2024-01-19 2026-01-12 Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer 0 Simple S2K 2 No RFC9580, Section 3.7.1.1 1 Salted S2K 10 Only when string is high entropy RFC9580, Section 3.7.1.2 2 Reserved value No 3 Iterated and Salted S2K 11 Yes RFC9580, Section 3.7.1.3 4 Argon2 20 Yes RFC9580, Section 3.7.1.4 5-99 Unassigned 100-110 Private or Experimental Use As appropriate 111-255 Unassigned RFC Required 0 Yes Reserved - this Packet Type ID MUST NOT be used 1 Yes Public Key Encrypted Session Key Packet PKESK RFC9580, Section 5.1 2 Yes Signature Packet SIG RFC9580, Section 5.2 3 Yes Symmetric Key Encrypted Session Key Packet SKESK RFC9580, Section 5.3 4 Yes One-Pass Signature Packet OPS RFC9580, Section 5.4 5 Yes Secret Key Packet SECKEY RFC9580, Section 5.5.1.3 6 Yes Public Key Packet PUBKEY RFC9580, Section 5.5.1.1 7 Yes Secret Subkey Packet SECSUBKEY RFC9580, Section 5.5.1.4 8 Yes Compressed Data Packet COMP RFC9580, Section 5.6 9 Yes Symmetrically Encrypted Data Packet SED RFC9580, Section 5.7 10 Yes Marker Packet MARKER RFC9580, Section 5.8 11 Yes Literal Data Packet LIT RFC9580, Section 5.9 12 Yes Trust Packet TRUST RFC9580, Section 5.10 13 Yes User ID Packet UID RFC9580, Section 5.11 14 Yes Public Subkey Packet PUBSUBKEY RFC9580, Section 5.5.1.2 15-16 Unassigned 17 Yes User Attribute Packet UAT RFC9580, Section 5.12 18 Yes Symmetrically Encrypted and Integrity Protected Data Packet SEIPD RFC9580, Section 5.13 19 Yes Reserved (formerly Modification Detection Code Packet) RFC9580, Section 5.13.1 20 Yes Reserved 21 Yes Padding Packet PADDING RFC9580, Section 5.14 22-39 Yes Unassigned Critical Packets 40-59 No Unassigned Non-Critical Packets 60-63 No Private or Experimental Use Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer 0 Reserved 1 Image Attribute Subpacket RFC9580, Section 5.12.1 2-99 Unassigned 100-110 Private or Experimental Use 111-255 Unassigned Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer 0 Reserved 1 JPEG JFIF 2-99 Unassigned 100-110 Private or Experimental Use 111-255 Unassigned Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer 0 Reserved 1 Reserved 2 Signature Creation Time RFC9580, Section 5.2.3.11 3 Signature Expiration Time RFC9580, Section 5.2.3.18 4 Exportable Certification RFC9580, Section 5.2.3.19 5 Trust Signature RFC9580, Section 5.2.3.21 6 Regular Expression RFC9580, Section 5.2.3.22 7 Revocable RFC9580, Section 5.2.3.20 8 Reserved 9 Key Expiration Time RFC9580, Section 5.2.3.13 10 Placeholder for backward compatibility 11 Preferred Symmetric Ciphers for v1 SEIPD RFC9580, Section 5.2.3.14 12 Revocation Key (deprecated) RFC9580, Section 5.2.3.23 13-15 Reserved 16 Issuer Key ID RFC9580, Section 5.2.3.12 17-19 Reserved 20 Notation Data RFC9580, Section 5.2.3.24 21 Preferred Hash Algorithms RFC9580, Section 5.2.3.16 22 Preferred Compression Algorithms RFC9580, Section 5.2.3.17 23 Key Server Preferences RFC9580, Section 5.2.3.25 24 Preferred Key Server RFC9580, Section 5.2.3.26 25 Primary User ID RFC9580, Section 5.2.3.27 26 Policy URI RFC9580, Section 5.2.3.28 27 Key Flags RFC9580, Section 5.2.3.29 28 Signer's User ID RFC9580, Section 5.2.3.30 29 Reason for Revocation RFC9580, Section 5.2.3.31 30 Features RFC9580, Section 5.2.3.32 31 Signature Target RFC9580, Section 5.2.3.33 32 Embedded Signature RFC9580, Section 5.2.3.34 33 Issuer Fingerprint RFC9580, Section 5.2.3.35 34 Reserved 35 Intended Recipient Fingerprint RFC9580, Section 5.2.3.36 37 Reserved (Attested Certifications) 38 Reserved (Key Block) 39 Preferred AEAD Ciphersuites RFC9580, Section 5.2.3.15 40-99 Unassigned 100-110 Private or Experimental Use 111-127 Unassigned Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer This is a variable length bit field. 0x80... No-modify The keyholder requests that this key only be modified or updated by the keyholder or an administrator of the key server. Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer 0 No reason specified (Key Revocation or Certification Revocation signatures) 1 Key is superseded (Key Revocation signatures) 2 Key material has been compromised (Key Revocation signatures) 3 Key is retired and no longer used (Key Revocation signatures) 4-31 Unassigned 32 User ID information is no longer valid (Certification Revocation signatures) 33-99 Unassigned 100-110 Private Use Specification Required This is a variable length bit field. Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer 0x01... Version 1 Symmetrically Encrypted and Integrity Protected Data packet RFC9580, Section 5.13.1 0x02... Reserved 0x04... Reserved 0x08... Version 2 Symmetrically Encrypted and Integrity Protected Data packet RFC9580, Section 5.13.2 Registry closed Those wishing to use the removed "New Packet Versions" registry should instead register new versions of the relevant packets in the "OpenPGP Key and Signature Versions", "OpenPGP Key IDs and Fingerprints", and "OpenPGP Encrypted Message Packet Versions" registries. Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer This is a variable length bit field. 0x01... This key may be used to make User ID certifications (Signature Type IDs 0x10-0x13) or Direct Key signatures (Signature Type ID 0x1F) over other keys. 0x02... This key may be used to sign data. 0x04... This key may be used to encrypt communications. 0x08... This key may be used to encrypt storage. 0x10... The private component of this key may have been split by a secret-sharing mechanism. 0x20... This key may be used for authentication. 0x80... The private component of this key may be in the possession of more than one person. 0x0004... Reserved (ADSK) 0x0008... Reserved (timestamping) Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer The field specifications enclosed in square brackets for PKESK Format represent fields that may or may not be present, depending on the PKESK version. 0 Reserved 1 RSA (Encrypt or Sign) FIPS186 MPI(n), MPI(e) RFC9580, Section 5.5.5.1 MPI(d), MPI(p), MPI(q), MPI(u) MPI(m^d mod n) RFC9580, Section 5.2.3.1 MPI(m^e mod n) RFC9580, Section 5.1.3 2 RSA Encrypt-Only FIPS186 MPI(n), MPI(e) RFC9580, Section 5.5.5.1 MPI(d), MPI(p), MPI(q), MPI(u) N/A MPI(m^e mod n) RFC9580, Section 5.1.3 3 RSA Sign-Only FIPS186 MPI(n), MPI(e) RFC9580, Section 5.5.5.1 MPI(d), MPI(p), MPI(q), MPI(u) MPI(m^d mod n) RFC9580, Section 5.2.3.1 N/A 4-15 Unassigned 16 Elgamal (Encrypt-Only) ELGAMAL MPI(p), MPI(g), MPI(y) RFC9580, Section 5.5.5.3 MPI(x) N/A MPI(g^k mod p), MPI(m * y^k mod p) RFC9580, Section 5.1.4 17 DSA (Digital Signature Algorithm) FIPS186 MPI(p), MPI(q), MPI(g), MPI(y) RFC9580, Section 5.5.5.2 MPI(x) MPI(r), MPI(s) RFC9580, Section 5.2.3.2 N/A 18 ECDH public key algorithm OID, MPI(point in curve-specific point format), KDFParams RFC9580, Sections 9.2.1 and 5.5.5.6 MPI(value in curve-specific format) RFC9580, Section 9.2.1 N/A MPI(point in curve-specific point format), size octet, encoded key RFC9580, Sections 9.2.1, 5.1.5, and 11.5 19 ECDSA public key algorithm FIPS186 OID, MPI(point in SEC1 format) RFC9580, Section 5.5.5.4 MPI(value) MPI(r), MPI(s) RFC9580, Section 5.2.3.2 N/A 20 Reserved (formerly Elgamal Encrypt or Sign) 21 Reserved for Diffie-Hellman (X9.42, as defined for IETF-S/MIME) 22 EdDSALegacy (deprecated) OID, MPI(point in prefixed native format) RFC9580, Sections 11.2.2 and 5.5.5.5 MPI(value in curve-specific format) RFC9580, Section 9.2.1 MPI, MPI RFC9580, Sections 9.2.1 and 5.2.3.3 N/A 23 Reserved (AEDH) 24 Reserved (AEDSA) 25 X25519 32 octets RFC9580, Section 5.5.5.7 32 octets N/A 32 octets, size octet, encoded key RFC9580, Section 5.1.6 26 X448 56 octets RFC9580, Section 5.5.5.8 56 octets N/A 56 octets, size octet, encoded key RFC9580, Section 5.1.7 27 Ed25519 32 octets RFC9580, Section 5.5.5.9 32 octets 64 octets RFC9580, Section 5.2.3.4 28 Ed448 57 octets RFC9580, Section 5.5.5.10 57 octets 114 octets RFC9580, Section 5.2.3.5 29 Unassigned 30 ML-DSA-65+Ed25519 32 octets Ed25519 public key (Table 6), 1952 octets ML-DSA-65 public key (Table 7) 32 octets Ed25519 secret key (Table 6), 32 octets ML-DSA-65 secret key (Table 7) 64 octets Ed25519 signature (Table 6), 3309 octets ML-DSA-65 signature (Table 7) N/A 31 ML-DSA-87+Ed448 57 octets Ed448 public key (Table 6), 2592 octets ML-DSA-87 public key (Table 7) 57 octets Ed448 secret key (Table 6), 32 octets ML-DSA-87 secret key (Table 7) 114 octets Ed448 signature (Table 6), 4627 octets ML-DSA-87 signature (Table 7) N/A 32 SLH-DSA-SHAKE-128s 32 octets public key (Table 8) 64 octets secret key (Table 8) 7856 octets signature (Table 8) N/A 33 SLH-DSA-SHAKE-128f 32 octets public key (Table 8) 64 octets secret key (Table 8) 17088 octets signature (Table 8) N/A 34 SLH-DSA-SHAKE-256s 64 octets public key (Table 8) 128 octets secret key (Table 8) 29792 octets signature (Table 8) N/A 35 ML-KEM-768+X25519 32 octets X25519 public key (Table 3), 1184 octets ML-KEM-768 public key (Table 4) 32 octets X25519 secret key (Table 3), 64 octets ML-KEM-768 secret key (Table 4) N/A 32 octets X25519 ciphertext, 1088 octets ML-KEM-768 ciphertext, 1 octet remaining length, [1 octet algorithm ID in case of v3 PKESK,] n octets wrapped session key 36 ML-KEM-1024+X448 56 octets X448 public key (Table 3), 1568 octets ML-KEM-1024 public key (Table 4) 56 octets X448 secret key (Table 3), 64 octets ML-KEM-1024 secret key (Table 4) N/A 56 octets X448 ciphertext, 1568 octets ML-KEM-1024 ciphertext, 1 octet remaining length, [1 octet algorithm ID in case of v3 PKESK,] n octets wrapped session key 37-99 Unassigned 100-110 Private or Experimental Use 111-255 Unassigned Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer When registering a new symmetric cipher with a block size of 64 or 128 bits and a key size that is a multiple of 64 bits, no new considerations are needed. If the new cipher has a different block size, there needs to be additional documentation describing how to use the cipher in CFB mode. If the new cipher has an unusual key size, then padding needs to be considered for X25519 and X448 key wrapping, which currently needs no padding. 0 Plaintext or unencrypted data 1 IDEA IDEA 2 TripleDES (or DES-EDE) SP800-67 with 168-bit key derived from 192 3 CAST5 with 128-bit key 4 Blowfish with 128-bit key, 16 rounds BLOWFISH 5 Reserved 6 Reserved 7 AES with 128-bit key AES 8 AES with 192-bit key 9 AES with 256-bit key 10 Twofish with 256-bit key TWOFISH 11 Camellia with 128-bit key 12 Camellia with 192-bit key 13 Camellia with 256-bit key 14-99 Unassigned 100-110 Private or Experimental Use 111-252 Unassigned 253-255 Reserved to avoid collision with Secret Key Encryption (see the OpenPGP Secret Key Encryption (S2K Usage Octet) registry and RFC9580, Section 5.5.3) Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer When registering a new hash algorithm, if the algorithm is also to be used with RSA signing schemes, it must also have an entry in the "OpenPGP Hash Algorithm Identifiers for RSA Signatures' use of EMSA-PKCS1-v1_5 Padding" registry. 0 Reserved 1 MD5 "MD5" N/A 2 SHA-1 FIPS180 "SHA1" N/A 3 RIPEMD-160 RIPEMD-160 "RIPEMD160" N/A 4-7 Reserved 8 SHA2-256 FIPS180 "SHA256" 16 9 SHA2-384 FIPS180 "SHA384" 24 10 SHA2-512 FIPS180 "SHA512" 32 11 SHA2-224 FIPS180 "SHA224" 16 12 SHA3-256 FIPS202 "SHA3-256" 16 13 Reserved 14 SHA3-512 FIPS202 "SHA3-512" 32 15-99 Unassigned 100-110 Private or Experimental Use 111-255 Unassigned Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer 0 Uncompressed 1 ZIP 2 ZLIB 3 BZip2 BZ2 4-99 Unassigned 100-110 Private or Experimental Use 111-255 Unassigned Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer 0 Unprotected - v3 or v4 keys: [cleartext secrets || check(secrets)] v6 keys: [cleartext secrets] Yes Known symmetric cipher algo ID (see RFC9580, Section 9.3) LegacyCFB IV CFB(MD5(passphrase), secrets || check(secrets)) No 253 AEAD params-length (v6-only), cipher-algo, AEAD-mode, S2K-specifier-length (v6-only), S2K-specifier, nonce AEAD(HKDF(S2K(passphrase), info), secrets, packetprefix) Yes 254 CFB params-length (v6-only), cipher-algo, S2K-specifier-length (v6-only), S2K-specifier, IV CFB(S2K(passphrase), secrets || SHA1(secrets)) Yes 255 MalleableCFB cipher-algo, S2K-specifier, IV CFB(S2K(passphrase), secrets || check(secrets)) No Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer 0x00 Binary Signature RFC9580, Section 5.2.1.1 0x01 Text Signature RFC9580, Section 5.2.1.2 0x02 Standalone Signature RFC9580, Section 5.2.1.3 0x03-0x0F Unassigned 0x10 Generic Certification Signature RFC9580, Section 5.2.1.4 0x11 Persona Certification Signature RFC9580, Section 5.2.1.5 0x12 Casual Certification Signature RFC9580, Section 5.2.1.6 0x13 Positive Certification Signature RFC9580, Section 5.2.1.7 0x14-0x17 Unassigned 0x18 Subkey Binding Signature RFC9580, Section 5.2.1.8 0x19 Primary Key Binding Signature RFC9580, Section 5.2.1.9 0x1A-0x1E Unassigned 0x1F Direct Key Signature RFC9580, Section 5.2.1.10 0x20 Key Revocation Signature RFC9580, Section 5.2.1.11 0x21-0x27 Unassigned 0x28 Subkey Revocation Signature RFC9580, Section 5.2.1.12 0x29-0x2F Unassigned 0x30 Certification Revocation Signature RFC9580, Section 5.2.1.13 0x31-0x3F Unassigned 0x40 Timestamp Signature RFC9580, Section 5.2.1.14 0x41-0x4F Unassigned 0x50 Third-Party Confirmation Signature RFC9580, Section 5.2.1.15 0x51-0xFE Unassigned 0xFF Reserved RFC9580, Section 5.2.1.16 Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer 0x80000000 (first bit of the first octet) human-readable Notation value is UTF-8 text Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer Notation names are arbitrary Unicode strings encoded in UTF-8. They reside in two namespaces: the IETF namespace and the user namespace. This registry documents the IETF namespace. The names in this registry MUST NOT contain the "@" character (0x40), since the presence of that character indicates the user namespace. RFC Required When a new key version is defined, the "OpenPGP Key and Signature Versions" registry should also be updated. 3 MD5(MPIs without length octets) 128 low 64 bits of RSA modulus RFC9580, Section 5.5.4.1 4 SHA1(normalized pubkey packet) 160 last 64 bits of fingerprint RFC9580, Section 5.5.4.2 6 SHA256(normalized pubkey packet) 256 first 64 bits of fingerprint RFC9580, Section 5.5.4.3 Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer 1 RFC9580, Section 5.12.1 Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer BEGIN PGP MESSAGE Used for signed, encrypted, or compressed files. BEGIN PGP PUBLIC KEY BLOCK Used for armoring public keys. BEGIN PGP PRIVATE KEY BLOCK Used for armoring private keys. BEGIN PGP SIGNATURE Used for detached signatures, OpenPGP/MIME signatures, and cleartext signatures. Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer Version Implementation information RFC9580, Section 6.2.2.1 Comment Arbitrary text RFC9580, Section 6.2.2.2 Hash Hash algorithms used in some v4 cleartext signed messages RFC9580, Section 6.2.2.3 Charset Character set RFC9580, Section 6.2.2.4 Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer When a new elliptic curve is registered for use with OpenPGP, it should also be added to the "OpenPGP ECC Curve-specific Wire Formats" registry. If it is used for ECDH, also add it to the "OpenPGP ECDH KDF and KEK Parameters" registry. 1.2.840.10045.3.1.7 8 2A 86 48 CE 3D 03 01 07 NIST P-256 ECDSA, ECDH 32 1.3.132.0.34 5 2B 81 04 00 22 NIST P-384 ECDSA, ECDH 48 1.3.132.0.35 5 2B 81 04 00 23 NIST P-521 ECDSA, ECDH 66 1.3.36.3.3.2.8.1.1.7 9 2B 24 03 03 02 08 01 01 07 brainpoolP256r1 ECDSA, ECDH 32 1.3.36.3.3.2.8.1.1.11 9 2B 24 03 03 02 08 01 01 0B brainpoolP384r1 ECDSA, ECDH 48 1.3.36.3.3.2.8.1.1.13 9 2B 24 03 03 02 08 01 01 0D brainpoolP512r1 ECDSA, ECDH 64 1.3.6.1.4.1.11591.15.1 9 2B 06 01 04 01 DA 47 0F 01 Ed25519Legacy EdDSALegacy 32 1.3.6.1.4.1.3029.1.5.1 10 2B 06 01 04 01 97 55 01 05 01 Curve25519Legacy ECDH 32 Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer NIST P-256 SEC1 integer N/A N/A N/A NIST P-384 SEC1 integer N/A N/A N/A NIST P-521 SEC1 integer N/A N/A N/A brainpoolP256r1 SEC1 integer N/A N/A N/A brainpoolP384r1 SEC1 integer N/A N/A N/A brainpoolP512r1 SEC1 integer N/A N/A N/A Ed25519Legacy N/A N/A 32 octets of secret 32 octets of R 32 octets of S Curve25519Legacy prefixed native integer RFC9580, Section 5.5.5.6.1.1 N/A N/A N/A Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer MD5 1.2.840.113549.2.5 0x30, 0x20, 0x30, 0x0C, 0x06, 0x08, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x02, 0x05, 0x05, 0x00, 0x04, 0x10 SHA-1 1.3.14.3.2.26 0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2B, 0x0E, 0x03, 0x02, 0x1A, 0x05, 0x00, 0x04, 0x14 RIPEMD-160 1.3.36.3.2.1 0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2B, 0x24, 0x03, 0x02, 0x01, 0x05, 0x00, 0x04, 0x14 SHA2-256 2.16.840.1.101.3.4.2.1 0x30, 0x31, 0x30, 0x0D, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05, 0x00, 0x04, 0x20 SHA2-384 2.16.840.1.101.3.4.2.2 0x30, 0x41, 0x30, 0x0D, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02, 0x05, 0x00, 0x04, 0x30 SHA2-512 2.16.840.1.101.3.4.2.3 0x30, 0x51, 0x30, 0x0D, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, 0x05, 0x00, 0x04, 0x40 SHA2-224 2.16.840.1.101.3.4.2.4 0x30, 0x2D, 0x30, 0x0D, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04, 0x05, 0x00, 0x04, 0x1C SHA3-256 2.16.840.1.101.3.4.2.8 0x30, 0x31, 0x30, 0x0D, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x08, 0x05, 0x00, 0x04, 0x20 SHA3-512 2.16.840.1.101.3.4.2.10 0x30, 0x51, 0x30, 0x0D, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x0a, 0x05, 0x00, 0x04, 0x40 Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer 0 Reserved 1 EAX EAX 16 16 2 OCB 15 16 3 GCM SP800-38D 12 16 4-99 Unassigned 100-110 Private or Experimental Use 111-255 Unassigned RFC Required When a new version of SEIPD, PKESK, or SKESK are defined, consider also adding a corresponding flag to the "OpenPGP Features Flags" registry. SED RFC9580, Section 5.7 - v2 PKESK No SED RFC9580, Section 5.7 v4 SKESK RFC9580, Section 5.3.1 v3 PKESK RFC9580, Section 5.1.1 No v1 SEIPD RFC9580, Section 5.13.1 v4 SKESK RFC9580, Section 5.3.1 v3 PKESK RFC9580, Section 5.1.1 Yes v2 SEIPD RFC9580, Section 5.13.2 v6 SKESK RFC9580, Section 5.3.2 v6 PKESK RFC9580, Section 5.1.2 Yes RFC Required When a new key version is defined, the "OpenPGP Key IDs and Fingerprints" registry should also be updated. 3 RFC9580, Section 5.5.2.1 3 RFC9580, Section 5.2.2 3 RFC9580, Section 5.4 No 4 RFC9580, Section 5.5.2.2 3 RFC9580, Section 5.2.2 3 RFC9580, Section 5.4 No 4 RFC9580, Section 5.5.2.2 4 RFC9580, Section 5.2.3 3 RFC9580, Section 5.4 Yes 6 RFC9580, Section 5.5.2.3 6 RFC9580, Section 5.2.3 6 RFC9580, Section 5.4 Yes Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer SEC1 0x04 || x || y RFC9580, Section 11.2.1 Prefixed native 0x40 || native RFC9580, Section 11.2.2 Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer integer An integer encoded in big-endian format as a standard OpenPGP MPI RFC9580, Section 3.2 octet string An octet string of fixed length that may be shorter on the wire due to leading zeros being stripped by the MPI encoding and may need to be zero-padded before use RFC9580, Section 11.3.1 prefixed N octets An octet string of fixed length N, prefixed with octet 0x40 to ensure no leading zero octet RFC9580, Section 11.3.2 Specification Required Daniel Kahn Gillmor, Andrew Gallagher, Heiko Schäfer NIST P-256 SHA2-256 AES-128 NIST P-384 SHA2-384 AES-192 NIST P-521 SHA2-512 AES-256 brainpoolP256r1 SHA2-256 AES-128 brainpoolP384r1 SHA2-384 AES-192 brainpoolP512r1 SHA2-512 AES-256 Curve25519Legacy SHA2-256 AES-128