476 REVISION SUMMARY BY Alex Peng
Definition of key concepts (paper1+handout) ------------------------------------------ Information Security:
o (Anderson 2003): A well-informed sense of assurance that information
risks and controls are in balance.
o (Solms 1999): The aim of information security is to ensure business
continuity and minimise business damage by preventing and minimising
the impact of security incidences.
o (Solms 1999, why important): The CIA of business information may be
essential to maintain the competitive edge, cash-flow, profitability, legal
compliance and respected company profile; information security threats
become more widespread and increasingly sophisticated; the growth of
network presents new opportunities for unauthorized access of business
data.
 Standards (Eloff and Solms 2000):
International Standards: documented agreements containing exact criteria that
must be followed consistently as rules, guidelines or definitions of
characteristics to ensure that any materials, products, processes or services are
fit for their purpose.
National standards: (N/A but should be the same as international version. Just
considering BS7799-1ISO17799)
Organizational standards: a specific rules and requirements adopted in or
prescribed for the company internally.
Impact of standards (handout):
 Enhance compatibility or interoperability
 Reduced uncertainty
 Reduced consumer lock-in
 Competition for the market vs. competition in the market
 Competition on price vs. features
 Certification (Handout):
the issue of a formal statement (certificate) confirming the results of the
security evaluation.
 Accreditation (Handout):
the procedure for accepting a product, a service, a system for use within a
particular environment.
 Evaluation (Handout):
476 REVISION SUMMARY BY Alex Peng
assessment of a product or service against defined security evaluation
criteria/standards 注意：评估是需要依据的。这里的依据就是那些安全标
准如 BS7799.
SECURITY in e-commerce------------------------------------------------------------------ How to prevent information?
Information can be altered (integrity) or corrupted (availability) or misused
(confidentiality) in any phase of the information life cycle:
Creation/store/process/transmit/used/lost/corrupted/destroyed
1. Structure:
(Stephen Wilson 1997+Handout of cryptosystems)
Integrity: The assurance to an entity that data has not been altered (intentionally or
unintentionally) between “there” and “here”, or between “then” and “now”.
 Cryptography security: PKC (public key cryptography)
o Two properties of a successful encryption algorithm:
 You need the right key to decrypt an encrypted message
 Any change to an encrypted message will also cause the
decryption to fail
 These properties can be exploited to provide “CIANA”.
Authentication: The assurance to one entity that another entity is who/he/she/it
claims to be.
 Digital signature
o The relationship between public key and private key: mathematical “one
way function” (Hash algorithm, for example)---it is computationally
infeasible for a private key to derive from the knowledge of public key.
o Signature: Hash algorithm  encrypted by originator’s private key .
o Verify: public key to reverse the encryption processre-compute the
hash
Non-repudiation: The inability of the originator to deny later having sent the letter.
 Digital signature
Confidentiality: The assurance to an entity that no one can read a particular piece of
data except the receiver(s) explicitly intended.
476 REVISION SUMMARY BY Alex Peng
 Cryptography security + key escrow (copies of keys would be lodged either
with the government or with trusted third parties.) (PKICA…)
 To make a message secret, the original message can be encrypted under a
DIFFERENT cryptographic key, AFTER digital signature.
 Notice that key escrow and key recovery proposals only apply to
confidentiality tools.
2. Public Keys Infrastructure (PKI) (instance: PKAF)
(Handout from ADMIS 2006-2007. Feel free to contact me if u need this ppt.)
Definition of PKI:
“The set of hardware, software, people and procedures needed to create, manage,
store, distribute and revoke certificates based on public-key cryptography” X.509
Definitions of interoperability:
 “Interoperability means the ability of information and communication
technology systems and of the business processes they support to
exchange data and to enable the sharing of information and knowledge”
IDA
 “Interoperability means the co-operation of systems, processes and
people, in order to deliver seamless and customer-centric services. It
encompasses three different aspects: Technical, Semantic,
Organisational” IDABC
PKI elements:
• Policy Authority
• Certificate Authority (CA) ( or Trust Services Provider)
• Registration Authority (RA)
• Subscribers
• Relying Parties
• Repositories
The interoperability of PKIs globally:
(Backhouse, et al 2003)
Considerable effort on both technical and policy fronts has been expended to address
these five security matters in e-commerce. Public key cryptography is gradually
emerging as the prime technology for providing very secure authentication of identity
online with the use of a Certification Authority as trust intermediary.
Problem domain:
At the moment most CAs are highly localized in their marketplace and operate
largely within the confines of a single territory, jurisdiction and language. Equally the
electronic communities they support with their trusted services are, in global terms
476 REVISION SUMMARY BY Alex Peng
still parochial in nature. To achieve e-commerce on a global scale, PKIs must be able
to interoperate so that the digital certificates issued in one domain are accepted in a
foreign domain. Furthermore, both technical and institutional problems of PKI
interoperability must be resolved.
Existing approaches for resolving this problem: cross-certification, cross-recognition
and Bridge CA.
Alternative approach suggested by Backhouse: the problem of interoperability in PKI
can be solved by the use of accreditation schemes in concert with international
standards
Lessons from the failure study of c:cure + BS7799:
 Market-led Leadership
 Legislation in Place
 Government Sets the Example
 Efficient Auditor Assessment Process
Certificate Authority Architecture:
(Liddy and Strugeon 1999)
General trend: Architectures such as hierarchical, cross-certificated CAs will become
more frequently used, as the complexity of business use increases and risk of
exposure increases.
The evolution of internet: IntranetsExtranetsGlobalnet
Current models of CA:
 The critical issues driving the evolution of CA models architecture:
 Technology models
 Marketplace or customer maturity
 Geopolitical concerns
 Each models has been developed based on different business requirements.
 The architectures are different particularly in the cryptographic generation of
CA keys.
 CA products=key generation + key management systems + key architectures +
use of key structures + standard (X509.v3)
Proprietary model (私有模型)
 Offering for various Virtual Private Networks (VPNs)
 Often a part of browser based software
 Support SET and SSL
 Security provided by proprietary and non-standards-based solutions for
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specific closed system in organizationsused within organizations thus
support intranet ONLY.
 Pros: Restrict access
 Cons:
o cannot be easily evaluated against standards
o difficult to migrate to extranet use (redesign needed)
Self-signed CA
 Security is based on acceptance of users of the central server as being
trusted without necessarily the appropriate system security controls and
mechanisms
 Pros: relatively cheap
 Used for low confidentiality and authentication requirements (kind of
willing to face risk)
 The cheapest version running on Microsoft browsers is ubiquitous
 Cons:
o cannot be easily evaluated against standards
 Structure (see paper)
 Suitable for (see paper)\
TTP (trust third party)
 The ideal model for global internet; Open systems architecture
 Developing international standards
 Trust is ensured by a third party that is subject to and abide by exhaustive
means and measures of delivering secured transactions.
 Two architecture:
o Centralized structure
 A central CA sign both user certificates and registration
authority (RA) certificates
 RA provide the user verification
 Potential users can apply either RA or directly to central CA for
their certificate.
 Drawback: the conflict the CA has with geopolitical elements(
CA complies with only one central government authority)
o Hierarchical structure
 Through a hierarchical structure of “signed roots”, each CA can
issue a certificate and make it recognized by other CAs in this
network.
 Center of root: policy creation authority (PCA, 政策起草) and
policy approval authority (PAA, 政策批准)
 Pros: can issue a certificate on a decentralized basis. This may
be important when a national CA wishes to provide seamless
international transactions but must at the same time adhere to
national legislation or regulation pertaining to certificate
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issuance and management.
Factors to consider in choosing a model
Keying structure: based on cryptographic requirements and confidentiality sought
Certificate technologies: based on authentication requirements and include criteria
such as the size and nature of the groups in the CA community
Role of marketplace:
 The major obstacle to the growth and acceptance of global electronic business
is the absence of standards to enforce common recognition and confidence in
the security of transactions.
 The market will serve to force the adoption of standards and their
implementation. The principle issue is cross certification.
 Cross-Certification: currently multiple PKIs independently implemented
and operated, serving different environments and user communities,
whilst inevitably some of them need to be interconnected. Changing
business relationships or other reasons will necessitate secure
communication was not previously a requirement. In the absence of single
global PKI, corss-certification is the accepted mechanism for enabling
users of one PKI community to validate the certificates of users in another
PKI community.
 Cross-certification of TTPs:
 Involves the root certification authority accepting the other TTPs’
security policy and practices.
 As the keys and certificates are ubiquitous, one technology component
needs to be cross-certified is the set of certificate revocation lists.
 Cross-certification of proprietary systems
 Involves setting up both policy and technology between two
organizations. The policy must denote what levels of security are
acceptable for both, and it must address agreement on compliance
audit.
 This must be repeated for each organization wishing to cross-certify with
any other organization.
 Notice: the more times the systems cross-certify the greater the chances
the system will break down, as the linkages between the systems will
allow for an unsecured passage of both keys and certificates if one
organisation deviates from the accepted policy.
 Cross-certification provides that essential next step towards the future of
certification and cryptography products on the Internet. But how? 
 International standards for technology must be formalized and recognized.
 Vendors must develop products and services adhering to these standards.
476 REVISION SUMMARY BY Alex Peng
 The necessary policy and procedures to accompany secure solutions must
be developed and formally accepted as part of standards.
 National legislative and regulatory frameworks need to be developed such
that they set acceptable and achievable accreditation schemes.
3. Pitfalls in cryptographic design (把它和 E-BUSINESS 结合起来思考;找出哪
些和 E-BUSINESS 有关)
(Bruce Schneier 1998)
Intro. Strong Cryptography =/ Algorithm + Key length
 Longer keys do not always means more security. If the key is too long (tem
pins password for example), hackers will try cryptographic attack against the
algorithm.
 Strong cryptography does not means more security too. Smart hackers can go
around the algorithms. We can always find attacks bypass the algorithms
altogether. Hackers don’t try to match the keys, or break the algorithm, yet
they try to find the errors in the system design, installation and implementation.
1. Attacks against cryptographic designs
 The elements of a cryptosystem:
o Encryption algorithms
o Digital signature algorithms
o One-way hash functions
o Message authentication codes
 Break one, break whole; further more, if the structure is weak, a weak system
can probably be built with strong algorithms and protocols.
 Encryption algorithms don’t provide data integrity. While key exchange
protocols don’t necessarily ensure both parties receive the same key.
 Even good engineers or well-known organizations can not guarantee the robust
implementation.
 Random-number generators can be broken since it is possible to generate weak
keys even with strong encryption algorithms.
2. Attacks against implementations
 The involvement of human
 Some systems don’t ensure the plaintext is destroyed
 Sometimes same data be encrypted twice, one in strong keys whilst another
in weak keys.
 Some systems use inadequate protection mechanisms for the master keys
and mistakenly relying on the session keys.
 Account reconciliation flood attack
 Hotlist
 Keys recovery databases
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3. Attacks against keys
 System rely on user-generated passwords
4. Attacks against hardware
 Tamper-resistant hardware in commerce systems
 Timing attack
5. Attacks against trust models
 Attacks against the underlying trust model of system: who or what in the
system is trusted, in what way, and to what extent.
 Simple systems have simple trust models and complex systems have more
sophisticated models. The more complex, the more vulnerability is in the
system.
 Many software systems make poor trust assumptions about the computers
on which they run
 The cryptography may be irrelevant if it can be circumvented through
network insecurity, and no software is secure against reverse-engineering
 A system will be designed with one trust model in mind while implemented
in another.
6. Attacks against the users
 Users can subvert its security by accident; for example, a user give his/her
password to his co-workers.
 Good system design can not sole all these social problems.
7. Attacks against failure recovery
 Many systems have a “default to insecure mode”. A “version rollback
attack” against a system after it has been revised to fix a security problem:
the need for backwards compatibility allows an attacker to force the
protocol into an older, insecure version.
8. Attacks against the cryptography
 Proprietary cryptographic algorithms are particularly weak
 Keeping the algorithm secret is not much of an impediment to analysis—it
only takes couple of days to reverse-engineer the cryptographic algorithm
from the executable code.
Suggestion from Author:
 Preventing is essential for cryptographic systems, while detecting abuse is also
important.
 One design principle: no perfect design—sooner or later every system will be
successfully attacked.
476 REVISION SUMMARY BY Alex Peng
 Once the attack is detected, the system needs to recover, generate and
promulgate a new key pair, update the protocol and invalidate the old one,
remove an untrusted node from the system, etc.
Standards---------------------------------------------------------------------------------------1. TCSEC, ITSEC:
(Solms, 1999)
Three factors during technical evaluation process:
 Functionality
 Assurance of correctness
 Assurance of effectiveness
TCSEC: Trusted Computer Security Evaluation Criteria---the orange book
 Only evaluates technical features of products that can be bought
“off the shelf”, such as Windows XP, UNIX.
 Consider all the three factors together.
ITSEC: Information Technology Security Evaluation Criteria---the white book
 Evaluate the products as well as the systems
 Handle functionality independently and assurance of correctness and assurance
of effectiveness together.
2. BS7799:
(Eloff and Solms 2000)
BS7799 part1: Code of Practice for ISM
 Code of practice: Documents recording actions or practices which have led to
positive results in the past experiences.
 Constitutes a comprehensive reference document for identifying the range of IS
controls needed in most industry and commerce scenarios.
 Contains detailed set of controls that will meet the IS requirements of the majority
of organizations across all functional domains.
 A guide and recommendation document for management members who are
responsible for initiating, implementing and maintaining IS.
 10 sections (refer to BS7799 part 1)
 A risk management strategy is recommended by means of which to identify the
critical factors for successful implementation and maintenance of IS measures.
476 REVISION SUMMARY BY Alex Peng
BS7799 part2: Specification of ISM
 Set out the requirements for the establishment, implementation
documentation of Info-Sec management systems (ISMS).
 An improvement of part 1 since part 2 addresses the issue of ISMS.
and
Baseline security controls by BS7799-1
(Solms 1999)
Two elements of security control:
 Risk management
 Security baseline manual (identify minimum security control requirements in
organizations)
Two objectives of the CoP:
 Provide a common basis for develop, implement and measure effective security
management practice
 Provide confidence in inter-company trading
Controls listed in CoP define an industry baseline of good security practice, whilst
not all controls will be applicable to every IT environment.  A sub-set of these 10
sections controls are judged to be especially important and are referred to as the key
controls, which would be applicable for ALL organizations, and considered as
mandatory. Key controls always plays a good start point for introducing info-Sec.
10 Key controls of CoP:
 Information Security Policy Document
 Allocation of security responsibilities
 Information security education and training
 Reporting of security incidents
 Virus control
 Business continuity planning
 Control of proprietary records
 Safeguarding of company records
 Compliance with data protection legislation
 Compliance with security policy
Critical factors for the successful implementation of information security in
organizations:
 Security objectives and activities must be based on business objectives and
requirements, and led by business management.
 There must be visible support and commitment from top management
 There must be a good understanding of security risks (threats and
476 REVISION SUMMARY BY Alex Peng
vulnerabilities) to company assets, and the level of security inside the
organization.
 Security must be effectively marketed to all managers and employees
 Comprehensive guidance on security policy standards must be distributed to all
employees and contractors.
3. Combing the process and product evaluation
(Eloff and Solms 2000)
Categories of evaluated IT products and/or systems (TCSEC only check products
whilst ITSEC check both products and systems)
 Database
 System of Communication
 Miscellaneous (其他功能)
 Networks
 Operating Systems (OS)
 PC access
(see example to enhance better understanding from this paper)
BS7799 10 sections: (政策, 组织, 资产, 职员, 物理环境, 计算机和网络, access
control, 系统维护, business continuity planning, compliance 总合格率)
把 product evaluation 放入 section 6, 即 computer and networks management 当中,
就把产品检验和过程检验统一起来了/
Critique(personally): This is only a qualitative analysis without any quantitative
mathematical approach to indicate precisely that how much percentage should be
added into section 6 of BS7799 while combing product evaluation by TCSEC or
ITSEC. Thus this paper can only provides a research direction for future study in this
domain.
------------------------------------------------------------------------------------------------------NOTE: PAPER 8 is such amazing paper which depressed me so much when I was
trying to find what it means…This is some key points I found in this paper:
 Table 2: The development process of BS7799
 Figure 2: The risk management model
 Figure 3: Risk analysis and risk assessment flow chart and explanation
 P453: “four threats”
 P454: “Risk categories”
 Table 7: Maturity of IRM
 Figure 9: Selection methods for ISMS protection
476 REVISION SUMMARY BY Alex Peng
 *Combining figure2, figure5 and table 10 to catch the main contribution of this
paper*