庖丁解牛

3/02/2010

NXP Mifare Plus 恩智浦提供非接觸式卡片系統新一層安全保護

重點摘要︰有AES以及CRYPTO1加密功能, 向下相容, 防金鑰更新中斷, 7-Byte唯一ID和亂數ID, 距離估計(防止relay)。

防金鑰更新中斷機制, 如果卡片在key更新時被有心人(攻擊者)強制中斷, 會自動認定失敗並回復至先前的key ~~(我未看先猜是dual-mode保護機制, 也就是存兩組key, 只有更新成功才把pointer指到新的那組, 從規格2x128bit AES key應該可以證實我的猜測)。~~

Key applications(主要應用)

交通 Public transportation
存取管理 Access management, e.g. employee, school or campus cards
道路電子收費 Electronic toll collection
停車Car parking
認同卡 Loyalty programs

Key features(功能規格)

2 or 4-KB EEPROM
Simple fixed memory structure compatible with MIFARE Classic 1 K (MF1ICS50), MIFARE Classic 4 K (MF1ICS70)
Access conditions freely configurable
Smooth migration from MIFARE Classic to MIFARE Plus security level supported
Open standard AES crypto for authentication, integrity and encryption
Common Criteria Certification: EAL4+ for IC HW and SW
ISO/IEC 14443-A unique serial number, 4 or 7 byte and random IDs
Multi-sector authentication, multi-block read and write
Anti-tear function for writing AES keys
Keys can be stored as MIFARE Classic CRYPTO1 keys (2 x 48 bit per sector) or as AES keys (2 x 128 bit sector)
Supports virtual card concept
High data rates up to 848 kbit/s
Available in MOA4 modules or 8-inch sawn bumped wafer

NXP MIFARE Plus is based on open global standards both for air interface and cryptographic methods. It is available in two versions: MIFARE Plus S, the Slim version, for straightforward migration of MIFARE Classic systems, and MIFARE Plus X, the eXpert version, which offers more flexibility to optimize the command flow for speed, privacy and confidentiality. MIFARE Plus X offers a rich feature set, including proximity checks against relay attacks.

MIFARE Plus is fully functional backwards compatible with MIFARE Classic 1 K / 4 K. Interoperability with MIFARE Classic has been verified by the independent MIFARE Certification Institute. MIFARE Plus offers the possibility to issue cards seamlessly into existing MIFARE Classic applications, before the infrastructure is upgraded. Once the security upgrades are in place, MIFARE Plus cards can be switched to a more secure mode in the field with no customer interaction necessary. AES (advanced encryption standard) is then being used for authentication, encryption and data integrity.

MIFARE Plus supports high-speed communication between card and terminal at up to 848 kbps/s, for time critical services. The read range of up to 10 cm increases the convenience of the touch-and-go experience.

Security Levels(可以切換幾個安全等級)

MIFARE Plus cards supports one pre-personalization and 3 security levels. Cards operate in one security level at any given time and can only be switched to a higher level.

Security Level 0 (預先燒錄key, ~~AES和CRYPTO1保護memory?~~)
MIFARE Plus cards are pre-personalized with configuration keys, level switching keys, MIFARE Classic CRYPTO1 and AES keys for the memory.
Security Level 1 (向下相容模式)
In this level the cards are 100% functionally backwards compatible with MIFARE Classic 1K / 4K cards. Cards work seamlessly in existing MIFARE Classic infrastructure.
Security Level 2 (用AES做reader認證, 傳輸中用CRYPTO1做資料加密)
Mandatory AES authentication. MIFARE Classic CRYPTO1 for data confidentiality.
Security Level 3 (全部用AES做reader認證, 傳輸資料加密, 資料檢查碼, 額外提供距離偵測)
Mandatory AES for authentication, communication confidentiality and integrity. Optional proximity detection (MIFARE Plus X only).

自動防中斷機制, 如果卡片在key更新時被有心人(攻擊者)強制中斷, 會自動認定失敗並回復至先前的key, ~~(我未看先猜是dual-mode保護機制, 也就是存兩組key, 只有更新成功才把pointer指到新的那組, 從規格2x128bit AES key應該可以證實我的猜測)~~

An automatic anti-tear mechanism is available for secure deployment of rolling keys. If a card is removed from the field during a key update, it either concludes the update or automatically falls back to the previous key. NXP recommends 7Byte UID, but offers 4B UID versions of MIFARE Plus during migration. MIFARE Plus is available in the proven MOA4 module and as sawn bumped wafers, no changes for existing manufacturing processes necessary.

Product leaflet

You can download the product leaflet here.

2/04/2010

RFID Tag ID越長, 讀取率越低

原文 http://www.rfidjournal.com/article/articleview/7336/1/82/
在18000-6系列的標籤有4個memory bank
2009年初, NXP和Alien開始生產有多512bit的標籤
有人開始辯論應配置在~~MB00~~MB01, 也就是UID的位置,
或是配置在MB11, 也就是User自行定義的區塊(存放產品特定資料)
這會影響不同系統的互相操作性, 以及應用的處理流程。

米其林輪胎有應用RFID來追蹤輪胎的長足經驗。
實驗證實如果UID從96bit加長到240bit, 讀取率會下降30%
研究同時指出, 讀取器只能在singulation (防碰撞階段)讀取User memory (MB11)。
因此如果要以TID本身當作防碰撞機制, 會很有問題。
UID要短, 資料就還是乖乖的存放在User memory (MB11)。

[心得]
據我的瞭解, 防碰撞機制有幾種方法, 樹狀(tree-based)或是 Aloha (標籤自行設定Time-slot回答)等等。上面這篇文章探討的應該是樹狀的防碰撞機制。

2/03/2010

EPCglobal US 2009調查發現RFID應用在消費者包裝品上取得一定基礎

原文 http://www.rfidjournal.com/article/view/7361/1

重點整理
[Cons]
根據2009年調查86%已採用或導入中的廠商，約42%取得最高100萬美金的利潤。根據這份調查，沒有任何一家廠商是在等待RFID價格下滑，這可視為一項指標：RFID價格不再是讓人裹足不前的因素。當然因為這份調查主要是EPCglobal US成員，可能有所偏頗。

99%的棧版(pallet)讀取率和82%的包裝盒讀取率說明我們已可減輕對於金屬物讀取率的憂慮。開發商可轉而嘗試開發不同的標籤和天線設計以符合各種使用者的需求。

[Pros]
根據2009年調查, 參與廠商大致分成衣服、自動化、化學、消費者電子產品、快速移動的消費者產品、免費食物、一般採購。65%已經採用EPC系列產品，21%嘗試導入，7%尚未導入。

83%指出導入原因是基於貿易夥伴的要求(大部分仍來自於Wal-Mart)。實際上這些公司很少利用RFID產生的data進一步產生新的價值。