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SSL Trust Pitfalls
Prof. Ravi Sandhu
2© Ravi Sandhu
SERVER-SIDE SSL (OR 1-WAY) HANDSHAKE WITH RSA
Client Server ClientHello --------> ServerHello Certificate <-------- ServerHelloDone ClientKeyExchange [ChangeCipherSpec] Finished --------> [ChangeCipherSpec] <-------- Finished Application Data <-------> Application Data
RecordProtocol
HandshakeProtocol
3© Ravi Sandhu
CLIENT-SIDE SSL (OR 2-WAY) HANDSHAKE WITH RSA
Client Server ClientHello --------> ServerHello Certificate CertificateRequest <-------- ServerHelloDone Certificate ClientKeyExchange CertificateVerify [ChangeCipherSpec] Finished --------> [ChangeCipherSpec] <-------- Finished Application Data <-------> Application Data
RecordProtocol
HandshakeProtocol
4© Ravi Sandhu
SINGLE ROOT CA MODEL
RootCA
a b c d e f g h i j k l m n o p
RootCAUser
5© Ravi Sandhu
SINGLE ROOT CAMULTIPLE RA’s MODEL
RootCA
a b c d e f g h i j k l m n o p
RootCA
User RA
User RA
User RA
6© Ravi Sandhu
MULTIPLE ROOT CA’s MODEL
RootCA
a b c d e f g h i j k l m n o p
RootCAUser
RootCA
RootCA
RootCAUser
RootCAUser
7© Ravi Sandhu
ROOT CA PLUS INTERMEDIATE CA’s MODEL
Z
X
Q
A
Y
R S T
C E G I K M O
a b c d e f g h i j k l m n o p
8© Ravi Sandhu
MULTIPLE ROOT CA’s PLUS INTERMEDIATE CA’s MODEL
X
Q
A
R
S T
C E G I K M O
a b c d e f g h i j k l m n o p
9© Ravi Sandhu
MULTIPLE ROOT CA’s PLUS INTERMEDIATE CA’s MODEL
X
Q
A
R
S T
C E G I K M O
a b c d e f g h i j k l m n o p
10© Ravi Sandhu
MULTIPLE ROOT CA’s PLUS INTERMEDIATE CA’s MODEL
X
Q
A
R
S T
C E G I K M O
a b c d e f g h i j k l m n o p
11© Ravi Sandhu
MULTIPLE ROOT CA’s PLUS INTERMEDIATE CA’s MODEL
Essentially the model on the web today
Deployed in server-side SSL mode Client-side SSL mode yet to happen
12© Ravi Sandhu
SERVER-SIDE SSL (OR 1-WAY) HANDSHAKE WITH RSA
Client Server ClientHello --------> ServerHello Certificate <-------- ServerHelloDone ClientKeyExchange [ChangeCipherSpec] Finished --------> [ChangeCipherSpec] <-------- Finished Application Data <-------> Application Data
RecordProtocol
HandshakeProtocol
13© Ravi Sandhu
SERVER-SIDE MASQUARADING
BobWeb browser
www.host.comWeb serverServer-side SSL
UltratrustSecurityServices
www.host.com
14© Ravi Sandhu
SERVER-SIDE MASQUARADING
BobWeb browser
www.host.comWeb server
Server-side SSL UltratrustSecurityServices
www.host.comMallory’sWeb server
BIMMCorporation
www.host.com
Server-side SSL
15© Ravi Sandhu
SERVER-SIDE MASQUARADING
BobWeb browser
www.host.comWeb server
Server-side SSL UltratrustSecurityServices
www.host.comMallory’sWeb server
Server-side SSL
BIMMCorporation
UltratrustSecurityServices
www.host.com
16© Ravi Sandhu
CLIENT-SIDE SSL (OR 2-WAY) HANDSHAKE WITH RSA
Client Server ClientHello --------> ServerHello Certificate CertificateRequest <-------- ServerHelloDone Certificate ClientKeyExchange CertificateVerify [ChangeCipherSpec] Finished --------> [ChangeCipherSpec] <-------- Finished Application Data <-------> Application Data
RecordProtocol
HandshakeProtocol
17© Ravi Sandhu
MAN IN THE MIDDLEMASQUARADING PREVENTED
BobWeb browser
www.host.comWeb server
Client-side SSL
UltratrustSecurityServices
www.host.com
Mallory’sWeb server
BIMMCorporation
Client-side SSL
UltratrustSecurityServices
www.host.com
Client Side SSLend-to-endUltratrust
SecurityServices
Bob
BIMMCorporation
UltratrustSecurityServices
Bob
18© Ravi Sandhu
ATTRIBUTE-BASED CLIENT SIDE MASQUARADING
Joe@anywhereWeb browser
BIMM.comWeb serverClient-side SSL
UltratrustSecurityServices
BIMM.com
UltratrustSecurityServices
Joe@anywhere
19© Ravi Sandhu
ATTRIBUTE-BASED CLIENT SIDE MASQUARADING
Alice@SRPCWeb browser
BIMM.comWeb serverClient-side SSL
UltratrustSecurityServices
BIMM.com
SRPC
Alice@SRPC
20© Ravi Sandhu
ATTRIBUTE-BASED CLIENT SIDE MASQUARADING
Bob@PPCWeb browser
BIMM.comWeb serverClient-side SSL
UltratrustSecurityServices
BIMM.com
PPC
Bob@PPC
21© Ravi Sandhu
ATTRIBUTE-BASED CLIENT SIDE MASQUARADING
Alice@SRPCWeb browser
BIMM.comWeb serverClient-side SSL
UltratrustSecurityServices
BIMM.com
SRPC
PPC
Bob@PPC
22© Ravi Sandhu
PKI AND TRUST
Got to be very careful Not a game for amateurs Not many professionals as yet
