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Posted on Originally published at z-text.org

Disposable Private Messaging Without a Phone Number: How Z-Text's Crypto-Erase Actually Works

#cryptography #security #privacy #blockchain

A burner phone protects you only while you execute it perfectly. Z-Text's approach is different: the protection is built into the code, not dependent on your discipline.

The core mechanism

Z-Text lets you create a disposable messaging identity for $3 — no phone number, SIM, or email. Here's what's actually happening under the hood:

  • Local encryption: message database and wallet are each encrypted separately, with their own 32 random bytes stored in the platform keystore — not derived from a seed, not guessable.
  • The wipe: the panic PIN destroys both keys, then verifies the deletion happened. What's left on flash: encrypted blocks with no key anywhere to open them. Same principle as full-disk encryption on any modern phone — crypto-erase, not overwrite.
  • The transport: messages are AES-256-GCM encrypted on-device, then delivered as BitcoinZ shielded transactions (Sapling-family zk-SNARKs), hiding sender, recipient, and amount on-chain.

The identity/content distinction

This is the part worth understanding precisely: wiping an identity destroys the key, not the message. Z-Text never deletes anything from the blockchain — what's sent stays there permanently, shielded.

If both parties in a conversation eventually wipe their keys, with no backup anywhere, the message doesn't disappear. It becomes permanently unreadable — by anyone, including Z-Text. Not through deletion. Through the simple fact that nothing exists anymore that can decrypt it.

What it isn't

Worth being precise about limits:

  • A disposable identity on your daily phone still shares that device's IP and network fingerprint with your primary identity
  • No independent security audit yet — there's a live, funded bug bounty (7 ZEC, with a verified on-chain payout already on record: t1bV6TkNwWBGBPtGhJCNEQZChpGVivHhHGE), which is a real signal, not a substitute for a formal audit
  • Text-only by design — no files, images, or voice

Why now

India just mandated SIM-binding for WhatsApp, Telegram, Signal, and Snapchat — apps must reverify the physical SIM is present continuously, not just at registration. The FCC has an open proposal (Docket 17-59/02-278) requiring government ID before activating a phone line, opposed in writing by EPIC and CDT. Phone-number-bound identity is becoming a structural liability in more than one jurisdiction at once.

Z-Text sits outside that perimeter — built on a blockchain shielded by zk-SNARKs, not a phone number.

Currently in private beta. Full writeup: https://z-text.org/disposable-private-messaging-no-phone-number/

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