Introduction

Do you ever need to:

• Send absolutely private E-mail to a colleague?
• Receive confidential material from a client?
• Keep sensitive information hidden in a non-secure computer environment?
• Just feel safe knowing your data is for your knowledge only?

These are a few questions that can be answered by Cryptography.

As the Internet and other forms of electronic communication become more prevalent, electronic security is becoming increasingly important. Cryptography is used to protect e-mail messages, credit card information, and corporate data.

Table of Contents:

1. What is Cryptgraphy?

2. There are two main types of encryption

3. Different types of Cryptosystems/Encryptions

4. Public Key Cryptography - Secure or House of Cards?

5. Political and Ethical Issues

6. New Standard on the Way

7. Other Links

What is Cryptography?

The art of protecting information by transforming it (encrypting it) into an unreadable format, called cyphertext. Only those who possess a secret key can decipher (or decrypt) the message into plaintext. Encrypted messages can sometimes be broken by cryptanalysis, also called codebreaking, although modern cryptography techniques are virtually unbreakable.

Cryptography is the enciphering and deciphering of messages.  While cryptosystem is the method of encrypting and decrypting data.  In general terms, the algorithm or theory used to encrypt/decrypt data.

Encryption is the process of changing data into a form that can be read only by the intended receiver. While decryption is the process of decoding data that has been encrypted intoa secret format.  To decipher the message, the receiver of the encrypted data must have the proper decryption key. In traditional encryption schemes, the sender and the receiver use the same key to encrypt and decrypt data.

Encryption is the most effective way to achieve data security.  To read an encrypted file, you must have access to a secret key or password that enables you to decrypt it.  Unencrypted data is called plain text

There are two main types of encryption:

• Asymmetric encryption, also known as, public -key encryption

• Symmetric encryption

An asymmetric encryption is an encryption system in which the sender and receiver of a message share a single, common key that is used to encrypt and decrypt the message.   Symmetric-key systems are simpler and faster, but their main drawback is that the two parties must somehow exchange the key in a secure way.   One example of an asymmetric encryption system is the Data Encryption Standard, DES.

Public-key encryption is a cryptographic system that uses two keys opposed to an asymmetric encryption that only uses one common key.  The two keys used are -- the public key which is known to everyone and the private or secret key known only to the recipient of the message.  An important element to the public key system is that the public and private keys are related in such a way that only the public key can be used to encrypt messages and only the corresponding private key can be used to decrypt them. Moreover, it is virtually impossible to deduce the private key if you know the public key.  One example of a public-key encryption system would be Pretty Good Privacy, PGP.

Different types of Cryptosystems/Encryptions:

• Rivest, Shamir, Adleman, RSA

• Pretty Good Privacy, PGP

• Keyless Encryption, KE

• One-Time Pads, OTP

Public Key Cryptography - Secure or House of Cards?

The basis for the security associated with most public key cryptosystems is the difficulty of factoring large integers. This difficulty is not a proven mathematical assumption, however. Because there is a mathematical relation between the two keys, one could theoretically calculate the private key from the public key. The difficulty and thus the time associated with solving these problems grows exponentially with the size of the key. For example, a computer capable of performing 10^10 computations per second would factor a 100 digit number in 10^40 seconds. Considering that 10^17 is the estimated age of the universe, this is a pretty long time to wait. The likelihood of someone creating an algorithm that would make this anything less than an extremely difficult problem is very low. It would seem reasonable then to come to the conclusion that these public key cryptosystems will remain secure. This may not be the case, however, if one considers non-mainstream forms of computing, particularly quantum computing.

Quantum computing can be viewed as massive parralel computing, but instead of having many processors working simultaniosly, one quantum processor does the work. The theoretical power of this type of computing would decrease the time to solve one of these problems to a fraction of a second for any length of key. This would shatter the security public key algorithms. The question is whether it will ever be practical to build a machine to accomplish this, or will it remain theory. Those in the quantum research community claim that it can be done, but there are many that view quantum computing as an insurmountable problem in itself.