Lenstra’s method is an effective subexponential algorithm with applications in this field and involves computing points on an elliptic curve over a finite field. (10[1])Diffie and Hellman name a protocol in this field that is used to perform “exchanges” over a channel. This field relies on “hardness” assumptions such as the discrete logarithm problem. So-called “primitives” like the hash SHA-1 are used as the basis for systems in this field. A public key and a private key are used in an algorithm in this field that relies on the difficulty of factoring large numbers, the RSA algorithm. For 10 points, name this branch of computer science that develops secure communication methods. ■END■