SEIPDv2.
The OpenPGP v6 encrypted-message packet. SEIPDv2 wraps your ciphertext in authenticated encryption (AEAD, in OCB mode) so that any tampering is detected cryptographically — a cleaner, stronger design than the integrity check bolted onto v4 messages.
SEIPDv2 stands for Symmetrically Encrypted Integrity Protected Data, version 2. It's the packet type that OpenPGP v6 (RFC 9580) uses to carry an encrypted message. It encrypts with a symmetric cipher (AES) in an AEAD mode — specifically OCB — which produces ciphertext and an authentication tag in one operation.
Why AEAD matters.
"AEAD" means Authenticated Encryption with Associated Data. The cipher doesn't just hide the message — it also produces a tag that proves the ciphertext wasn't altered. If even a single byte is flipped in transit, decryption fails loudly instead of returning garbage or, worse, attacker-chosen plaintext.
v4 OpenPGP achieved integrity with a separate MDC packet appended to the message — effective, but a bolt-on. SEIPDv2 makes integrity an intrinsic property of the encryption itself, which is both simpler and harder to get wrong.
PGPony picks the format automatically: SEIPDv2 when every recipient holds a v6 key, classic v4 otherwise — so older contacts keep working without you thinking about it.
sq) and the RFC 9580 Appendix A test
vectors.
Related terms
Get PGPony
Free OpenPGP encryption for iOS and Android. No accounts, no tracking.