Public Key Announcement

A Public Key Announcement is a way to note a new cryptographic key that can be used in DSNP to secure and verify the authenticity of communications.

The most recently published key (if one exists) for a given key type should be treated as the active key of that key type.


FieldDescriptionData TypeSerializationParquet TypeBloom Filter
announcementTypeAnnouncement Type Enum (7)enumdecimalINT32no
fromIdid of the user creating the Announcement64 bit unsigned integerdecimalUINT_64YES
keyTypeKey Type EnumenumdecimalINT32YES
keyIduser-assigned identifier64 bit unsigned integerdecimalUINT_64no
publicKeypublic key in multikey formatvariable length byte arrayUTF-8BYTE_ARRAYno

Field Requirements


  • MUST be fixed to 7



  • MUST be an allowed Key Type value

Allowed Key Types

ValueNameAllowed Algorithms (multicodec)Purpose
1keyAgreementx25519-pubA Curve25519 public key that can be used in key exchange protocols to generate a shared secret


  • A user-assigned 64-bit identifier for the key.

The user may assign a new keyId each time they announce a new key of a given keyType. A keyId value is useful when invoking certain DSNP Operations in order to indicate which key was used to encrypt data. It may also provide a hint to the user if they ever need to regenerate their private key (for example, many key derivation functions enable the use of a subkey identifier to deterministically create a subkey from a root key).


  • MUST be a public key of an allowed algorithm for keyType, encoded in multikey format

The multikey encoding of public keys is described in the draft did:key Method specification. The byte encoding consists of a multicodec key identifier (as a varint) followed by the public key's binary data in the codec's described format.

If serializing the multicodec value as a string, base58btc encoding is recommended. For example, the string z6LStiZsmxiK4odS4Sb6JmdRFuJ6e1SYP157gtiCyJKfrYha decodes as a Base58 string using the x25519-pub multicodec value with a 32-byte raw key of 0xfd3384e132ad02a56c78f45547ee40038dc79002b90d29ed90e08eee762ae715.