Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

Standards and ProtocolsStandards and Protocols

Chapter 7

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

Objectives• Identify the standards involved in establishing

an interoperable Internet PKI.

• Explain interoperability issues with PKI standards.

• Describe how the common Internet protocols implement the PKI standards.

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

Key TermsKey Terms

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

Key Terms Key Terms ((continuedcontinued))

• Transport Layer Security (TLS)• Wired Equivalent Privacy (WEP) - compromised

• Wireless Application Protocol (WAP)

• Wireless Transport Layer Security (WTLS)

• X.509

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

Standards and ProtocolsStandards and Protocols• Commercial use of the Internet has been one of the

biggest growth industries since the 1990s.

• Public key infrastructures (PKI) are implemented to secure transactions online.

• Three categories of standards associated with PKI:– Standards that define the PKI

– Standards that define the interface between applications and the underlying PKI

– Other standards

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

Relationships Between PKI Standards and Protocols

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

PKIX Standard and PKCSPKIX Standard and PKCS

• Two main standards for implementing PKI.

• Both based on X.509 standard.

• PKIX produced by Internet Engineering Task Force (IETF); interactions and operations have four component types:– The user, certificate authority (CA), registration authority

(RA), and the certificate revocation list (CRLs)

• PKCS produced by RSA security.

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

The PKIX ModelThe PKIX Model

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

Public Key Cryptography Standards (PKCS)

• Public Key Cryptography Standards (PKCS) fills gaps in standards that existed for implementing PKI.

• PKCS is composed of 13 active standards and 2 discontinued standards.

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

15 Public Key Cryptography Standards Standard Title and Description

PKCS #1 RSA Cryptography Standard: Definition of the RSA encryption standard

PKCS #2 Incorporated into PKCS #1, no longer active

PKCS #3 Diffie-Hellman Key Agreement Standard: Definition of the Diffie-Hellman key-agreement protocol

PKCS #4 Incorporated into PKCS #1, no longer active

PKCS #5 Password-Based Cryptography Standard: Definition of a password-based encryption (PBE) method for generating a secret key

PKCS #6 Extended-Certificate Syntax Standard: Definition of an extended certificate syntax that was made obsolete by X.509 v3

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

X.509• X.509 is the portion of the X.500 standard that

addresses the structure of certificates used for authentication.

• X.509 specifies standard formats for public key certificates, certificate revocation lists, and Attribute Certificates.

• Version 3 is the current version of the X.509 standard.

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

X.509 Certificate ComponentsField Name Field Description

Certificate Signature

X.509 version used for this certificate: Version 1 = 0, Version 2 = 1, Version 3 = 2

Serial Number A nonnegative integer assigned by the certificate issuer that must be unique to the certificate.

Signature Algorithm Algorithm Parameters (optional)

The algorithm identifier for the algorithm used by the CA to sign the certificate. The optional Parameters field is used to provide the cryptographic algorithm parameters used in generating the signature.

Issuer Identification for the entity that signed and issued the certificate. This must be a distinguished name within the hierarchy of CAs.

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

X.509 Certificate Components (continued)

Validity Not valid before time Not valid after time

Validity specifies a period of time during which the certificate is valid, using a “not valid before” time and a “not valid after” time (expressed in UTC or in a generalized time).

Subject The name for the certificate owner.

Subject Public Key Info This field consists of an encryption algorithm identifier followed by a bit string for the public key.

Issuer Unique ID Optional for versions 2 and 3—a unique bit-string identifier for the CA that issued the certificate.

Subject Unique ID Optional for versions 2 and 3—a unique bit-string identifier for the subject of the certificate.

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

X.509 Certificate Components (continued)

 Extension ID Critical Extension  Value

Optional for version 3—the extension area consists of a sequence of extension fields containing an extension identifier, a Boolean field indicating whether the extension is critical, and an octet string representing the value of the extension. Extensions can be defined in standards or defined and registered by organizations or communities.

Thumbprint AlgorithmParameters (optional)

This field identifies the algorithm used by the CA to sign this certificate. This field must match the algorithm identified in the Signature Algorithm field.

Thumbprint The signature is the bit-string hash value obtained when the CA signed the certificate. The signature certifies the contents of the certificate, binding the public key to the subject.

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

Secure Sockets Layer (SSL) and Transport Layer Security (TLS)

• Provide secure connections between the client and server for exchanging information

• Provide authentication and confidentiality of information transfers

• Provide data integrity and security over networksby encrypting network connections at the transport layer

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

SSL/TLS• TLS & SSL are not interchangeable; TLS is the more

modern of the two.

• TLS is superior to SSL since SSL’s use of hashing forces a reliance on MD5 rather than SHA1.

• http://tools.ietf.org/html/rfc5246#page-4

• Web Server Software – market share

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

TLS Record Protocol• TLS Record protocol send data by:

– Fragmenting message data into manageable blocks

– Optionally compressing the data

– Applying a message authentication code (MAC) to the data

– Encrypting the data

– Transmitting the results

• Received data is decrypted, verified, decompressed, and reassembled and sent on to the higher-level client.

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

TLS Handshake Protocol

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

Pretty Good Privacy (PGP)

• Program used to encrypt and decrypt e-mails and files

• Provides the ability to digitally sign a message• How PGP works

– Creator uses encryption program to create a key pair.• Public key designed to give freely to others• Private key designed to be known only be the creator

– Messages encrypted by the sender using the recipients public key.

– The recipients private key is used to decrypt the message.

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

How PGP Works

• PGP uses a variation of the standard public key encryption process. – An individual (here called the creator) uses the encryption

program to create a pair of keys. – One key is known as the public key and is designed to be given

freely to others.– The other key is called the private key and is designed to be

known only by the creator.– Individuals who want to send a private message to the creator

encrypt the message using the creator’s public key. – The algorithm is designed such that only the private key can

decrypt the message, so only the creator will be able to decrypt it.

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

HTTPS

• Uses SSL to secure Hypertext Transfer Protocol (HTTP) communications

• Uses TCP port 443 • Supports 40-bit RC4 encryption algorithm and

128-bit encryption

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

IPsec

• Collection of IP security features designed to introduce security at the network layer

• Optional in IPv4, required in IPv6• Two types of security service:

– Transport mode can be used to ensure authentication and confidentiality for data alone.

– Tunnel mode can be used to ensure authentication and confidentiality for both data and header.

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

Wireless Transport Layer Security (WTLS)

• Provides security for Wireless Application Protocol (WAP)

• Implemented due to the limited memory and processing of WAP-enabled phones

• Implemented in one of three classes:– Class 1: anonymous authentication– Class 2: server authentication– Class 3: server and client authentication

• Class 3 the strongest form of WTLS

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

Wired Equivalent Privacy (WEP)

• Used to protect wireless communications from being intercepted

• Used to prevent unauthorized access to the wireless network

• Part of the original 802.11 standard• WEP 1 supported 64 bit encryption; WEP 2

supports 128 bit encryption• Both WEP 1 and WEP 2 vulnerable to various

attack vectors

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

WEP Security Issues• Wireless networking with 802.11 is common.

• WEP is an optional security protocol with significant issues:– It uses a 24-bit initialization vector as a seed.

– This allows for more than 16 million vectors.

– At modern networks speeds it does not take long for initialization vectors to repeat.

– The secret key is only 40 bits, and is also quickly breakable.

• Some provides use 128-bit WEP but is almost equally vulnerable.

Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

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Principles of Computer Security:CompTIA Security+® and Beyond, Third Edition

Chapter Summary• Identify the standards involved in establishing

an interoperable Internet PKI.

• Explain interoperability issues with PKI standards.

• Describe how the common Internet protocols implement the PKI standards.