup is at
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Over the course of Devcon, a total of 2000 people registered for the app, tapping more than 17,000 times altogether. Special shoutout to those who built the most expansive Devcon social graphs!
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Come stop by our cryptography museum exhibition at @EFDevcon if you’re interested in art, cryptography, or both!.
👉 Don't miss the @cursive_team museum exhibition at Devcon showing the importance of cryptography & its role in advancing human connection. Grab a Cursive NFC chip near the entrance on Level G to discover & deepen your connections with MPC.
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Tapping someone else's badge allowed you to privately share selected socials & a unique digital signature as a verifiable proof of meeting.
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Huge shoutout to @zkv_xyz for supporting cards + prizes, and @AnnaRRose @Agni_deneve for giving us the opportunity to demo at such a high quality event!.
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Simultaneously, the Cursive Connections app allowed Devcon attendees to connect with others by tapping NFC chips, build a private social graph of the people they met, and discover what they had in common using Private Set Intersection (PSI).
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Each quest required meeting specific users or going to certain locations. Users completed quests by making a ZK proof of satisfying the requirements, maintaining full ownership over their collection of signatures.
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Take a read if you're interested in learning about real-life cryptography deployments, outside the confines of research and blockchain infra!.
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For context, ZK11 attendees were able to collect signatures from NFC cards that represented activities like meeting someone else (alongside contact info) or attending a talk (alongside a description/slides).
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You also may have realized that either A or B could've withheld their decryption share, leading to only one person learning the overlap. This can be resolved with something like @xyz_pierre's
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And we will have longer form blog posts for our ETHDenver learnings coming soon on -- stay tuned! ✨.
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In Round 1, each user creates a shared encryption public key using both of the shares, as well as sending each other a new relinearization key share for later in the computation. This is a mini 2-party computation (2PC).
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If you don't like wearing rings, they also serve as great necklaces when put on a chain 💫.
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This was an order of magnitude larger than our ZuStamps activation at Zuzalu and at @EFDevconnect -- we will continue to bring data ownership and authenticity to more people and events, DM us if you're interested in using this tech!.
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We collaborated with @TACEO_IO so that users could generate collaborative SNARKs of how many people they met at Devcon while keeping their social graph private. You can learn more about how coSNARKs were implemented here:
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You can avoid this by ZK proving you've encrypted a bitvector from valid signatures you have, using a tool like @backaes @PrivacyScaling's This will be included in a later iteration!.
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This PSI cryptography was built by @Janmajaya_mall @backaes using Multi-Party BFV. The above notes from @vivboop reference variables used in a fork of their code at
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And we could have used simpler cryptography to perform PSI, but we wanted to experiment with Multi-Party FHE as a more programmable toolkit for private, multiplayer operations. More coming 🔜.
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PSI was built as an icebreaker, allowing you to connect with other attendees over shared contacts and talks. Crucially, none of your activities were revealed to the other person unless both of you had done it.
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Like ZK Summit 11, this activation is focused on showcasing cutting edge cryptography research from teams like @gauss_labs @tlsnotary & @PrivacyScaling. We have a cohesive app experience brewing for @JoinEdgeCity and @EFDevcon, we'll share more soon 👀.
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In the past few months, we've explored a wider range of MPC tools like garbled circuits, laconic oblivious transfer, and secret sharing. We're excited to share some concrete demos of these techniques for attendees to try!.
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First up is a retrospective on ZuStamps, an experience we built at Zuzalu allowing residents to prove participation in events and unlock unique experiences by tapping NFC badges:
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A and B then compute and send partial decryption shares of this relinearized ciphertext.
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Each user generates a final relinearization key from the shares, which is used to relinearize the multiplication ciphertext. There's more explanation of why this is necessary here:
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At the end of the event, you’ll be able to participate in ZK 11 Folded, where you can generate a Nova folding proof summarizing your entire event experience, just like Spotify Wrapped!.
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In Round 2, each user multiplies the two bitvector ciphertexts homomorphically, which would only leaves a 1 in the indices where both A and B had a 1.
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They each FH encrypt their activity bitvector to the shared encryption key, producing a ciphertext they send each other. As they're encrypted with the same key, we can do FH operations across both!.
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It'll cover Cursive's theses on how cryptography can improve human connection, and an examination of different tech and social trends that suggest our work is critical & timely.
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Thanks for reading this far! Please reach out to learn more, or join our telegram: Now stop being a nerd and go touch some grass.
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Collect signatures to generate zero knowledge proofs about your event experience. You can even privately compute the connections and talks you have in common with a friend using 2PC + FHE!.
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Upon registering for the app, each user generates a public key share and relinearization key share. When PSI starts between A and B, they each download each other's shares.
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We'll conclude with 3 concrete consumer affordances of our techniques, which point towards a future with more serendipity, safety, and ownership of our digital identities 💫.
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The careful observer may have noticed that A or B could lie about their activities, and make a bitvector of all 1s that would reveal the other person's full bitvector upon PSI.
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And if you're not able to attend, don't worry! The talk will be recorded and we'll share it as soon as it's up.
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In Round 3, A and B decrypt their relinearized ciphertext using the shares in another mini 2PC. The resulting bitvector is the overlap of their two activities! From the example above, that would be {0, 0, 1, 0, 0}, which means they both did activity 3.
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We'll also go through the main cryptographic tools we've used in our apps: NFC chips with cryptography, ZK proofs, private set intersection, and multi-party FHE.
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We'll have prizes for the top 3 folks on the tap leaderboard, and 10 lucky attendees with over 25 taps will be randomly selected to get their own Cursive NFC ring 💍.
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We want to highlight the non-interactive protocol, which reduces the rounds of interaction between parties to a single decryption step. This protocol was in part motivated by attempts to make our PSI features more async!.
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Each activity was given a specific index before the event. A and B create bitvectors, placing a 1 in the index of every activity they have a signature for.
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