btoob

Documentation

Overview

Package btoob decodes Bluetooth Out-Of-Band (OOB) pairing records — the "tap-to-pair" payload carried by an NFC handover tag and the Bluetooth Secure Simple Pairing OOB data block.

Two MIME types carry these records in an NDEF message:

• application/vnd.bluetooth.ep.oob — BR/EDR ("Easy Pairing"): a 2-byte little-endian OOB Data Length (counting itself) + a 6-byte little-endian Bluetooth Device Address (BD_ADDR), followed by optional EIR attributes (the same (length, AD-type, data) grammar as a BLE advertisement).
• application/vnd.bluetooth.le.oob — Bluetooth LE: a bare sequence of AD structures, including the LE Bluetooth Device Address (0x1B) and LE Role (0x1C) that an LE pairing needs.

Decoding such a record recovers the peer's Bluetooth address, device class / role, local name, and the Secure-Simple-Pairing OOB key material (hash C / randomizer R, or the LE SC confirmation/random values) that a tag offers for an authenticated tap-to-pair exchange.

Wrap-vs-native: native. The EIR/AD walk is already implemented in internal/ble (DecodeGAPBytes); this package adds only the thin BR/EDR framing header (length + BD_ADDR) and routes both variants through that shared walker. No third-party dependency is warranted. The BR/EDR framing and the LE Role / device-address value formats are taken from the Bluetooth Core Specification Supplement Part A and the NFC Forum "Bluetooth Secure Simple Pairing Using NFC" application document, as implemented in the ndeflib reference library — verified, not recalled.

Deferred: the OOB key material (Simple Pairing Hash C-192/256 0x0E/0x1D, Randomizer R 0x0F/0x1E, LE SC Confirmation 0x22 / Random 0x23, Security Manager TK 0x10) is surfaced as raw hex via the EIR walker — it is opaque key bytes, not a structure to interpret. Full Class-of-Device minor/service-class tables are device-major specific and left raw beyond the Major Device Class.

Index

• type Result
  • func DecodeBREDR(b []byte) (*Result, error)
  • func DecodeHex(variant, hexStr string) (*Result, error)
  • func DecodeLE(b []byte) (*Result, error)

Types

type Result

type Result struct {
	// Variant is "br_edr" or "le".
	Variant string `json:"variant"`
	// DeviceAddress is the mandatory BD_ADDR for a BR/EDR record
	// (MSB-first display form). Empty for an LE record, whose
	// address travels as the LE Bluetooth Device Address AD type.
	DeviceAddress string `json:"device_address,omitempty"`
	// OOBDataLength is the declared BR/EDR OOB Data Length field
	// (counts itself); nil for an LE record.
	OOBDataLength *int `json:"oob_data_length,omitempty"`
	// EIR is the decoded EIR / AD-structure block.
	EIR *ble.GAPAdvertisement `json:"eir,omitempty"`
	// Notes collects non-fatal observations.
	Notes []string `json:"notes,omitempty"`
}

Result is a decoded Bluetooth OOB record.

func DecodeBREDR

func DecodeBREDR(b []byte) (*Result, error)

DecodeBREDR decodes a BR/EDR ("Easy Pairing") OOB record: 2-byte little-endian OOB Data Length + 6-byte little-endian BD_ADDR + optional EIR.

func DecodeHex

func DecodeHex(variant, hexStr string) (*Result, error)

DecodeHex decodes a hex-encoded OOB record. variant selects the framing: "le" / "ble" for application/vnd.bluetooth.le.oob, anything else ("br_edr", "bredr", "ep", "") for the BR/EDR Easy Pairing record.

func DecodeLE

func DecodeLE(b []byte) (*Result, error)

DecodeLE decodes a Bluetooth LE OOB record: a bare sequence of AD structures.