C2SP signed-note verifier-key (vkey) encoding.
A verifier key is the text a relying party pins to recognize and check a signer's note/checkpoint signatures:
<name>+<hex(key_id)>+<base64(type_id || public_key)>where key_id = SHA-256(name || 0x0A || type_id || public_key)[:4] (big
endian). These encoders derive the key id and produce the canonical vkey
string for the two supported signature types, so a server can publish the
vkey its clients feed to MetamorphicLog.Checkpoint.verify/2 and
MetamorphicLog.Note.verify/2.
Public keys cross the boundary base64-encoded.
Summary
Functions
Encode a C2SP tlog-cosignature v1 Ed25519 (0x04) verifier key from a
cosigner name (a schema-less URL identifying the witness) and a 32-byte
Ed25519 public key (base64).
Encode a C2SP tlog-cosignature v1 ML-DSA-44 (0x06) verifier key from
a cosigner name (a schema-less URL identifying the witness) and a 1312-byte
ML-DSA-44 public key (base64).
Encode a classical Ed25519 verifier key from a key name and a 32-byte public
key (base64).
Encode a classical Ed25519 (0x01) verifier key from a key name and the
Ed25519 half of a :hybrid-suite composite public key (base64
tag || ed25519_pk || ml_dsa_pk).
Encode a hybrid composite verifier key from a key name and the
metamorphic-crypto composite public key bytes
(tag || classical_pk || ml_dsa_pk, base64).
Functions
@spec encode_cosignature_ed25519(name :: String.t(), public_key_b64 :: String.t()) :: {:ok, String.t()} | {:error, String.t()}
Encode a C2SP tlog-cosignature v1 Ed25519 (0x04) verifier key from a
cosigner name (a schema-less URL identifying the witness) and a 32-byte
Ed25519 public key (base64).
This is the vkey a log pins to verify a witness's timestamped Ed25519
cosignature lines (what deployed witnesses emit today). Returns {:ok, vkey}
or {:error, reason}.
@spec encode_cosignature_mldsa44(name :: String.t(), public_key_b64 :: String.t()) :: {:ok, String.t()} | {:error, String.t()}
Encode a C2SP tlog-cosignature v1 ML-DSA-44 (0x06) verifier key from
a cosigner name (a schema-less URL identifying the witness) and a 1312-byte
ML-DSA-44 public key (base64).
This is the vkey a log pins to verify a witness's post-quantum ML-DSA-44
cosignature lines (the cosignature spec's recommended type for new
deployments). Returns {:ok, vkey} or {:error, reason}.
@spec encode_ed25519(name :: String.t(), public_key_b64 :: String.t()) :: {:ok, String.t()} | {:error, String.t()}
Encode a classical Ed25519 verifier key from a key name and a 32-byte public
key (base64).
Returns {:ok, vkey} or {:error, reason} (invalid name or a key that is not
32 bytes).
@spec encode_ed25519_from_hybrid(name :: String.t(), public_key_b64 :: String.t()) :: {:ok, String.t()} | {:error, String.t()}
Encode a classical Ed25519 (0x01) verifier key from a key name and the
Ed25519 half of a :hybrid-suite composite public key (base64
tag || ed25519_pk || ml_dsa_pk).
This is the vkey a stock Ed25519-only C2SP witness needs to verify the
0x01 line of a dual-signed checkpoint (Checkpoint.sign_dual/5): the
witness registration bundle for an origin is its hybrid vkey
(encode_hybrid/2) plus this derived vkey. The derivation is deterministic.
Composite keys without an Ed25519 classical half (matched-suite Ed448/P-521,
pure-PQ) are rejected.
Returns {:ok, vkey} or {:error, reason}.
Example
{:ok, witness_vkey} =
MetamorphicLog.VerifierKey.encode_ed25519_from_hybrid("origin/log", composite_pk_b64)@spec encode_hybrid(name :: String.t(), public_key_b64 :: String.t()) :: {:ok, String.t()} | {:error, String.t()}
Encode a hybrid composite verifier key from a key name and the
metamorphic-crypto composite public key bytes
(tag || classical_pk || ml_dsa_pk, base64).
This is the public key stored as a namespace's signing key. Returns
{:ok, vkey} or {:error, reason} (invalid name or empty key).
Example
{:ok, vkey} = MetamorphicLog.VerifierKey.encode_hybrid("metamorphic.app/log", pk_b64)