4permutations 1. let a "small block cipher be a function f which maps 8-bit plaintexts m e (0,1)8 to 8-bit ciphertexts c e (0,1)8. however, function f must be 1-1 or otherwise it would be impossible to invert a block cipher, i. e. compute (using the block cipher key) the plaintext f(c) given ciphertext c. how many "small" block ciphers are there? students if each student must have a computer and computers cannot be shared? capital letters but with no repeated characters? 2. there are 10 computers and 5 students. in how many ways can computers be assigned to 3. recall problem 1. how many 8-character passwords are there made of either lower-case or . how many 10-digit decimal strings are there in which there is no repeated digits? 5. how many 10-digit decimal strings are there in which there is no repeated digits and where 5" occurs before "6"? (by "before" i mean "anywhere before" and not "mmediately before", e. g. string (5,0, 1, 2, 3, 4, 7, 8, 9, 6) is included.) 6. how many 10-digit decimal strings are there in which there is no repeated digits and where "5" and "6" are next to each other?