Information security

Information SecuritySINA BAGHERINEZHAD

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University of TehranFaculty of Management

Some Statistics

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Agenda

History

Definitions

Basic principles

Controls

Access Control

Cryptography

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History

ATBASH (600 BC)

Scytale (486 BC)

Caesar cipher (50 BC)

Alberti cipher (1466)

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Definitions of Information Security

Preservation of confidentiality, integrity and availability of information.

(ISO/IEC 27000:2009)

The protection of information and information systems from unauthorized

access, use, disclosure, disruption, modification, or destruction in order to

provide confidentiality, integrity, and availability. (CNSS, 2010)

Ensures that only authorized users (confidentiality) have access to

accurate and complete information (integrity) when required

(availability). (ISACA, 2008)

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Basic Principles

Confidentiality

Integrity

Availability

Authenticity

Non-repudiation

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Controls

Administrative

Logical

Physical

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Access Control

Identification

Authentication

Something you know: things such as a PIN, a password, or your mother's maiden

name.

Something you have: a driver's license or a magnetic swipe card.

Something you are: biometrics, including palm prints, fingerprints, voice prints

and retina (eye) scans.

Authorization (run, view, create, delete, or change)

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Cryptography

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Symmetric-key Cryptography

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Man-in-the-middle attack (MITM)

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Diffie-Hellman key exchange

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Public-key (Asymmetric) Cryptography

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RSA (cryptosystem)

Key generation:

1. Choose two distinct prime numbers p and q.

2. Compute n = pq.

3. Compute φ(n) = φ(p)φ(q) = (p − 1)(q − 1)

4. Choose an integer e such that 1 < e < φ(n) and gcd(e, φ(n)) = 1

5. Determine d as d.e ≡ 1 (mod φ(n))

Public key: (n, e)

Private key: (n, d)

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RSA (cryptosystem)

Encryption

1. Bob wishes to send message M to Alice.

2. He first turns M into an integer m, such that 0 ≤m < n

3. He then computes the ciphertext c corresponding to 𝐶 ≡ 𝑚𝑒 (mod n)

4. Bob then transmits c to Alice.

Decryption

1. Alice can recover m from c via computing 𝑚 ≡ 𝑐𝑑 (mod n)

2. Given m, she can recover the original message M.

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Digital signature

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References:

www.wikiperdia.com

www.scmagazine.com

www.comodo.com

www.billatnapier.com

www.noweco.com

www.ibm.com

www.iso.org

www.27000.org

نشر نص/ دکتر علی ذاکرالحسینی، دکتر احسان ملکیان /امنیت داده ها

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