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[2])Diffie and Hellman name a protocol in this field that is used to perform “exchanges” (10[1])over a channel. This field relies on “hardness” assumptions such as the discrete logarithm problem. So-called “primitives” like the hash SHA-1 (10[1])are used (10[1])as the basis for systems in this field. A public key and a private key (10[1]-5[2])are used in an (10[1])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 (10[1])methods. ■END■ (10[2])