### SLEEP File Types

    key
        no header, raw bytes
    tree
        magic: 0x05025702
        entry-size: 40 bytes
        algorithm name: 'BLAKE2b' (len=7)
        entry: 32-byte BLAKE2b node hash + 8-byte Uint64BE length
    data
        no header, raw bytes
    signatures
        magic: 0x05025701
        entry-size: 65
        algorithm name: 'Ed25519' (len=7)
        entry: 64-byte Ed25519 signature
    bitfield
        magic: 0x05025700
        entry-size: 3328
        algorithm name: '' (len=0)
        entry: 1024 bytes data, 2048 bytes tree, 256 bitfield