A method for securely communicating print data from a client computer to a networked printer, the method comprising: providing a first set of computer program instructions from the client computer to the printer; the method being characterized in that: the printer comprises a variable seed source that is coupled to a system bus, the variable seed source sampling a clock signal within the printer to provide a seed (S R) for a pseudo random number generator; the first set of computer program instructions is adapted to cause the printer to generate a pseudo random number using seed (S R) from the variable seed source; and the first set of computer program instructions is further adapted to cause the printer to generate a first encryption key (E P) and a first decryption key (D P) using the pseudo random number; and by the sequential steps of: sending the first encryption key (E P) from the printer to the client computer; encrypting the print data at the client computer using the first encryption key (E P); providing a second set of computer program instructions from the client computer to the printer, the second set of computer program instructions adapted to enable the printer to decrypt print data; sending the encrypted print data from the client computer to the printer; and decrypting the encrypted print data at the printer using the first decryption key (D P) and running the second set of computer program instructions. providing a first set of computer program instructions from the client computer to the printer; the method being characterized in that: the printer comprises a variable seed source that is coupled to a system bus, the variable seed source sampling a clock signal within the printer to provide a seed (S R) for a pseudo random number generator; the first set of computer program instructions is adapted to cause the printer to generate a pseudo random number using seed (S R) from the variable seed source; and the first set of computer program instructions is further adapted to cause the printer to generate a first encryption key (E P) and a first decryption key (D P) using the pseudo random number; the printer comprises a variable seed source that is coupled to a system bus, the variable seed source sampling a clock signal within the printer to provide a seed (S R) for a pseudo random number generator; the first set of computer program instructions is adapted to cause the printer to generate a pseudo random number using seed (S R) from the variable seed source; and the first set of computer program instructions is further adapted to cause the printer to generate a first encryption key (E P) and a first decryption key (D P) using the pseudo random number; and by the sequential steps of: sending the first encryption key (E P) from the printer to the client computer; encrypting the print data at the client computer using the first encryption key (E P); providing a second set of computer program instructions from the client computer to the printer, the second set of computer program instructions adapted to enable the printer to decrypt print data; sending the encrypted print data from the client computer to the printer; and decrypting the encrypted print data at the printer using the first decryption key (D P) and running the second set of computer program instructions. sending the first encryption key (E P) from the printer to the client computer; encrypting the print data at the client computer using the first encryption key (E P); providing a second set of computer program instructions from the client computer to the printer, the second set of computer program instructions adapted to enable the printer to decrypt print data; sending the encrypted print data from the client computer to the printer; and decrypting the encrypted print data at the printer using the first decryption key (D P) and running the second set of computer program instructions.