Hybrid Public Key Encryption (HPKE)

Created
2021-11-16
Last Updated
2025-09-18
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Registries Included Below

HPKE KEM Identifiers

Registration Procedure(s)
Specification Required
Expert(s)
Christopher Wood, Richard Barnes
Reference
[RFC9180]
Request an Assignment
[https://www.iana.org/form/protocol-assignment]
Available Formats

CSV
Value KEM Nsecret Nenc Npk Nsk Auth Reference
0x0000 Reserved N/A N/A N/A N/A yes [RFC9180]
0x0001-0x000F Unassigned
0x0010 DHKEM(P-256, HKDF-SHA256) 32 65 65 32 yes [NISTCurves][RFC5869]
0x0011 DHKEM(P-384, HKDF-SHA384) 48 97 97 48 yes [NISTCurves][RFC5869]
0x0012 DHKEM(P-521, HKDF-SHA512) 64 133 133 66 yes [NISTCurves][RFC5869]
0x0013 DHKEM(CP-256, HKDF-SHA256) 32 32 32 32 Yes [NISTCurves][RFC6090][draft-irtf-cfrg-dnhpke-01]
0x0014 DHKEM(CP-384, HKDF-SHA384) 48 48 48 48 Yes [NISTCurves][RFC6090][draft-irtf-cfrg-dnhpke-01]
0x0015 DHKEM(CP-521, HKDF-SHA512) 64 66 66 66 Yes [NISTCurves][RFC6090][draft-irtf-cfrg-dnhpke-01]
0x0016 DHKEM(secp256k1, HKDF-SHA256) 32 65 65 32 yes [Standards for Efficient Cryptography 2 (SEC 2)][draft-wahby-cfrg-hpke-kem-secp256k1-01]
0x0017-0x001F Unassigned
0x0020 DHKEM(X25519, HKDF-SHA256) 32 32 32 32 yes [RFC5869][RFC7748]
0x0021 DHKEM(X448, HKDF-SHA512) 64 56 56 56 yes [RFC5869][RFC7748]
0x0022 DHKEM(X25519+Elligator, HKDF-SHA256) 32 32 32 32 yes [https://lsd.gnunet.org/lsd0011/][draft-schanzen-hpke-elligator-kem-01]
0x0023-0x002F Unassigned
0x0030 X25519Kyber768Draft00 64 1120 1216 2432 no [draft-westerbaan-cfrg-hpke-xyber768d00-02]
0x0031-0x0039 Unassigned
0x0040 ML-KEM-512 32 768 800 64 no [draft-connolly-cfrg-hpke-mlkem-04]
0x0041 ML-KEM-768 32 1088 1184 64 no [draft-connolly-cfrg-hpke-mlkem-04]
0x0042 ML-KEM-1024 32 1568 1568 64 no [draft-connolly-cfrg-hpke-mlkem-04]
0x0043-0x6479 Unassigned
0x647a X-Wing 32 1120 1216 32 no [draft-connolly-cfrg-xwing-kem-06]
0x647b-0xFFFF Unassigned

HPKE KDF Identifiers

Registration Procedure(s)
Specification Required
Expert(s)
Christopher Wood, Richard Barnes
Reference
[RFC9180]
Request an Assignment
[https://www.iana.org/form/protocol-assignment]
Available Formats

CSV
Value KDF Nh Reference
0x0000 Reserved N/A [RFC9180]
0x0001 HKDF-SHA256 32 [RFC5869]
0x0002 HKDF-SHA384 48 [RFC5869]
0x0003 HKDF-SHA512 64 [RFC5869]
0x0004-0xFFFF Unassigned

HPKE AEAD Identifiers

Registration Procedure(s)
Specification Required
Expert(s)
Christopher Wood, Richard Barnes
Reference
[RFC9180]
Request an Assignment
[https://www.iana.org/form/protocol-assignment]
Available Formats

CSV
Value AEAD Nk Nn Nt Reference
0x0000 Reserved N/A N/A N/A [RFC9180]
0x0001 AES-128-GCM 16 12 16 [GCM]
0x0002 AES-256-GCM 32 12 16 [GCM]
0x0003 ChaCha20Poly1305 32 12 16 [RFC8439]
0x0004-0xFFFE Unassigned
0xFFFF Export-only N/A N/A N/A [RFC9180]