Evaluation of Authentication Algorithms for Small Devices

A. Appendix - First Part
A.1 RSA Public-Key-Algorithm
The RSA Algorithm is the typical example for a Public-Key Algorithm. It uses a
system of asymmetric keys. Which means, there exists a key-pair. With a public part
and a private part. Messages encrypted whith the public key, can only be decrypted
with the corresponding private key.
A.1.1 Creating the keys
This section describes, how the keys are created:
• Choose two very large primes p and q
• Compute n = p· q
• Compute z = (p − 1)(q − 1)
• Choose a private key d, being coprime to z
• Compute the corresponding public key e, satisfying e· d = 1mod z
Now the key-pair is ready for usage.
A.1.2
Encryption and Decryption
After creating the keys, and distributing the public part, messages can be encrypted
by anyone and decrypted by the holder of the secret key.
• Messages are Strings of Bits