# US 7,466,824 B2 · Method and system for encryption of streamed data > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,466,824 B2 - Document ID: US7466824B2 - Status: Granted - Kind: B2 - Application number: 10/681,158 - Filed: 2003-10-09 - Published: 2005-10-20 - Granted: 2008-12-16 - Earliest claimed: 2003-10-09 - Assignees: Nortel Networks Limited - Inventors: Lawrence Gerard Dobranski; Michael Lee - Web page: https://patentgrep.com/patent/US7466824B2 ## CPC - H04K 1/02: by adding a second signal to make the desired signal unintelligible - H04L 9/065: {Encryption by serially and continuously modifying data stream elements, e.g. stream cipher systems, RC4, SEAL or A5/3} - H04L 9/12: Transmitting and receiving encryption devices synchronised or initially set up in a particular manner - H04L 2209/34: Encoding or coding, e.g. Huffman coding or error correction - H04K: SECRET COMMUNICATION; JAMMING OF COMMUNICATION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Method and system for encrypting streamed data employing fast set-up single use keys and self-synchronization. A transmitting handset produces a bitstream of voice data containing the session key and encrypted by an encryption signal based upon the session key. A receiving handset decrypts the incoming bitstream using the encryption signal and recognizes the session key, thereby establishing synchronization. The session key is derived from a seed by applying a first function to the seed. Following the call, the session key is converted into a new seed by application of a second function and the new seed is stored for use in the next call. ## Claims ### Claim 1 A method of synchronizing encryption in a communications network between a transmitting set and a receiving set, the method comprising: (a) creating, at the transmitting set, a bitstream, said bitstream including voice data preceded by a synchronization vector that has been derived from a session key; (b) generating, at the transmitting set, an encryption signal based upon said session key and encrypting said bitstream with said encryption signal; (c) transmitting said encrypted bitstream from the transmitting set to the receiving set; and (d) generating, at the receiving set, said encryption signal based upon said session key and decrypting said encrypted bitstream using said encryption signal to identify said synchronization vector; and (e) synchronizing said encryption signal to said encrypted bitstream based on identification of said synchronization vector to permit recovery of said voice data from said encrypted bitstream. ### Claim 2 (depends on 1) The method claimed in claim 1, wherein said synchronization vector comprises said session key. ### Claim 3 (depends on 2) The method claimed in claim 2, wherein said decrypting includes applying a feedback cipher to said encrypted bitstream to obtain a decrypted output, and comparing said decrypted output with said session key. ### Claim 4 (depends on 1) The method claimed in claim 1, wherein said bitstream includes random bits followed by said synchronization vector, followed by said voice data. ### Claim 5 (depends on 1) The method claimed in claim 1, including calculating said session key from a common seed value. ### Claim 6 (depends on 5) The method claimed in claim 5, wherein said calculating said session key includes applying a first function to said common seed value to generate said session key. ### Claim 7 (depends on 6) The method claimed in claim 6, further including applying a second function to said session key to produce a new seed value for use in subsequent communications. ### Claim 8 A system for the secure transmission of information over a communications network, the system comprising: (a) a transmitting set, said transmitting set having an encryption module, wherein said encryption module receives a session key, generates an encryption signal based upon said session key, generates a bitstream, said bitstream including voice data preceded by a synchronization vector that has been derived from said session key, and encrypts said bitstream with said encryption signal to transmit an encrypted bitstream; and (b) a receiving set, said receiving set including a decryption module, wherein said decryption module receives said encrypted bitstream from said transmitting set, generates said encryption signal based upon said session key, and decrypts said encrypted bitstream using said encryption signal to identify said synchronization vector, wherein said decryption module is configured to synchronize said encryption signal to said encrypted bitstream based on identification of said synchronization vector to permit recovery of said voice data from said encrypted bitstream. ### Claim 9 (depends on 8) The system claimed in claim 8, wherein said synchronization vector comprises said session key. ### Claim 10 (depends on 9) The system claimed in claim 9, wherein said decryption module includes a feedback cipher and a comparator, wherein said feedback cipher produces a decrypted output, and wherein said comparator compares said decrypted output with said session key so as to identify said synchronization vector. ### Claim 11 (depends on 8) The system claimed in claim 8, wherein said bitstream includes random bits followed by said synchronization vector, followed by said voice data. ### Claim 12 (depends on 8) The system claimed in claim 8, wherein said transmitting set includes a common seed value and a cryptographic engine for calculating said session key from said common seed value. ### Claim 13 (depends on 12) The system claimed in claim 12, wherein said cryptographic engine includes a first function for converting said seed value into said session key. ### Claim 14 (depends on 12) The system claimed in claim 12, wherein said cryptographic engine includes a second function for converting said session key into a new common seed value. ### Claim 15 A handset for use in a communications network for secure communications between the handset and a corresponding set, the handset comprising: an encryption module, said encryption module receiving a session key, generating an encryption signal based upon said session key, generating an output bitstream, said output bitstream including voice data preceded by a synchronization vector that has been derived from said session key, and encrypting said output bitstream with said encryption signal to transmit an encrypted bitstream; and a decryption module, said decryption module receiving said session key, generating said encryption signal based upon said session key, receiving an incoming bitstream from the corresponding set, and decrypting said incoming bitstream using said encryption signal to identify said synchronization vector, wherein said decryption module is configured to synchronize said encryption signal to said encrypted bitstream based on identification of said synchronization vector to permit recovery of said voice data from said encrypted bitstream. ### Claim 16 (depends on 15) The handset claimed in claim 15, wherein said synchronization vector comprises said session key. ### Claim 17 (depends on 16) The handset claimed in claim 16, wherein said decryption module includes a feedback cipher and a comparator, wherein said feedback cipher produces a decrypted output, and wherein said comparator compares said decrypted output with said session key so as to identify said synchronization vector. ### Claim 18 (depends on 15) The handset claimed in claim 15, wherein said output bitstream includes random bits followed by said synchronization vector, followed by said voice data. ### Claim 19 (depends on 15) The handset claimed in claim 15, further including a common seed value and a cryptographic engine for calculating said session key from said common seed value. ### Claim 20 (depends on 19) The handset claimed in claim 19, wherein said cryptographic engine includes a first function for converting said seed value into said session key. ### Claim 21 (depends on 19) The handset claimed in claim 19, wherein said cryptographic engine includes a second function for converting said session key into a new common seed value. ### Claim 22 A method for secure transmission of streamed voice data in a network between a transmitting set and a receiving set, the method comprising: (a) providing the transmitting set and the receiving set with a seed value and a predetermined first function; (b) at each of the transmitting set and the receiving set, applying the predetermined first function to the seed value to produce a session key; (c) at the transmitting set, generating an encryption signal based upon said session key generating a bitstream, wherein said bitstream includes a synchronization vector and the streamed voice data, said synchronization vector comprising said session key, and encrypting said bitstream with said encryption signal to produce an encrypted bitstream; (d) transmitting said encrypted bitstream from the transmitting set to the receiving set; and (e) at the receiving set, generating said encryption signal based upon said session key and decoding said encrypted bitstream using said encryption signal to obtain the streamed voice data. ### Claim 23 (depends on 22) The method claimed in claim 22, wherein said providing includes distributing said seed value to the transmitting set and the receiving set by a call server via the network. ### Claim 24 (depends on 22) The method claimed in claim 22, further including receiving an index from a call server, and wherein said step of applying the predetermined first function includes repeating application based upon said index. ### Claim 25 (depends on 22) The method claimed in claim 22, further including applying a second function to said session key to produce a new seed value. ### Claim 26 (depends on 22) The method claimed in claim 22, wherein said decoding said encrypted bitstream includes decrypting said encrypted bitstream to produce a decrypted bitstream and comparing said decrypted bitstream with said session key to identify said synchronization vector. ### Claim 27 A system for secure transmission of streamed voice data in a network, the system comprising: (a) a transmitting set, the transmitting set including an encoder, said encoder having a first cryptographic engine, a vocoder and an encrypter, said first cryptographic engine including a first function and generating a session key from applying said first function to a seed value, said first cryptographic engine further generating an encryption signal based upon said session key, said vocoder generating a bitstream, said bitstream including a synchronization vector and the streamed voice data, said encrypter receiving said bitstream and the encryption signal and producing an encrypted bitstream; and (b) a receiving set, the receiving set including a decoder, said decoder having a second cryptographic engine and a decrypter, said second cryptographic engine including said first function and generating said session key from applying said first function to said seed value, said cryptographic engine further generating said encryption signal based upon said session key, said decrypter receiving said encrypted bitstream and said encryption signal and producing the streamed voice data. ### Claim 28 (depends on 27) The system claimed in claim 27, further including a call server for distributing said seed value to the transmitting set and the receiving set via the network. ### Claim 29 (depends on 27) The system claimed in claim 27, wherein said first and second cryptographic engines each include a second function for converting said session key to a new seed value. ### Claim 30 (depends on 27) The system claimed in claim 27, wherein said synchronization vector comprises said session key. ### Claim 31 (depends on 30) The system claimed in claim 30, wherein said decoder includes a comparator, said comparator receiving said decrypted bitstream and said session key and outputting a sync signal in response to a match between said decrypted bitstream and said session key. ### Claim 32 (depends on 27) The system claimed in claim 27, wherein said encrypter includes an XOR operator. ### Claim 33 (depends on 32) The system claimed in claim 32, wherein said decrypter includes an XOR operator.