Post #3983290
2026-07-21 10:18 UTC
@greyarea@mitra.vpclmulqdq.moe I added HPKE algorithm parameters to the FEP:
https://codeberg.org/silverpill/feps/src/branch/main/0806/fep-0806.md#algorithms
KEM: DHKEM(X25519, HKDF-SHA256)
AEAD: ChaCha20Poly1305
KDF: HKDF-SHA256
"info" string: fep-0806-info
"aad" string: fep-0806-aad
Does it look right?
KEM/AEAD/KDF choices are not my preferences, I just copied them from another HPKE+ed25519 implementation.
Replies (1)
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@greyarea@mitra.vpclmulqdq.moe 2026-07-21 13:58
@silverpill@mitra.social The primitive choices are sensible. The "aad" is sent in the clear (or just public as it is now) so you could do something like "fep-0806-aad" | ':' | | ':' | |':' | . If the proof covers all of that then it's not strictly needed, but it's cheap paranoia. I was going to say add version info to the labels, but fep0806:cipherAlgorithm covers that.