Date Added: Sep 2011
In this paper, the authors have discussed Public Key Encryption, its use in information Encryption, Digital Signature and Key Agreement. This paper discusses some public key algorithms such as RSA, DH, ECDH, DSA, ECDSA, ECC and their explanation. Here the authors have discussed mathematical arithmetic for these algorithms. In private key (symmetric key) cryptography, data exchanged can be protected by encryption. In this data is encrypted by encryption algorithms using Keys. Only users having same key can encrypt/ decrypt the data. For secured communication between two parties they required to exchange secret key between them. Success of this scheme lies in secrecy of the shared key. Length of the key depends on algorithm used.