The Continuing Story of Alice and Bob: A Discussion of RSA Cryptography
Neumann, Nicholas D.
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RSA has been, and continues, to be an essential tool of cryptography in a large part because of the mathematics that makes up the algorithm. The main mathematical element, modular exponentiation, with the help of mathematical properties inherent in prime numbers, provides the framework through which RSA works, and allows the algorithm the flexibility to act as both a cryptosystem and a digital signature scheme. In most cases RSA is used in conjunction with other cryptographic tools such as hash functions, secret key cryptosystems, block and/or stream ciphers, and digital signatures in order to increase security. For example, RSA is an essential component of systems such as PGP, where the algorithm acts as the digital signature scheme, providing a way for users to securely identify each other in email and other PGP mediums. With recent advances in palm pilots, especially when they are used in conjunction with wireless communication, RSA is beginning to be used more and more on its own. As with the Internet, anyone can intercept data sent over wireless communication, and so cryptographic schemes are necessary to encipher this data. However, palm pilots do not have the capacity to combine very many cryptographic tools to create quick and easy security, and so they use the RSA algorithm alone as a cryptosystem. In cases such as this the security of the RSA algorithm comes from the key-size, which at this time is usually set at 1024 bits. Since the largest key-size that has been cracked so far is 512-bit and since the 567 -bit key has stood as the next largest key for two and a half years now, the 1 024-bit keys provide the perfect protection for palm pilots and other such small computers. Also, since the 512-bit key was cracked, the 2048-bit keys have reached the point where they do not take an exceptionally large amount of time to create, and so are in use more and more. As long as this trend of larger key sizes becoming easier to create as smaller key sizes are cracked continues, the RSA Algorithm w!ll continue to be an industry standard for encryption.