Struct SseChunkBinding 

pub struct SseChunkBinding {
    pub enc_chunk_size: u32,
    pub enc_chunk_count: u32,
    pub enc_key_id: u16,
    pub enc_salt: [u8; 8],
    pub enc_plaintext_len: u64,
    pub enc_header_bytes: u32,
}

v0.9 #106: per-object SSE-S4 chunked (S4E6) geometry, stored in v3 sidecars. The salt + key_id let the GET path derive the per-chunk AES-GCM nonce + AAD without re-fetching the encrypted body’s header bytes. Salt is not secret (it lives in the on-disk S4E6 header in plaintext anyway); duplicating it here saves one HEAD/GET round-trip per Range request.

Fields

enc_chunk_size: u32

S4E6 plaintext bytes per chunk (matches --sse-chunk-size). Must be > 0 for an SSE binding to be considered valid.

enc_chunk_count: u32

Total number of S4E6 chunks in the body (= ceil(plaintext.len() / enc_chunk_size), always >= 1).

enc_key_id: u16

Keyring slot the active key was at PUT time. The GET path uses it to look up the same key for decrypt.

enc_salt: [u8; 8]

8-byte per-PUT random salt (S4E6). Fed into the nonce + AAD derivation; lives in the encrypted body’s header in plaintext anyway, so duplicating it in the sidecar leaks nothing.

enc_plaintext_len: u64

Pre-encrypt plaintext body length (= post-compress, post-frame body length). Used to validate the chunk-walk math against the encrypted body length the backend reports.

enc_header_bytes: u32

Fixed header size of the S4E6 frame (== S4E6_HEADER_BYTES = 24 today). Carried explicitly so a future S4E7-style bump doesn’t silently break v3 sidecar decode.

Implementations

impl SseChunkBinding

pub fn enc_chunk_stride(&self) -> u64

Per-chunk on-disk byte cost: ciphertext (= plaintext bytes, AES-GCM is CTR-mode) + 16-byte auth tag. Final chunk may carry fewer plaintext bytes; this helper returns the non-final chunk cost.

pub fn enc_chunk_on_disk_size(&self, chunk_idx: u32) -> u64

On-disk byte length of chunk chunk_idx. Non-final chunks carry enc_chunk_size plaintext bytes (+ 16-byte tag); the final chunk carries enc_plaintext_len - (chunk_count - 1) * enc_chunk_size plaintext bytes (+ tag).

pub fn enc_chunk_byte_offset(&self, chunk_idx: u32) -> u64

Encrypted-body byte offset of the start of chunk chunk_idx (= the chunk’s tag byte). Non-final chunks stride at enc_chunk_stride().

Trait Implementations

impl Clone for SseChunkBinding

fn clone(&self) -> SseChunkBinding

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for SseChunkBinding

impl Debug for SseChunkBinding

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for SseChunkBinding

impl PartialEq for SseChunkBinding

fn eq(&self, other: &SseChunkBinding) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for SseChunkBinding