In this illustration we also see Alice, Bob, and Trudy in the same positions as in the previous figure. A blue arrow labeled "Plaintext" extends from the left side of the figure to Alice's computer, which is now labeled "Encryption algorithm." A key labeled KA is associated with the encryption algorithm. A blue arrow, labeled "Ciphertext," extends from the encryption algorithm to Bob's computer, which is now labeled "Decryption algorithm." A key labeled KB is associated with the decryption algorithm. The blue line extending from the encryption algorithm veers off and also points to Trudy, and a blue arrow extends from Trudy and rejoins the arrow extending from the encryption algorithm. A blue arrow labeled "Plaintext" extends from the decryption algorithm to the right side of the figure.