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A Secure RFID deactivation/activation mechanism for customer service and consumer shopping. ( speaker ). Information Security Lab. National Chung Hsing University, TAIWAN. Yu-Yi Chen, Zhen-Jie Qiu, Jun-Chao Lu, Jinn-Ke Jan. OUTLINE. Introduction Environments
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A Secure RFID deactivation/activation mechanism for customer service and consumer shopping (speaker) Information Security Lab. National Chung Hsing University, TAIWAN Yu-Yi Chen, Zhen-Jie Qiu, Jun-Chao Lu, Jinn-Ke Jan
OUTLINE • Introduction • Environments • Our Scheme • Analysis • Conclusions
Introduction • We propose a purchase and after-sales service RFID scheme for shopping mall environment. • The location privacy, confidentiality, data integrity, and some security protections are achieved in this proposed mechanism.
Introduction Architecture of RFID system
Introduction attacker location threat • The interceptor can create a movement profile by tracing the RFID tag’s location
Environments Roles • the server (S) • the reader (R) • the RFID membership card (m-type tag) • the Goods tag (g-type tag) RFID membership Card Goods Tag
Environments Protect consumer privacy Benefits RFID membership Card Faster checkout Goods Tag
Environments Shopping Scenarios • Theconsumer uses his membership card to log on the shopping cart’s reader. • As the goods are picked up and scanned, the corresponding information is displayed on the shopping cart’s reader. • The goods in the shopping cart are pre-scanned, so the transaction can be immediately completed. • After purchasing, the tags attached on the goods should be deactivated. a b c d
OUR SCHEME The notations The encryptedsecret key is generated by server(in advance) Kcg = h(ei , Dj ) The deactivate/activate key is generated by the m-type tag ( membership card)
Shopping phase(1): authentication server Cart reader RFID Tag (3)1. γ1 , γ2 ,Txi, ν bypass to server Query,γ1 Txi= Epk(Kxi) by server (1) Gen γ1 (2) 1.Gen γ2 2. ν = h ( kxi , γ1 ) 2.Kxi’=Dsk ( Txi ) , v ? = h ( Kxi’, γ1 )
Shopping phase(2): renew RFID’s secret key and mutual authentication Cart’s reader RFID Tag α1, β1 ,α2, β2 bypass toRFID Tag server (3) 3. gen newKxi ’=h(Kxi ), Txi’=Epk(Kxi’) 4.α1 = h (Kxi , γ2)⊕ ( w|| Kxi’ || Txi’), β1 = h ( w , Kxi’ , Txi’ , γ2 ) 5.α2=h ( w, γ2) ⊕△, △= ni ,if M-tag Vg , if g-tag β2=h(△, γ2) (4) 1.( w’ ||Kxi”||Txi”)= α1 ⊕h (Kxi, γ2) β1?=h ( w’ , Kxi”, Txi”, γ2 ) in case of m-type tag: generates a shopping pseudonym ni , shopping token w and keeps the record of (ni , membershipi ) in case of g-type tag: generates the shopping token w and the signed receipt Vg(includes the serial number of the shopping mall, goods’ price, transaction time). The shopping token w is shared by m-tag and all g-tags with the help of cart reader’s bypassing. 2. △’= α2⊕h ( w’, γ2) β2 ?= h ( △’, γ2) △’= ni ,if m-tag Vg ,if g-tag
Check out & deactivate the g-tag m-tag Cart’s reader g-tag α2 , β2 (1) Query (2) ni,γ1 α1, β1, γ2 m-tag responses the shopping pseudonym ni the record of (ni , memberi )is kept by the server for authentication (4) 1.Dj’=α1⊕ h (Kci, γ1) 2.β1 ?= h (Dj’, γ1) (3) 1.bypass to the server, and the server finds ni ’s memberi & it’s secret key Kci 2. get current time Dj 3. α1=h(Kci, γ1) ⊕Dj , β1=h ( Dj, γ1) 4. generates γ2 3.Kcg = h ( ei , Dj’) 4.δ=w ⊕( Kcg|| Dj’) ν=h ( Kcg,Dj’, γ2 ) 5.α2=h ( Kci, γ2) ⊕(δ|| ν) β2=h ( δ, ν, γ2 ) The deactivate keyKcg is generated by m-tag
m-tag Cart’s reader g-tag Query, δ’, ν’, γ2 (5) α2 , β2bypass to the server 1. (δ’|| ν’) =α2⊕h(Kci, γ2) 2 . β2?=h ( δ’, ν’,γ2) The server computes the δ’ and sent it to all g-tags g-tags inside cart (6) 1.(Kcg’||Dj’)= δ’⊕w ν’?=h(Kcg’,Dj’, γ2) 2. Store Kcg, Dj 3. set privacy bit on
m-tag (1)Query (3) Query, Dj , γ1 (2) Dj , γ1 Tci, ν1,α1, β1 , γ2 δ' After-sales service phase (1) g-tag reader with server (4) 1.Generateγ2 2. ν1=h ( kci , γ2 ) 3.Kcg = h ( ei , Dj ) 4. δ=h (Kcg, γ1) 5. α1=h (Kci , γ1) ⊕δ 6. β1 = h (δ, γ1) m-tag’s authentication (5) γ1 , γ2 ,Tcibypass to server 1. Kci’=Dsk(Tci), ν1?=h(Kci’, γ2) 2. new key Kci”=h ( Kci’) , Tci”=Epk(Kci”) Activate keyKcg is recovered by m-tag 3 . δ’ = α1 ⊕ h ( Kci’, γ1) 4. β1 ?=h (δ’, γ1 ) (6) 1.If h(Kcg, γ1)=δ’ ? set privacy bit off Activate the g-tag 2. ν2=h (kgi, γ1)
Tgi ,, ν2, Vg α2, β2 After-sales service phase (2) g-tag m-tag Reader with server (7) Kgi’=Dsk(Tgi), ν2 ?=h ( Kgi’ , γ1) if correct, then the authentication of g-tag is done and handle the after-sales service and renew the secret key of m-tag. Update the new secret key of m-tag α2=h(Kci’, γ2)⊕(Kci ”||Tci”) β2=h ( Kci ”,Tci ”,γ2) (8) (Kci’’||Tci’’)=α2⊕h(Kci, γ2), β2?=h(Kci”,Tci”, γ2)
Analysis Dj, r1 Tci Location privacy • The deactivated g-type tag only responses a non-characteristic transaction time Dj. • Those g-type tags will not cause the location privacy problem. • The m-type tag’s pseudonym Tci will be updated after authentication. • m-type tag will not be tracked or monitored by the attacker
Analysis Confidentiality • Transmitted messages are always protected by the one-way Hash and XOR operations. • To do the mutual authentication, PKC and challenge-response both are employed.
Conclusions • Our proposal provides the commercial benefits of the company, and may satisfy the consumers’ requirements. • Tracking can be prevented by deactivating the tag of purchased goods. • Consumers may enjoy the convenient check-out service with “peace of mind”. • The confirm process for after-sales service is improved by using more efficient “receipt-less” proof.
OUR SCHEME A. Shopping phase server m-type tag Step1: generates a challenge number γ1, Step3: Kci’’ = Dsk(Tci) γ =? h(Kci ‘‘, γ1) if so, gen’s w Kci’ = h(Kci) Tci ‘= Epk(Kci’) α1=h(Kci,γ2)⊕(w,Kci’,Tci’) β1 =h(w, Kci’,Tci ‘,γ2) α2=h(w,γ2)⊕ni β2 =h(ni ,γ2) γ1 Step2: generates a challenge number γ2, γ = h(Kci , γ1) Tci = EPK(Kci) Step4: α1⊕h(Kci’,γ2)→(w,Kci’,Tci) β1 =? h(w, Kci’,Tci ,γ2) Tci , γ, γ2 α1,β1 Authentication is done • RFID-equipped shopping cart is used for authenticating the consumer’s ID and inquiring the Goods’ information. • All of the m-type tags get a common shopping-token after verification.
OUR SCHEME A. Shopping phase server g-type tag Step1: generates a challenge number γ1, Step3: Kgi’ = Dsk(Tgi) γ =? h(Kgi ‘, γ1) if so, α1=h(Kgi’,γ2)⊕(w,Kgi’,Tgi) β1 =h(w, Kgi’,Tgi ,γ2) γ1 Step2: generates a challenge number γ2, γ = h(Kgi , γ1) Tgi = EPK(Kgi) Step4: α1⊕h(Kgi’,γ2)→(w,Kgi’,Tgi) β1 =? h(w, Kgi’,Tgi ,γ2) Tgi , γ, γ2 Authentication half done α1,β1 Authentication is done • RFID-equipped shopping cart is used for authenticating the consumer’s ID and inquiring the Goods’ information. • All of the g-type tags get a common shopping-token after verification.
OUR SCHEME B. Purchasing phase • All the g-type tags are deactivated for protecting the location privacy of the consumer. • The m-type tag generate the deactivate/activate key by the corresponding information and its secret. • The deactivate/activate key is not necessary to be recorded in the m-type tag.
OUR SCHEME C.After-sales service phase • The g-type tag is activated and verified. • The m-type tag generate the deactivate/activate key by the corresponding information and its secret.
OUR SCHEME A. Shopping phase Authentication half done And check h(w’,Kxi’’,Txi’’,ν2)=? β1 Authentication is done • RFID-equipped shopping cart is used for authenticating the consumer’s ID and inquiring the Goods’ information. • All of the m-type tag and the g-type tags get a common shopping-token after verification. • The m-type tag gets a pseudonym for this transaction • The g-type tag acquires a signed receipt, respectively
伺服器藉由購物代號進行身份確認 伺服器安全傳送交易時間值 Dj 驅動電子標籤 執行以下程序 利用交易時間值 Dj 及紀錄在會員卡上之 金鑰種子ei 產生關閉金鑰 Kcg 用共享秘密(購買標記值)保護關閉金鑰及交易時間值,並傳送至商品Tag 確認完金鑰及交易時間後 1.儲存關閉金鑰和交易時 間值 2.商品Tag 關閉自己 Check out & deactivate the g-tag Cart’s reader G-tag M-tag
售後服務中心 商品Tag 連接伺服器之Reader RFID會員卡 無線通道 無線通道 協定中角色 (伺服器和讀取器間為安全通道) 機制分為1. 進行購物階段 ( 賣場中)2. 結帳並關閉商品標籤階段 ( 賣場中)3. 售後服務之商品標籤開啟階段 ( 售後服務中心)
回傳Dj Forward Dj至會員卡 伺服器認證商品Tag 驅動電子標籤 執行以下程序 利用交易時間值 Dj 及紀錄在會員卡上之 金鑰種子ei 產生開啟金鑰 Kcg 收到此開啟金鑰後,和已經儲存在商品Tag上之金鑰進行比對,若比對成功則開啟自己 用共享秘密保護開啟金鑰,並傳送至商品Tag 售後服務之商品標籤開啟階段基本流程 商品Tag RFID會員卡 Reader with server 此時在保固期之商品Tag 即可被判讀,並經過驗證 後由商家提供售後服務
Tgi ,, ν2, Vg α2, β2 After-sales service phase (2) g-tag M-tag Reader with server 若在保固期中,則商品Tag將可被驗證 (7) Kgi’=Dsk(Tgi), ν2 ?=h ( Kgi’ , γ1) 驗證商品Tag及其銷售憑證 Vg,並由賣場提供售後服務 此時於(5)中伺服器所產生的RFID會員卡新金鑰,將被傳到會員卡中 α2=h(Kci”, γ2)⊕(Kci ”||Tci”) β2=h ( Kci ”,Tci ”,γ2) (8) (Kci’||Tci’)’=α2⊕h(Kci, γ2), β2?=h(Kci”,Tci”,γ2)
Analysis Resist replay attack • The tag authenticates itself to the server, its response is generated according to the random challenge determined by the server. • The server authenticates itself to the tag. The replay attack can be resisted due to the authentication is based on challenge-response.