Crate qhermes_kernel 

Cryptographic and authorization primitives for QHermes delegation chains.

Layers

Crypto     — key derivation and ML-DSA-65 signing/verification
Policy     — permission encoding, scope subset enforcement, caveat evaluation
Delegation — credential issuance and chain verification
Wire       — credential chain serialization and deserialization

Permission format

[res_len: u8][resource bytes][verb_len: u8][verb bytes]

Wire format

[version: u8 = 0x01][count: u32 LE][credentials...]
[issuer_pk: PK_SIZE][signature: SIG_SIZE][payload_len: u32 LE][payload bytes]

Timestamps

All Timestamp values are seconds since the Unix epoch. Passing milliseconds or nanoseconds produces incorrect caveat evaluation.

Domain separation

IdentityIsland::derive folds deployment and context into the HKDF info parameter. Different deployment values yield independent key material even when sharing the same master.

Structs

BoundedCaveats

Validated sequence of fixed-size caveat records.

BoundedScope

Validated, non-empty TLV sequence of permissions.

Credential

One link in a serialized credential chain as it appears on the wire.

DelegationManifest

Parameters for issuing a credential in a delegation chain.

Depth

Sequential position of a credential within its delegation chain. The first credential issued by the root has depth 1.

IdentityIsland

ML-DSA-65 identity deterministically derived from a master seed via HKDF-SHA3-512.

PublicKey

Reference to a PK_SIZE-byte ML-DSA-65 public key.

ScopeIter

Signature

Reference to a SIG_SIZE-byte ML-DSA-65 signature.

Timestamp

Timestamp in seconds since the Unix epoch.

Enums

KernelError

Errors returned by QHermes kernel operations.

Role

Role encoded in a credential payload.

Constants

CAVEAT_SIZE

Byte length of one serialized caveat record: 1-byte tag + 8-byte timestamp.

CREDENTIAL_FIXED_SIZE

Fixed bytes per credential record, excluding the payload: PK_SIZE + SIG_SIZE + 4 (payload_len field).

MAX_CAVEATS

Maximum number of caveats in a credential.

MAX_DEPTH

Maximum depth of a delegation chain. Longer chains are rejected at issuance, verification, and deserialization.

MAX_PAYLOAD_SIZE

Maximum byte length of a payload, assuming all permissions at maximum TLV size and all caveat slots occupied.

MAX_SCOPE_PERMS

Maximum number of permissions in a credential scope.

PERM_TLV_MAX

Maximum byte length of the TLV encoding of one permission: 1 (res_len) + RESOURCE_LEN + 1 (verb_len) + VERB_LEN.

PK_SIZE

Byte length of an ML-DSA-65 public key (verifying key).

RESOURCE_LEN

Maximum byte length of the resource field in a permission. Fits a u8-typed TLV length prefix.

SEED_SIZE

Byte length of the HKDF seed and derived key material.

SIG_SIZE

Byte length of an ML-DSA-65 signature.

VERB_LEN

Maximum byte length of the verb field in a permission. Fits a u8-typed TLV length prefix.

Traits

IdentitySigner

Signing interface for any ML-DSA-65 identity: in-memory keys, HSM, TPM, or enclave.

Functions

enforce_scope_subset

Checks that every permission in child is covered by at least one permission in parent.

evaluate_caveats

Evaluates all caveats in caveats against now.

issue_credential

Serializes manifest into payload_out and signs it into sig_out.

not_after

Constructs a not-after caveat record.

not_before

Constructs a not-before caveat record.

perm_tlv

Encodes a (resource, verb) permission into out using TLV format.

read_credential_chain

Deserializes wire into chain. All slices point into wire. Returns the credential count.

verify_delegation

Verifies a credential chain rooted at root_pk against timestamp.

verify_signature

Verifies an ML-DSA-65 signature over payload under pk.

write_credential_chain

Serializes chain into out. Returns bytes written, or WireTruncated if out is too small.