Cryptanalysis is the analysis of encrypted information to deduce the original plaintext without access to the encryption key. An example is breaking an encrypted message. A digital stream cipher has components like a keystream generator and combining function that encrypts plaintext bit-by-bit using a pseudorandom keystream. Key management faces challenges of securely generating, storing, distributing, and revoking cryptographic keys. Key splitting involves dividing a key into parts while key wrapping uses a key to encrypt another key for transmission.