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#x3dh

2026-06-19 9 min read explainers

Cryptographic Deniability: Why an Encrypted Message Can't Be Proven in Court

How cryptographic deniability lets an encrypted chat authenticate its participants yet prove nothing to a third party — the OTR origin, Signal's offline deniability, and the legal caveat.

cryptographic-deniability off-the-record double-ratchet x3dh metadata-privacy

2026-06-19 9 min read explainers

Prekey Bundles: How Encrypted Chat Works When You're Offline

How prekey bundles let encrypted chat work when the recipient is offline: what they contain, how a sender derives a shared secret alone, and the key-substitution risk.

prekey-bundle x3dh key-exchange asynchronous-messaging forward-secrecy

2026-06-19 9 min read explainers

X3DH, Explained: The Handshake Behind Asynchronous Encryption

How X3DH lets two people share an encryption key when one is offline — the four Diffie-Hellman operations, what each provides, and the post-quantum upgrade.

x3dh key-exchange forward-secrecy post-quantum double-ratchet