Encryption Notes
From CSEP590TU
Revision as of 05:21, 8 November 2004 by John.naegle (talk | contribs)
Contents
Overview
- An encryption scheme is sometimes refered to a cipher
- "Having transformations which are very similar but characterized by keys means that if some particular encryption/decryption tranformation is revealed, then one does not have to redsign the entire scheme but simply charge the key" [1] (page 12)
Quotes
- "The level of information security sought in any particular situation should be commensurate with the value of the information and the loss, financial or otherwise, that might occur" [2]
- "Cryptography, over the ages, has been an art practised by many who have devised ad hoc techniques to meet some of the information secuirty requirements" [3] (page 6)
- "The objectives of information security cannot solely be achived through mathematical algorithms and protocols alone, but required procedural techniques and abidance of laws to achive the desired result" [4] (page 2)
Uses of Encryption
Information Security
- Encryption is one means to achive information security
Objectives
Information has many objectives.
- Privacy
- Data Integrity
- Entity Authentication (Identification)
- Message Authentication
- Signature
- Authorization
- Validation
- Access Control
- Certification
- Timestamping
- Witnessing
- Receipt
- Confirmation
- Ownership
- Anonymity
- Non-repudiation
- Revocation [5] (page 3)
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- Cryptography isn't the only means of providing information security, but rather one set of techniques [6] (page 4)
- The digital age has changed information security dramatically. In the paper age, making thousands of indistinguishable copies copies of was much more difficult. In a digitial society, a means to ensure information security that is independent of the physical medium is required - security must rely on the digital information itself.[7] (page 3). Alteration and creation of digitial data is also easy.
Mathematics
- Intractable problems provide the fundamentals Cryptography systems
- Bijections are used as the tool for encrypting messages and the inverse transformations are used to decrypt [8] (page 8)
- A one-way function from X to Y is "easy" to compute for all x in X, but "hard" to find any x in X such that f(x) = y for essential all elements y in the range of f for X. [9] (page 8)
- I didn't do a very good job transcribing that. (JSN)
- I tend to think of rolling a large rock down a steep hill. (JSN)
- A trapdoor one-way function is a one-way function, that, given some extra information it becomes feasible to find for any given y an x such that f(x) = y.
- Integer factorization
- None one has yet definitvely proved the existence of such functions
- The basis for public-key crptography
Types of Encryption
Public Key Cryptography
Symmetric-key Encryption
Attacks
- An adversary