System and method of dynamic key generation for digital communications

A method for symmetric-key encrypted transmission of data between a sender and receiver comprising the following steps, in order:

• (a) exchanging a initialization string by secure, external transmission between sender and receiver;
• (b) generating an encryption key by pseudo-random-function means operating on data comprising the initialization string at both sender and receiver;
• (c) encrypting the next block of data into ciphertext by symmetric-key-encryption algorithm means comprising the encryption key at the sender;
• (d) transmitting the ciphertext to the receiver;
• (e) decrypting the ciphertext by symmetric-key-encryption algorithm means comprising the encryption key at the receiver;
• (f) generating a new encryption key at both sender and receiver by pseudo-random-function means operating on data comprising the initialization string;
• and
• repeating the steps from (d) forward repeatedly until the data is exhausted.

A method for symmetric-key encrypted transmission of block-organized data between a sender and receiver comprising the following steps, in order:

• (a) exchanging a initialization string by secure, external means between sender and receiver;
• (b) generating one or more intermediate keys by pseudo-random-function means operating on data comprising the initialization string at both sender and receiver;
• (c) generating an encryption key by pseudo-random-function means operating on data comprising the intermediate keys at both sender and receiver;
• (d) encrypting the next block of data into ciphertext by symmetric-key-encryption algorithm means comprising the encryption key at the sender;
• (e) transmitting the ciphertext to the receiver;
• (f) decrypting the ciphertext by symmetric-key-encryption algorithm means comprising the encryption key at the receiver;
• (g) generating new intermediate keys at both sender and receiver by pseudo-random-function means operating on data comprising the previous intermediate keys;
• and
• repeating the steps from (c) forward repeatedly until the data is exhausted.

A method for symmetric-key encrypted transmission of data between a sender and receiver comprising the following steps, in order:

• (a) exchanging a initialization string by secure, external transmission between sender and receiver;
• (b) generating a master recovery key by pseudo-random function means from data comprising the initialization string;
• (c) generating a first intermediate key by pseudo-random-function means operating on data comprising the master recovery key at both sender and receiver;
• (d) generating one or more second keys by pseudo-random-function means operating on data comprising the first intermediate key at both sender and receiver;
• (e) generating an encryption key by pseudo-random-function means operating on data comprising the second intermediate keys at both sender and receiver;
• (f) encrypting the next block of data into ciphertext by symmetric-key-encryption algorithm means comprising the encryption key at the sender;
• (g) transmitting the ciphertext to the receiver;
• (h) decrypting the ciphertext by symmetric-key-encryption algorithm means comprising the encryption key at the receiver;
• (i) generating new second intermediate keys at both sender and receiver by pseudo-random-function means operating on data comprising the previous intermediate keys;
• and
• repeating the steps from (d) forward repeatedly until the data is exhausted.

A method for generating and updating encryption keys for use in symmetric-key encrypted transmission between a sender and receiver, in which pre-existing host software includes encryption and decryption algorithms and further includes signaling means, comprising the following steps, in order:

• a) exchanging an initialization string by secure, external means between sender and receiver;
• b) generating one or more intermediate keys by pseudo-random-function means operating on data comprising the initialization string at both sender and receiver;
• c) generating an encryption key by pseudo-random-function means operating on data comprising the intermediate keys at both sender and receiver;
• d) generating new intermediate keys at both sender and receiver by pseudo-random-function means operating on data comprising the previous intermediate keys;
• and
• e) repeating the steps from (b) forward repeatedly when signaled by the host software.