Field agents have intercepted the following ciphertext message. Informants state that the ciphersystem is Vigenre. Below is the ciphertext with four repeated sequences underlined. Ciphertext: SDPCB WSRPB UBCPB QUWXB YUWPH ZFRPB TVIPQ SOCTF UBCIQ SOPRO FDPCV W 1. a) For each repetition, give the distance and factors: 1. b) When you begin your cryptanalysis, what are the first two key lengths you will try