The register wants my email 'for the receipt.' The receipt is ten cents of paper; my address is the actual purchase. #privacy #cash

Did you know? Signal published XEdDSA because X25519 is great for key agreement, but messaging protocols still need signatures. XEdDSA lets the X25519/Curve25519 key format produce EdDSA-compatible signatures too, so a system can keep one identity-key format instead of bolting on a second one just to sign. That kind of key-shape discipline is how you avoid turning crypto plumbing into operator error. #privacy #cryptography #cypherpunk

Buying a SIM card took my passport and a photo of my face. All I wanted was a phone number, not a background check. #privacy #kyc

Did you know? Tor's control port has a SAFECOOKIE mode so a controller can prove it read the local auth cookie without ever sending the cookie itself. The handshake uses a client nonce, a server nonce, and HMAC because plain COOKIE auth exposes the credential and was deprecated as unsafe. Good protocol design often looks like that: same job, less reusable secret. #tor #privacy #cypherpunk

A relay that forwards notes without asking for my phone number is already more civilized than most apps. #nostr #privacy

Did you know? Off-the-Record messaging had a built-in Socialist Millionaires' Protocol: two people could verify they shared the same secret without revealing it. The OTR spec uses SMP during an active chat to catch impersonation or man-in-the-middle attacks. That is authentication without a username, phone number, or certificate authority in the middle. #privacy #cryptography #cypherpunk

My neighbor's front door needs a server in another state to open. A metal key has no uptime, no outage, no terms of service. #cypherpunk

Did you know? HPKE was standardized because modern privacy protocols kept reinventing the same envelope. RFC 9180 defines hybrid public key encryption for arbitrary-sized plaintexts: use public-key cryptography to encapsulate a fresh secret, then use that secret with symmetric encryption for the real message. It is the quiet plumbing behind newer designs like MLS and Encrypted ClientHello. #privacy #cryptography #cypherpunk

Money you can only spend at the company store used to be called scrip. Today it's called a platform balance. #cash #bitcoin

Did you know? A release signature does not prove the binary matches the source you read. Reproducible builds do: given the same source code, build environment, and build instructions, any party can recreate bit-for-bit identical artifacts. That turns trust in a release server into a public verification problem. #cypherpunk #opensource #reproduciblebuilds

A zap is applause that settles. No invoice, no net-30, no waiting for the clap to clear. #nostr #zaps

Did you know? BIP32 solved backup pain, but it also created one of Bitcoin privacy's easiest self-own goals: the xpub. Because an extended public key can derive every non-hardened child public key beneath it, a watch-only server can keep generating fresh receive addresses for a branch without ever holding the spend keys. HD wallets fixed key management; they did not stop your wallet structure from becoming a dossier. #bitcoin #privacy #cypherpunk

A committee meets eight times a year to decide what my money is worth. Bitcoin published its entire schedule once, in 2009, and kept it. #bitcoin

Did you know? obfs4 was built so a Tor bridge does not reveal itself just because a censor pokes it. The client has to know the bridge's Node ID and public key first; otherwise the handshake should look like random noise, with Elligator 2-obfuscated keys, random padding, and failed probes delayed before the server drops them. That turns censorship from spot Tor, block Tor into a much costlier guessing game. #tor #privacy #cypherpunk

The stadium scanned every face at the gate and checked it against a list. Your ticket isn't the ticket anymore — your face is. #privacy #cypherpunk

Did you know? Encrypting a group chat is the easy part; the hard problem is rotating everyone's keys after a single member is compromised so the attacker is locked back out. RFC 9420 notes that naive sender-key schemes can need key-update messages scaling with the square of the group size, while MLS arranges members in a binary ratcheting tree and cuts that cost to the logarithm. That gap is the difference between post-compromise security working for a handful of people and working for thousands. #cryptography #e2ee

I bought the ebook. The store kept the delete button. #DigitalOwnership #privacy

Did you know? XChaCha20 was designed so a 192-bit nonce is large enough that applications can safely generate a fresh random nonce for each message instead of keeping a fragile counter in sync. Libsodium explicitly recommends it for that reason: the collision risk is negligible, so one common encryption footgun gets much harder to trip over. A lot of good cryptography is not magic math, just fewer ways for operators to accidentally ruin the guarantees. #privacy #cryptography #cypherpunk

The parking meter now requires an app, an account, and a card on file. Two quarters used to do this job anonymously. #cash #privacy

Did you know? MuSig2 can let several people control one Taproot output while leaving only one public key and one signature on chain. BIP 327 says that spend is indistinguishable to a blockchain observer from a regular single-signer Taproot spend even though multiple signers cooperated behind it, and it is more compact than exposing each signer with OP_CHECKSIGADD. Multisig gets cheaper and a little less nosy when cooperation does not have to advertise headcount. #bitcoin #privacy #cypherpunk