Security 1: Introduction

ISSGC06, Ischia July 2006

Dr John WattGrid Security Engineer

National e-Science Centre University of Glasgow

[email protected]

10th July 2006

Security 1: Introduction


Introduction to Security (14.30-15.00)Security: Is it possible?FundamentalsA Question of Trust

Authentication (15.00-15.30)Who am I??Basic CryptographyPublic Key Infrastructures (PKIs)Certificates and AuthoritiesProxies and Temporary Credentials

Overview


Introduction to Security


Introduction to Security What do we mean by security anyway?

Secure from whom? From systems administrator? From rogue employee? Mr. H.

Acker…?

Secure against what? Denial of Service? Identity theft? Legally sensitive data acquisition?

– Or even MPs leaving laptops on the Tube…

Secure for how long? “I recommend overwriting a deleted file seven times: the first time

with all ones, the second time with all zeros, and five times with a cryptographically secure pseudo-random sequence. Recent developments at the National Institute of Standards and Technology with electron-tunnelling microscopes suggest even that might not be enough. Honestly, if your data is sufficiently valuable, assume that it is impossible to erase data completely off magnetic media. Burn or shred the media; it's cheaper to buy media new than to lose your secrets…."

» -Applied Cryptography 1996, page 229


Introduction to Security

Secure technology ≠ secure systemSystem using 2048+ bit encryption technology, packet filtering firewalls, PMIs, PKIs…

…. on running laptop in unlocked room … on PC with password on “post-it” on screen/desk We have heard worse than this, naming no names!

Famous quote to muse over: “…if you think that technology can solve your security

problems then you don’t know enough about the technology, and worse you don’t know what your problems are…”

» Bruce Schneier, Secrets and Lies in a Digital Networked World


Fundamentals

Key terms that are typically associated with security

AuthenticationAuthorisation Audit/accountingIntegrityFabric ManagementConfidentiality Privacy Trust

All are important for Grids but some applications may have more emphasis on certain concepts

than others


Fundamentals - Authentication

• Authentication • the establishment and safe propagation of a

user’s identity in the system• e.g. so site X can check that user Y is attempting to gain access to

resources• Note does not check what user is allowed to do, only that we

know (and can check!) who they are• Masquerading always a danger (and realistic possibility)• Need for user guidance on security

• Password selection• Treatment of certificates• Hardware tokens• …

• Is anonymity required?

• Authentication on the Grid is achieved with Public Key Infrastructures (PKIs)


Fundamentals - Authorisation

Authorisationconcerned with controlling access to services based on policy

Can this user invoke this service making use of this data? Complementary to authentication

– Know it is this user, now can we restrict/enforce what they can/cannot do

Many different contenders for authorisation infrastructures

PERMIS VOMS CAS AKENTI

Authorisation on the Grid must be scalable.


Fundamentals - Auditing

Auditing/Accountingthe analysis of records of account (e.g. security event logs) to investigate security events, procedures or the records themselves

Includes logging, intrusion detection and auditing of security in managed computer facilities

– well established in theory and practice» Grid computing adds the complication that some of the

information required by a local audit system may be distributed elsewhere, or may be obscured by layers of indirection

» e.g. Grid service making use of federated data resource where data kept and managed remotely

Need tools to support diagnostics– Do we need to log all information? (Can We? More pertinent

probably)– How long do we keep it for?– …

Auditing tools are in development for some authorisation infrastructures

PERMIS Secure Audit System


Fundamentals - Integrity

IntegrityEnsuring that data is not modified since it was created, typically of relevance when data is sent over public network

Technical solutions exist to maintain the integrity of data in transit

– checksums, PKI support, … Grid also raises more general questions

– e.g. provenance» maintaining the integrity of chains or groups of related

data

Integrity can be checked through the use of digital signatures


Fundamentals - Fabric Management

Fabric Managementconsists of the distributed computing, network resources and associated connections that support Grid applications

impacts Grid security in these ways: – an insecure fabric may undermine the security of the Grid

» Are all sites fully patched (middleware/OS)?

– Can we limit damage of virus infected machine across Grid?» Identify it, quarantine it, anti-virus update/patch, re-instate

into VO, …

– fabric security measures may impede grid operations » e.g. firewalls may be configured to block essential Grid traffic


Fundamentals - Confidentiality

Confidentiality

is concerned with ensuring that information is not made available to unauthorised individuals, services or processes

It is usually supported by access control within systems, and encryption between systems

– Confidentiality is generally well understood, but the Grid introduces the new problem of transferring or signalling the intended protection policy when data staged between systems

– Authentication and Authorisation infrastructures usually implement confidentiality, so we are already there!


Fundamentals - Privacy

Privacy particularly significant for projects processing personal information, or subject to ethical restrictions

e.g. projects dealing with medical, health data

Privacy requirements relate to the use of data, in the context of consent established by the data owner

Privacy is therefore distinct from confidentiality, although it may be supported by confidentiality mechanisms.

Grid technology needs a transferable understanding of suitable policies addressing privacy requirements/constraints

– Should allow to express how such policies can be » defined, » applied, » implemented, » enforced, …


TrustTrust

characteristic allowing one entity to assume that a second entity will behave exactly as the first entity expects

Important distinction between ‘trust management’ systems which implement authorisation, and the wider requirements of trust

e.g. health applications require the agreement between users and resources providers of restrictions that cannot be implemented by access control

– e.g. restrictions on the export of software, or a guarantee that personal data is deleted after use

therefore a need to understand and represent policy agreements between groups of users and resource providers

– such policies may exist inside or outside the system, and are typically not supported by technical mechanisms


Trust

Key concept for Grid securityOverall Grid security policy is impossibleSites must integrate local security policies to create Virtual Organisations

Essential to have mechanisms which allow trust to be established between participating institutions

Security Policies should:Be kept and managed by the local site

The Grid should aim to integrate existing site policies rather than centralise them.

A ‘Federation’ of trusted sites for VOs– Shibboleth??


Authentication


Who Am I??

I amThe President of the United States

The Secretary General of the United Nations

David Beckham

Keith Richards

The girl who served your cup of coffee this morning..

All of these people may need to use a computer

How can we confirm their identities?


Who am I??

I am John Watt (allegedly)To prove it I have

A Driving Licence– I got by passing my test and producing my

passport

A Passport– I went to the passport office with my Birth

certificate

A Birth Certificate– I can’t remember getting this!


Who am I??

Is there a logical chain working here?Note that, generally, the credentials given on the previous page tend to depend on the one below it.

But the DVLA (UK Driving Licence Authority) state on their website:

– “Note - Birth certificates are not absolute proof of identity and so we may ask you to provide other evidence to allow us to check your identity.”

– What other evidence? A passport?» But that depends on you producing a birth certificate!

– A bank account?» You need a passport for that!

NO!


Who am I??

But they do have one thing in commonThey are non-local credentials

They attempt to define a unique (nationally at least) reference that will establish your identity

Do we need something similar for the Grid??

First of all, we need to establish how identity can be proved and securely moved around a network.The Grid community are (in principle) in agreement about how this should be done

But first we need to look at the basics of this system, and it has to do with an age old problem…


Basic Cryptography

When I were a lad…My friend would post an important message through my letterbox…

But we had ‘code wheels’ Rotate the inner wheel by the

number of jumps indicated at the beginning of the message

And translate…3 Y O U S M E L L

3 V L R P J B I I


Basic Cryptography

What if someone else got hold of the wheel?

Our plans for world domination are in ruinsBecause what makes the wheel work is the extra information included with the original encrypted message:

Without this number the message will stay encryptedThis number is the encryption ‘key’

And is transmitted UNENCRYPTED– We could agree this face-to-face, but why not just give the

message then?? What if I was grounded? (happened a lot) Lets look at this at a slightly more mature level…

3 V L R P J B I I


Basic Cryptography

The above scenario describes a SYMMETRIC key system

Same key is required for encryption and decryptionBut this key CANNOT be transmitted without compromising both sides’ messages.

AA BBdecrypt

encryptdecrypt

encrypt


Basic Cryptography

We need some way of transmitting the key so it can’t be stolen.

Can we encrypt the key? No, but we can do something analogous…

1) Split the key into two parts, one for encryption and one for decryption.

2) Make the encryption key PUBLIC for anyone to use, but keep your decryption key PRIVATE.

Note that in some implementations the private key may also be used to encrypt and the public key to decrypt (see Digital Signatures)


Basic Cryptography

We have solved the key transmission problem by only transmitting an encryption key

Now anyone who wishes to send you a message uses your PUBLIC key to encrypt it, safe in the knowledge that the only person who can decrypt it is the holder of the PRIVATE key (i.e. you!)

The public and private keys are broken apart according to a complex mathematical formula that means it would take months/years to crack messages without the private key.

Tends to outlive credentials issued (e.g. credit cards)


Basic Cryptography

This is ASYMMETRIC encryptionPublic key is available for B to write messages to AOnly A can read them as they hold the Private key.

BBReceive key

encryptreceive

Publish key

publicdecryptprivate

A


Basic Cryptography

Symmetric encryption only guarantees privacy

The message is still encrypted, but there is no evidence of who encrypted it, nor any guarantee the data has not been tampered with.

Asymmetric encryption can be used to authenticate

By encrypting a message with someone’s private key, you can be sure ONLY they will be able to read it.

And…Some level of integrity may be provided (digital signatures)


Public Key Infrastructures (PKIs)

PKIs provide a mechanism for privacy, integrity and authentication using public keys

Implemented with DIGITAL CERTIFICATES Your UNIQUE virtualised identity

Issued by a CERTIFICATE AUTHORITY Entity which administers certificates and issues them correctly

X509 (1988) is the standard for PKI certificates Binds a globally unique X500 distinguished name to a public key

– In reality, CAs tend to choose any name they want» Legal disclaimer, liability transfer. A mess, but not critical

Web browser compatible


Public Key Infrastructures (PKIs)

For our purposes (Grid), an X509 certificate contains the following primary information:

The CAThe SubjectThe Public KeyA Digital Signature

+ validity, version, algorithms

Certificate: Data: Version: 1 (0x0) Serial Number: 6 (0x6) Signature Algorithm: md5WithRSAEncryption Issuer: C=gb, O=glasgow, OU=admin, CN=soa Validity Not Before: Jun 1 13:38:45 2006 GMT Not After : Jul 10 13:38:45 2010 GMT Subject: C=gb, O=glasgow, OU=dcs, CN=anthony Subject Public Key Info: Public Key Algorithm: rsaEncryption RSA Public Key: (1024 bit) Modulus (1024 bit): 00:df:f7:e6:f3:3c:69:da:62:ba:d3:bf:e8:1a:9c: 3d:2e:8b:a5:51:21:6e:f0:8a:66:c8:1e:0b:70:95: 0e:f3:c7:78:63:e0:fc:bc:06:dd:42:fc:cd:c3:11: ec:f6:b6:b2:be:2e:09:35:aa:35:ad:ae:39:b0:ea: 04:93:51:1e:85:96:40:26:b8:42:dd:ba:a7:56:eb: c5:69:a6:b9:ff:5d:0d:f0:88:93:bd:6e:a4:2c:b2: ae:2d:f0:70:73:7e:b5:01:21:b5:e2:5b:89:2a:e3: 0f:a0:1f:95:71:31:cd:43:a2:16:57:d6:94:e2:e9: 72:c5:8c:21:83:3a:31:c4:85 Exponent: 65537 (0x10001) Signature Algorithm: md5WithRSAEncryption 8f:74:21:08:db:fa:e4:af:4e:d5:46:90:ad:0f:1e:8f:97:09: 52:eb:f6:f5:c3:4e:bc:07:68:c7:4f:fe:1c:ab:f5:76:3f:ed: 2b:62:81:6f:2c:ad:78:a4:06:7e:4b:7a:96:4b:17:96:5d:db: 34:b3:fe:5b:72:85:0d:32:f2:78:2a:20:32:43:87:2d:0c:70: 96:a8:5f:63:82:cb:3e:c0:5f:9a:2e:bb:50:dd:79:b8:2a:d0: a4:32:6c:e6:b3:72:ab:31:70:16:52:f3:85:20:98:58:38:f1: 6a:b1:c1:0c:81:83:f4:70:f1:2b:fb:0d:93:ae:35:8a:32:56:


Certificate Authorities

A Certificate Authority (CA) is a third party that signs certificates and ensures that the subject name and public key actually belong to that person

How? The old fashioned way… Example… The UK e-Science Certificate Authority

– Initial contact – application (online)– Credential verification (IN PERSON)

» Go to CA or Regional Authority (RA)

– Issue – download (online)» UK CA requires the application and issuing terminals to be the

same ( this is where the PRIVATE key of your certificate is)



A CA may delegate Regional Operators to confirm people’s identities

Saves me having to travel from Glasgow to Oxford if I want a certificate

CA records a piece of personal identification for their records

Passport, Driving Licence, Staff/Student Matric Card

CA extends an existing ID infrastructure – good thing



A CA also is in charge of revoking certificates

CA publishes a Certificate Revocation List Download to your browser Shows all invalid certificates in the organisation

A CA MUST be explicitly trusted by the system

Trusted Root CAs list in WindowsCertificate cannot be used until the CA’s root certificate has been accepted as trusted

Accepted very much like Software Licences i.e. nearly always!


Digital Signatures

CAs confirm the certificate’s authenticity by digitally signing it

CA computes a hash of the certificate using an agreed (non-secret) algorithmCA encrypts this hash with their private key and appends to bottom of certificateRecipient computes their own hash of the infoRecipient decrypts the hash the CA sent (with the CA’s public key) and compares with their own

Proves the CA signed the info and the info hasn’t been tampered with

– Encryption of the info is optional (for privacy)


A problem

Are there any pitfalls to digital certificates?

Can we alter their contents? No, the CA signed the certificate thus ensuring its integrity

Can we spoof? You will need your own CA, and if the application doesn’t trust

it, your certificates won’t work. So no.

What can we do? STEAL IT!

– Someone who holds your digital certificate (and private key) may safely assume your identity on the Grid

– This problem isn’t going away. How can we deal with this?


Proxies

Temporary credentialsIf the certificate is that sensitive, we shouldn’t fire it off across the Grid where you will lose track of it.Instead create a PROXY CERTIFICATE

A proxy certificate is a new version of your certificate, but this time with your original certificate as the CA

It has a VERY SHORT lifetime– So if it is stolen, it can only be used for a short time (24

hrs)– Revocation is unnecessary as it expires so quickly

» You don’t need to revoke the ORIGINAL certificate as it was only the proxy (which is different) which was stolen

Proxy certificates have another feature which becomes obvious when you actually look at what a proxy looks like…


Proxies

A proxy certificate seems to be 3 certificates in one!

Not so, the proxy certificate is only the first certificateThe second is the private key of the proxyThe third is the original certificate the proxy was made from

Why??

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE----------BEGIN RSA PRIVATE KEY-----MIIBOgIBAAJBAJZTXbA8nMe/nTRHMVif1sD9pxGbVmg0qzOm6bTZwKHK8OHnxdF90D65UGE8e/G52pm038YdoprP/b/6PfCZuxECAwEAAQJAGD9MLmAofcO3jLYrDHuDvU9swldHAbn1H3i927D/9FizZqpkEe+KhD59+gE91eL8mw6xagj3vkTi6HS0Ff3E0QIhAMV5ZrSFczh1VAyVDkXyQxvR5qgPCp5GJwO/Psamo8jFAiEAwuC/YoN75Ox2PFnSVbHy60pm0rAEkIrkLu7xKqYcVd0CIFjsultAXQpni1m/JZZJ6f51HzE+1MFBRgBh9pruH4MhAiEAtsyhWeRiPCu/AP90eKQSbLl+2BT6Qye1wXyrRklI/RUCID5+RNLI8mR2xUx4HRyW/RcJDLaDtBAr0NO7gPUvdYd3-----END RSA PRIVATE KEY----------BEGIN CERTIFICATE-----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-----END CERTIFICATE-----


Proxies

Proxies propagate through the grid by signing new versions of themselves

Using the proxy certificate and its private key, any number of new proxies may be spawned across each required resource.

Acheives two goals DELEGATION

– Proxy acts on your behalf SINGLE SIGN-ON

– You only need to logon to the Grid once


Summary

Security is a combination of technical implementation and sociological behaviour

There can be no overall security policy for the Grid – integrate existing site policies

The establishment of identity on the Grid (authentication) is achieved through the use of PKI Certificates and Proxies

Security 1: Introduction

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