Blowfish Cipher, a symmetric block cipher, handles keys of varying lengths by using them to initialize the P-array and S-boxes. The key is divided into 32-bit blocks which are then XORed with the P-array entries in order. If the key length is less than the total size of the P-array, it wraps around until all entries have been XORed. This preprocessed state of P-array and S-boxes forms the working key for encryption or decryption. For each data block, the algorithm goes through 16 rounds of complex transformations using this working key. Thus, Blowfish can handle keys from 32 bits up to 448 bits, providing flexibility and high security.
