WS-Security Protocol

Ramkumar ChandrasekharanCS 265

Web Services (WS) A service available over Internet Standard protocols: HTTP, SMTP, FTP Is based on XML messaging

systemSOAP (Simple Object Access Protocol), XML-RPC A WS should be self describingWSDL: Web Services Description Language DiscoverableUDDI: Universal Description Definition Interface

Consuming a Web Service1) Client discovers the WS from UDDI

registry to which WS has published itself2) Client retrieves the WSDL file pointed by

UDDI3) Client Creates SOAP packets with the

appropriate Web Service calls4) Invokes Web Service method over HTTP,

SMTP etc5) Response is received from the WS as a

SOAP packet as well

WS is not secure XML messages over the network. Anybody

can easily sniff and read the text. Secure with SSL at transport layer but

does not guarantee end to end security. SSL also encrypts everything which could be resource expensive.

Many ways of securing at message layer for WS is possible, WS-Security is a standard way of securing WS.

WS-Security WS-* SpecsStandardizing various pieces of Web Service for

e.g., Security, Policy, Messaging etc. Various Standards Orgs (OASIS,

W3C etc.) and corporations (IBM, MS, Verisign etc.) are involved

WS-Security SOAP header carries security info XML Encryption standard is used

for encryption XML Signature standard is used for

Digital Signature

SOAP Security Header<soap:Envelopexmlns:soap=

http://schemas.xmlsoap.ord/soap/envelopexmlns:wsse=”http://schemas.xmlsoap.ord/ws/

2002/12/secext”><soap:Header><wsse:Security soap:role=”….”>All the security related mechanisms like security

tokens, encryption and signatures goes here</wsse:Security>

WS-Security Tokens Authentication mechanisms: UsernameTokenPlaintext, Hashed (Base64 Encoding (SHA-1 (Nonce +

Created + Password))

Binarysecuritytoken based on Kerberos or X.509 certificates

XML Encryption Provides End to end security Selective Encryption Very simple to do, lets say if there

is an XML doc for e.g.,

XML Encryption XML before

encryption:<?xml version=‘1.0’?><CreditCard><Name>John </Name><Number> 1234567</Number><Code>123</Code><Expiry>0106</expiry></CreditCard>

XML After encryption

<?xml version=‘1.0’?><CreditCard><Name>John </Name><EncryptionData>

<CipherData><CipherValue>

asdgsd45454</CipherValue>

</CipherData></EncryptionData></CreditCard

XML Signature Standard Schema for digital

signature XML docs Selective Signing of XML docs, that

is portions of XML docs can be signed

Its not as simple as XML encryption

XML Signature Schema <Signature>

<SignedInfo><CanonicalizationMethod /><SignatureMethod /><Reference URI=“ “> (0 or more)<Transforms/><DigestMethod/><DigestValue/></Reference></SignedInfo><SignatureValue /> - Digest of SignedInfo<KeyInfo/> (Optional)

</Signature>

WS-Security Demo

Using WSE 2.0

Conclusion Web service is going to create revolution in

distributed computing and with standards like WS-Security helps achieve security into Web Services.

With Web Services the vision of Vint Clif “father of the Internet’ could be achieved. He said “it wont be long before your bathroom scale surreptitiously transmits your weight to your doctor, who might command a stop to the rocky road ice cream your fridge automatically orders for you from www.groceries.com”.

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