LHC Grid Computing School 그리드 보안 기술 2016. 2. 3

LHC Grid Computing School 01 02 03 04 05 개요 기초암호 X.509 PKI SSL/TLS 결론 Contents LHC Grid Computing School

LHC Grid Computing School 1. 개요 What is Security Threat Grid Computing? Sharing Resources LHC Grid Computing School

Characteristics of Grid Computing Environment Large & dynamic user population and resources pool Dynamic resource acquisition and release Dynamic creation and destruction of a variety of network connection An individual user will be associated with different local name spaces, credentials, or accounts at different sites LHC Grid Computing School

e.g. Security Architecture in Globus PKI (CAs and Certificates) SSL/TLS Proxies and Delegation for Secure SSO For Authentication and message Protection SSO: Single Sign-On PKI: Public Key Infrastructure CA: Certification Authority SSL: Secure Socket Layer TLS: Transport Layer Security LHC Grid Computing School

In This Class, we are going to.. understand mechanisms behind security process LHC Grid Computing School

LHC Grid Computing School 보안의 목표 ALICE BOB State of Illinois John Doe 755 E. Woodlawn Urbana IL 61801 BD 08-06-65 Male 6’0” 200lbs GRN Eyes State of Illinois Seal 기밀성(Confidentiality) 사용자 인증 (Authentication) 무결성 (Integrity) LHC Grid Computing School

LHC Grid Computing School 보안의 목표 사용자 인증 기 밀 성 무 결 성 부인 봉쇄 그런 거 보낸 적 없는데? LHC Grid Computing School

LHC Grid Computing School     LHC Grid Computing School

LHC Grid Computing School 2. 기초 암호 If he had anything confidential to say, he wrote it in cipher, that is, by so changing the order of the letters of the alphabet, that not a word could be made out. If anyone wishes to decipher these, and get at their meaning, he must substitute the fourth letter of the alphabet, namely D, for A, and so with the others. —Suetonius, Life of Julius Caesar  LOVE (Shift 4) ILSB 평문 암호문 암호 알고리즘 암호키 LHC Grid Computing School

LHC Grid Computing School 관용 암호 알고리즘 Conventional Cryptography Symmetric Cryptography One-key Cryptography C=Eke[M] Dkd[C]=M 암호화 복호화 M C M: 평문 E: 암호화 알고리즘 C: 암호문 Ke: 암호화 키 D: 복호화 알고리즘 Kd: 복호화 키 LHC Grid Computing School

LHC Grid Computing School Ke = kd 송신자와 수신자 사이의 공통의 키 AES, DES, Skipjack, IDEA, FEAL, LOKI, GOST, SEED 송신자 C = Ek[M] 수신자 Dk[C] = M C K = LHC Grid Computing School

LHC Grid Computing School Block Cipher P1 Ek C1 P2 C2 P3 C3 encrypt each plaintext block separately LHC Grid Computing School

LHC Grid Computing School Stream Cipher =  Key Plaintext Stream Ciphertext LHC Grid Computing School

LHC Grid Computing School 블록 암호 예제 – 시저 암호 ... D A T E G W H 각 바이트를 치환표에 의하여 암호화 LHC Grid Computing School

블록 암호 예제 - Electronic Code Book 64 bits DES 키 64비트 블록으로 나누어 각각을 암호화 LHC Grid Computing School

블록 암호 예제 – Cipher Block Chaining 64 bits DES 키 전단계의 암호문 블록이 다음 단계의 입력에 관여함 LHC Grid Computing School

Enigma (2차 세계대전에서 독일군 사용) LHC Grid Computing School

DES – Data Encryption Standard Designed by IBM, with modifications proposed by the National Security Agency US national standard from 1977 to 2001 De facto standard Block size 64 bits; Key size 56 bits 16-rounds Designed mostly for hardware implementations Considered insecure now vulnerable to brute-force attacks LHC Grid Computing School

Attacking Block Ciphers Types of attacks to consider known plaintext: given several pairs of plaintexts and ciphertexts, recover the key (or decrypt another block encrypted under the same key) how would chosen plaintext and chosen ciphertext work? Standard attacks exhaustive key search dictionary attack differential cryptanalysis, linear cryptanalysis Side channel attacks. DES’s main vulnerability is short key size. LHC Grid Computing School

LHC Grid Computing School DES 해독기 LHC Grid Computing School

AES – Advanced Encryption Standard In 1997, NIST made a formal call for algorithms stipulating that the AES would specify an unclassified, publicly disclosed encryption algorithm, available royalty-free, worldwide. Goal: replace DES for both government and private- sector encryption. The algorithm must implement symmetric key cryptography as a block cipher and (at a minimum) support block sizes of 128-bits and key sizes of 128-, 192-, and 256-bits. In 1998, NIST selected 15 AES candidate algorithms. On October 2, 2000, NIST selected Rijndael (invented by Joan Daemen and Vincent Rijmen) to as the AES. LHC Grid Computing School

LHC Grid Computing School 관용키 암호 알고리즘의 문제점 C=Eke[M] Dkd[C]=M 암호화 복호화 M C LHC Grid Computing School

공개키 암호 알고리즘(Public Key Cryptography) 암호화 복호화 M C M C=Eke[M] Dkd[C]=M A B A의 비밀키 B의 비밀키 A의 공개키 B의 공개키 B의 공개키 A의 공개키 LHC Grid Computing School

LHC Grid Computing School 기밀성 C = EKUb[M] C DKRb[C] = M KUb Kua, Kub 공개키 목록 LHC Grid Computing School

전자서명(Digital Signature) 제공 기능 요구 조건 + + 메시지 인증 사용자 인증 부인 봉쇄 위조 불가 서명자 인증 부인 불가 변경 불가 재사용 불가 LHC Grid Computing School

LHC Grid Computing School A 문서 (M) 암호화 EKRa[M] B KRa (A의 개인키) LHC Grid Computing School

LHC Grid Computing School 비교 (전자서명 확인) B EKRa[M] 복호화 M KUa (A의 공개키) LHC Grid Computing School

(Message Integirty Code) 해쉬함수 메시지로부터 출력을 계산하는 것은 용이 출력으로부터 메시지를 계산하는 것은 계산상 불가능 서로 같는 해쉬값을 갖는 두 메시지를 찾는 것은 계산상 불가능 메시지 인증과 전자서명의 효율을 높이기 위해 사용 M 해쉬 함수 [임의의 길이의 출력] (Message Integirty Code) MIC [임의의 길이의 메시지] LHC Grid Computing School

LHC Grid Computing School 전자서명 생성 II A 문서 (M) 해쉬 함수 H(M) 암호화 M EKRa[H(M)] KRa (A의 개인키) B LHC Grid Computing School

LHC Grid Computing School 주문서 다음과 같은 내용으로 주문을 요청합니다. 1999.10.30 홍길동 ------BEGIN Digital Signature ------ Content-Type: application/x-pkcs7 -signature; Content-Disposition: attachment; Content-Transfer-Encoding: base64 ggM7oAMCAQICFEQ41iugpRpD1VzRmFQZQnk TWVtZSBSb290IENBMQ4wDAYDVQQKEwVTTWV KoZIhvcNAQkEMRYEFEoe7hq0yyoZEWUp7gA xI5z0pabAAAAAAAAxI5z0pabAAAAAAAAxI5 ------END Digital Signature ------ 주문서 다음과 같은 내용으로 주문을 요청합니다. 1999. 10. 30 홍 길 동 LHC Grid Computing School

LHC Grid Computing School 전자서명 확인 II M 해쉬 함수 H(M) 비교 (전자서명 확인) B EKRa[M] 복호화 H(M) KUa (A의 공개키) LHC Grid Computing School

LHC Grid Computing School 기밀성과 전자서명 EK [ M || EKRa [H(M)] ] || EKUb[K] (K = Session Key) 송신자 A 수신자 B LHC Grid Computing School

LHC Grid Computing School 전자서명 생성 가나다라 Ks.14dalx 가나다라 암호화 (RSA) Ks.14dalx A의 비밀키 A B LHC Grid Computing School

LHC Grid Computing School 주문서 다음과 같은 내용으로 주문을 요청합니다. 1999.10.30 홍길동 ------BEGIN Digital Signature ------ Content-Type: application/x-pkcs7 -signature; Content-Disposition: attachment; Content-Transfer-Encoding: base64 ggM7oAMCAQICFEQ41iugpRpD1VzRmFQZQnk TWVtZSBSb290IENBMQ4wDAYDVQQKEwVTTWV KoZIhvcNAQkEMRYEFEoe7hq0yyoZEWUp7gA xI5z0pabAAAAAAAAxI5z0pabAAAAAAAAxI5 ------END Digital Signature ------ 주문서 다음과 같은 내용으로 주문을 요청합니다. 1999. 10. 30 홍 길 동 LHC Grid Computing School

LHC Grid Computing School 전자서명 확인 가나다라 서명 확인 복호화 (RSA) Ks.14dalx 가나다라 A의 공개키 B LHC Grid Computing School

LHC Grid Computing School 전자서명 확인 가나다라 서명 확인 복호화 (RSA) Ks.14dalx 가나다라 A의 공개키 B LHC Grid Computing School

LHC Grid Computing School Diffie-Hellman LHC Grid Computing School

LHC Grid Computing School Alice and Bob agree to use a prime number p = 23 and base g = 5 (which is a primitive root modulo 23). Alice chooses a secret integer a = 6, then sends Bob A = ga mod p A = 56 mod 23 = 8 Bob chooses a secret integer b = 15, then sends Alice B = gb mod p B = 515 mod 23 = 19 Alice computes s = Ba mod p s = 196 mod 23 = 2 Bob computes s = Ab mod p s = 815 mod 23 = 2 LHC Grid Computing School

LHC Grid Computing School RSA Adi Sharmir Ron Rivest Lin Addleman LHC Grid Computing School

LHC Grid Computing School

LHC Grid Computing School Select primes: p=17 & q=11 Compute n = pq =17×11=187 Compute ø(n)=(p–1)(q-1)=16×10=160 Select e : gcd(e,160)=1; choose e=7 Determine d: de=1 mod 160 and d < 160 Value is d=23 since 23×7=161= 10×160+1 Publish public key KU={7,187} Keep secret private key KR={23,17,11} sample RSA encryption/decryption is: given message M = 88 (nb. 88<187) encryption: C = 887 mod 187 = 11 decryption: M = 1123 mod 187 = 88 LHC Grid Computing School

인증기관(CA: Certification Authority) 공개키 암호방식의 문제점 사용자 개인키 보관 IC카드 활용 암호화하여 디스켓, HDD 등에 보관 상대방의 공개키에 대한 진위 여부 공개키에 대한 인증서(Certificate) 발행 인증기관: CA(Certification Authority) 신뢰할 수 있는 제 3기관 사용자의 공개키를 확인하여 인증서 발행 나 희덕이야, 이 거 내 공개키다. 희덕이의 공개키로 암호화 했으니, 병철이는 못 보겠지..  병철 승호 희덕 LHC Grid Computing School

LHC Grid Computing School 인증기관의 역할 사용자 인증기관(CA) 인증서 발행 요청 공개키 전달 공개키에 전자서명 공개키쌍 생성 인증서 저장 저장소 사용자 인증서 LHC Grid Computing School

PKI: Public Key Infrastructure root CA CA sub CA RA repository LHC Grid Computing School

LHC Grid Computing School PKI allows you to know that a given public key belongs to a given user PKI builds off of asymmetric encryption: Each entity has two keys: public and private The private key is known only to the entity The public key is given to the world encapsulated in a X.509 certificate Owner LHC Grid Computing School

LHC Grid Computing School Certificates A X.509 certificate binds a public key to a name It includes a name and a public key (among other things) bundled together and signed by a trusted party (Issuer) Name Issuer Public Key Signature LHC Grid Computing School

LHC Grid Computing School Similar to passport or driver’s license State of Illinois John Doe 755 E. Woodlawn Urbana IL 61801 BD 08-06-65 Male 6’0” 200lbs GRN Eyes State of Illinois Seal Name Issuer Public Key Signature LHC Grid Computing School

LHC Grid Computing School By checking the signature, one can determine that a public key belongs to a given user. Name Issuer Public Key Signature Hash Hash =? Decrypt Hash Public Key from Issuer LHC Grid Computing School

LHC Grid Computing School Question: Who signs certificates? Answer: A small set of trusted entities known as Certificate Authorities (CAs) Name Public Key Issuer? LHC Grid Computing School

LHC Grid Computing School CA A Certificate Authority is an entity that exists only to sign user certificates The CA signs it’s own certificate which is distributed in a trusted manner Name: CA Issuer: CA CA’s Public Key CA’s Signature LHC Grid Computing School

LHC Grid Computing School The public key from the CA certificate can then be used to verify other certificates Name Issuer Public Key Signature Hash Hash =? Decrypt Hash Name: CA Issuer: CA CA’s Public Key CA’s Signature LHC Grid Computing School

Certificate Policy(CP) Each CA has a Certificate Policy (CA) which states when and how a CA issues certificates. It states who it will issue certificates for Just like the State of Illinois only issues driver’s licenses’ for residents of the state of Illinois A CA for a grid typically only issues certificates for folks that are already approved to use resources on the grid LHC Grid Computing School

Certificate Policy (CP) A CA’s CP states how it identifies the people it issues certificates to Similar to having to show a birth certificate to get a driver’s license Some CA’s are very stringent and require similar proof of identity Others are lenient and only require proof via email LHC Grid Computing School

X.509 v3 인증서 is an IETF/ITU-T standard Standard Extensions Version Certificate serial number Signature algorithm identifier Algorithm parameters Standard Extensions Ver 1 Authority Key Identifier Issuer name Subject Key Identifier Ver 2 Not before Not after Period of validity Key Usage Ver 3 Private Key Usage Period Subject name Certificate Policies Policy Mapping Algorithm Parameters Key Subject public key info Subject Alternative Name Issuer Alternative Names Issuer unique identifier Subject Directory Attributes Basic Constraints Subject unique identifier Name Constraints Extensions Policy Constraints Extended Key Usage Field vversions All Algorithm Parameters Key Signature CRL Distribution Points LHC Grid Computing School

LHC Grid Computing School

X.509 v2 CRL Version Signature Algorithm Issuer Name This Update Next Update Revoked Certificates Certificate Serial Number CRL Extensions Revocation Date CRL Entry Extensions (opt.) Signature LHC Grid Computing School

LHC Grid Computing School 인증기관의 업무 사용자 신원 확인 인증서 발행 인증서 공개 인증서의 효력 상실 비밀키의 생성 및 관리 업무의 중단 및 관리 (1) Customer key generation & key management customer merchant CA CA’s Key management Certificate, CRL Manag. Directory System Manag. Audit Time-Stamping Services Policy Management  Certificate policy  CPS (2) I.D. info & Public Key (3) Certificate (7) Service or Products (4) Oder, Payment info, Certificate (5) access CRL (6) CRL or specific Certificate LHC Grid Computing School

H/W, Toolkit, Applications 독립적 개발 추진 4. SSL/TLS SSL : 1994년 Netscape 사에서 처음으로 제안, 현재 SSL v3. TLS : IETF TLS W/G, SSL을 개정하여 표준화 진행중 RFC 2246 : The TLS Protocol Version 1.0 네스케입 브라우저에 SSL 구현 4월 SSLRef 2.0 V2.0 V3.0 7월 초기 프로토콜 설계 11월 SSL V3.0 ‘94 ‘95 ‘96 ‘99 IE, NS Navigator: SSL 2.0, SSL 3.0, TLS 1.0(SSL 3.1) 지원 12월 SSL V2.0 7월 SSL BOF@ IETF 1월 TLS V1.0 발표 IETF TLS W/G 결성 H/W, Toolkit, Applications 독립적 개발 추진 LHC Grid Computing School

LHC Grid Computing School HTTPS TLS Handshake Protocl TLS Change Cipher Spec Protocl TLS Alert Protocol HTTP Telnet TLS Handshake Protocl HTTP TLS Record Protocol TLS Record Protocol TCP TCP IP IP LHC Grid Computing School

LHC Grid Computing School The Goals of TLS 보안 서비스 (Security) 기밀성 무결성 사용자 인증 상호호환성 (Interoperability) TLS를 이용하는 어플리케이션 간의 상호호환성 확보 (HTTP, Telnet, FTP,…) 확장성 (Extensibility) 새로운 알고리즘의 추가의 용이성 효율성 (Efficiency) Optional session caching scheme to reduce the # of connection LHC Grid Computing School

1. Pending State 1. Pending State 클라이언트 서 버 Session State 1. Pending State HP가 진행중 1. Handshake Protocol 1. Pending State HP가 진행중 2. Change Cipher Spec Protocol 2. Current State 현재 세션 상태 2. Current State 현재 세션 상태 세션 ID 인증서 압축 방법 Cipher Spec Master_Secret 세션 ID 인증서 압축 방법 Cipher Spec Master_Secret 3. Alert Protocol Connection State Server&client random server write MAC Secret client write MAC Secret server write key client write key Initialization Vector sequence numbers Server&client random server write MAC Secret client write MAC Secret server write key client write key Initialization Vector sequence numbers 4. Record Protocol LHC Grid Computing School

LHC Grid Computing School TLS 핸드쉐이크 프로토콜 핸드쉐이크의 종류 Full Handshake: 새로운 세션을 시작할 때 Abbreviated Handshake: 이전 세션을 resume하여 사용할 때 The Handshake Protocol is responsible for negotiating a session, which consists of the following items: session identifier peer certificate compression method cipher spec master secret is resumable LHC Grid Computing School

LHC Grid Computing School Full Handshake 1. Client Hello 2. Server Hello 3. Server Certificate* 5. Certificate Request* 6. Server Hello Done 7. Client Certificate* 8. Client Key Exchange 9. Certificate Verify* Change Cipher Specs 10. Finished 11. Finished T L S 클 라 이 언 트 서 버  암호알고리즘 및 키 길이 결정  서버 공개키 확보  클라이언트 인증 (Optional)  키 교환 및 서버 인증  세션정보 생성 완료 및 확인  세션정보 생성 4. Server Key Exchange* LHC Grid Computing School

LHC Grid Computing School Key Exchange Algorithms Algorithm Description Key Size Limit DHE_DSS Ephemeral DH with DSS signature None DHE_DSS_EXPORT Ephemeral DH with DSS signature DH=512 DHE_RSA Ephemeral DH with RSA signature None DHE_RSA_EXPORT Ephemeral DH with RSA signature DH=512, RSA=None DH_anon Anonymous DH, no signature None DH_anon_EXPORT Anonymous DH, no signature DH=512 DH_DSS DH with DSS-based certificates None DH_DSS_EXPORT DH with DSS-based certificates DH=512 DH_RSA DH with RSA-based certificates None DH_RSA_EXPORT DH with RSA-based certificates DH=512, RSA=None NULL No key exchange N/A RSA RSA key exchange None RSA_EXPORT RSA key exchange RSA=512 LHC Grid Computing School

LHC Grid Computing School Client Server version = 3.1 random session id = empty cipher suite = TLS_Key Exchange_WITH_Cipher_Hash (ex: TLS_RSA_WITH_RC4_128_MD5) compression method = NULL version, random, session id, cipher suite, compression method Certificate Chain: server cert. CA cert. root CA cert. server’s public key parameters certificate type = rsa_sign|dss_sign|rsa_fixed_dh|dss_fixed_dh acceptable CA DN list struct { } ServerHelloDone; LHC Grid Computing School

LHC Grid Computing School Cipher Suites TLS_NULL_WITH_NULL_NULL* TLS_RSA_WITH_NULL_MD5* TLS_RSA_WITH_NULL_SHA* TLS_RSA_EXPORT_WITH_RC4_40_MD5* TLS_RSA_WITH_RC4_128_MD5 TLS_RSA_WITH_RC4_128_SHA TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5* TLS_RSA_WITH_IDEA_CBC_SHA TLS_RSA_EXPORT_WITH_DES40_CBC_SHA* TLS_RSA_WITH_DES_CBC_SHA TLS_RSA_WITH_3DES_EDE_CBC_SHA TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA * TLS_DH_DSS_WITH_DES_CBC_SHA TLS_DH_DSS_WITH_3DES_EDE_CBC_SHA TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA* TLS_DH_RSA_WITH_DES_CBC_SHA TLS_DH_RSA_WITH_3DES_EDE_CBC_SHA TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SH A* TLS_DHE_DSS_WITH_DES_CBC_SHA TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SH A* TLS_DHE_RSA_WITH_DES_CBC_SHA TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA TLS_DH_anon_EXPORT_WITH_RC4_40_MD5* TLS_DH_anon_WITH_RC4_128_MD5 TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA TLS_DH_anon_WITH_DES_CBC_SHA TLS_DH_anon_WITH_3DES_EDE_CBC_SHA LHC Grid Computing School

LHC Grid Computing School Client Server Certificate Chain: client cert. CA cert. root CA cert. EncryptedPreMasterSecret(EKUS[pre_master_secret]) ClientDiffieHellman Public Value EKRC[H(handshake_messages)] 이전에 교환된 모든 핸드쉐이크 메시지(Change Cipher Spec 제외) change_cipher_spec EKclient_write_key[PRF(master_secret, “client finished”, MD5(HM) + SHA-1(HM))] change_cipher_spec EKserver_write_key[PRF(master_secret, “server finished”, MD5(HM) + SHA-1(HM))] LHC Grid Computing School

LHC Grid Computing School 레코드 프로토콜 어플리케이션 데이터 가나다 라마바 사아자 가나다라마바사아자 1. 단편화 3. MAC 생성 4. 암호화 5. TLS 헤더 생성 2. 압축 LHC Grid Computing School

단편화 압축 MAC 생성 레코드 페이로드 생성 214 바이트로 단편화 SSL 3.0/TLS 1.0에서는 지원하지 않음 HMAC_hash(MAC_write_secret, seq_num + TLSCompressed.type + TLSCompressed.version + TLSCompressed.length + TLSCompressed.fragment) Content Type(1) Major Version(1) Minor Version(1) Compress Length(2 bytes) 암호화 데이터 LHC Grid Computing School

Cryptographic Computation Master Secret(48byte) 계산 master_secret = PRF(pre_master_secret, “master secret”, ClientHello.random + ServerHello.random) PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR P_SHA-1(S2, label + seed) P_hash(Secret, seed) = HMAC_hash(secret, A(1) + seed) + HMAC_hash(secret, A(2) + seed) + HMAC_hash(secret, A(3) + seed) + …… A(0) = seed A(i ) = HMAC_hash(secret, A(i-1)) LHC Grid Computing School

LHC Grid Computing School Key Block 생성: 필요한 길이만큼 생성 Key Block를 다음과 같이 분리해서 키를 생성 ex) IDEA_CBC_SHA key_block = PRF(SecurityParameters.master_secret, “key expansion”, SecurityParameters.server_random + SecurityParameters.client_random); 20bytes client_write_MAC_secret 20bytes server_write_MAC_secret 16bytes client_write_key 88bytes 16bytes server_write_key 8bytes client_write_IV 8bytes server_write_IV LHC Grid Computing School

LHC Grid Computing School 5. 결론 The Grid Security Infrastructure (GSI) is a set of tools, libraries and protocols used in Globus to allow users and applications to securely access resources. Based on a public key infrastructure, with certificate authorities and X509 certificates Uses SSL for authentication and message protection Adds features needed for Single-Sign on Proxy Credentials Delegation In the GSI system each user has a set of credentials they use to prove their identity on the grid Consists of a X509 certificate and private key Long-term private key is kept encrypted with a pass phrase Good for security, inconvenient for repeated usage Single-sign on is important feature for Grid Applications Enables easy coordination of multiple resources User authenticates themselves once, then can perform multiple actions without re-authentication Can allow processes to act on their behalf To support single sign-on GSI adds the following functionality to SSL: Proxy credentials Credential delegation LHC Grid Computing School

GSI in Action “Create Processes at A and B that Communicate & Access Files at C” Single sign-on via “grid-id” & generation of proxy cred. User Proxy User Proxy credential Or: retrieval of proxy cred. from online repository Remote process creation requests* Site A (Kerberos) GSI-enabled GRAM server Authorize Map to local id Create process Generate credentials Ditto GSI-enabled GRAM server Site B (Unix) Computer Computer Process Process Local id Communication* Local id Kerberos ticket Restricted proxy GSI-enabled FTP server Authorize Map to local id Access file Remote file access request* Restricted proxy Site C (Kerberos) * With mutual authentication Storage system LHC Grid Computing School

LHC Grid Computing School