1. A method for establishing a secure communications session between a first computing device and a second computing device, the method comprising:
retrieving a first random number at the first computing device;
retrieving a second random number at the second computing device;
retrieving at least one public-private key pair including a public key and a private key;
sending a message from said second computing device to said first computing device, said message from said second computing device to said first computing device including said first random number and the public key of said at least one public-private key pair to thereby share at least said first random number with said first communication device, said message from said second computing device to said first computing device being encrypted with an encoded password;
providing said encoded password to said first computing device;
using said provided encoded password to decrypt said first message at said first computing device to obtain at least said first random number that said second computing device sent in said message from said second computing device to said first computing device;
sending a message from said first computing device to said second computing device, said message from said first computing device to said second computing device including said second random number, said first computing device encrypting said message it sends to said second computing device;
generating, at each of said first and second computing devices, a shared session key by combining said first random number and second random number that is now available to each of said first and second computing devices through said above-mentioned message exchanges; and
using said shared session key to establish a secure private communication session between said first and second computing devices.
2. The method of claim 1, wherein said combining includes a logical function.
3. The method of claim 2, wherein said logical function includes an exclusive or (XOR) function.
4. The method of claim 1 wherein said password comprises a user password.
5. The method of claim 1 wherein said encoded password comprises a user password encoded with a hash function.
6. The method of claim 1 further including generating said first and second random numbers on demand.
7. The method of claim 1 further including generating said public-private key pair on demand.
8. The method of claim 1 wherein said second computing device comprises a server, and said first computing device comprises a client wishing to communicate with said server.
9. The method of claim 1 wherein said first computing device uses said public key obtained from said message send from said second computing device to said first computing device to encrypt said message from said first computing device to said second computing device.
10. The method of claim 1 further including prompting a user to input a password into said first computing device, and encoding said inputted password at said first computing device to provide said encoded password.
11. A method for establishing secure communication between a calling party and a called party, comprising:
generating, on demand at the called party, an asymmetric key pair including a public key and a private key;
transmitting, from said called party to said calling party, a first encrypted message including a first random number and said public key of said asymmetric key pair, said called party encrypting said first message with an encoded password known to both the calling party and the called party;
said calling party receiving and decrypting said first encrypted message using said encoded password to obtain said first random number and said public key;
said calling party transmitting, to said called party, a second encrypted message including a second random number, said calling party encrypting said second message with said public key of said asymmetric key pair;
said called party receiving and decrypting said second encrypted message to obtain said second random number;
said calling and called parties each independently applying said now-shared first and second random numbers to combining functions to thereby each independently generate a shared secret key; and
said calling and called parties encrypting further communications therebetween at least in part using said shared secret key.
12. The method of claim 11 wherein said symmetric encryption key comprises a password.
13. The method of claim 11 wherein said called party comprises a server and said calling party comprises a client that wishes to communicate with said server.
14. The method of claim 11 further including said called party retrieving said password or encoded password from a user database in response to receipt of a request by said calling party for a secure communication.
15. The method of claim 11 wherein said generating comprises generating said asymmetric key pair at said called party.
16. The method of claim 11 wherein said encrypted communication proceeds between said calling party and said called party without requiring said calling party to generate an asymmetric key pair.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1) A fuel injector (1) for an internal combustion engine; the injector terminating with a nozzle for injecting fuel into a relative cylinder of the engine, and comprising:
a hollow injector body (2) extending in an axial direction (3);
a control rod (10) movable axially with respect to said injector body (2) to openclose said nozzle;
a control servovalve housed in said injector body (2) and comprising:
a) an electro-actuator;
b) a control chamber (23), which is bounded axially at one side by said control rod (10), communicates with a fuel inlet (4), and has a discharge passage (26, 48) comprising a calibrated portion (42, 52); and
c) a shutter (17) movable axially, under the control of said electro-actuator, between a closed position, in which it closes said discharge passage (26, 48), and an open position, in which it opens said discharge passage (26, 48) to vary the pressure in said control chamber (23) and so produce axial movement of said control rod (10);
characterized in that:
said control servovalve also comprises an axial rod (33) fixed with respect to said injector body (2) and comprising an outer lateral surface (34) through which said discharge passage (26, 48) comes out;
said shutter (17) is fitted to said outer lateral surface (34) to slide axially in substantially fluidtight manner, and, in said closed position, closes said discharge passage (26, 48) so as to be subjected to substantially zero resultant axial pressure by the fuel; and
said calibrated portion (42, 52) is so formed as to produce swirl andor cavitation in the fuel outflow near to the closing area between said shutter (17) and said axial rod (33).
2) An injector as claimed in claim 1, characterized in that said calibrated portion (42, 52) is formed close to the outlet of said discharge passage (26, 48).
3) An injector as claimed in claim 1, characterized in that said calibrated portion (42) is formed in said axial rod (33).
4) An injector as claimed in claim 3, characterized in that said calibrated portion (42) extends radially.
5) An injector as claimed in claim 1, characterized in that said discharge passage (48) is formed in a straight direction (49).
6) An injector as claimed in claim 1, characterized in that said discharge passage (26, 48) terminates with a portion (43, 53) having a cross section larger than that of said calibrated portion (42, 52).
7) An injector as claimed in claim 1, characterized in that said discharge passage (26, 48) is formed entirely in a single fixed body (28) comprising said axial rod (33) and axially defining said control chamber (23) at the opposite side to said control rod (10).
8) An injector as claimed in claim 7, characterized in that said control chamber (23) is bounded radially by a tubular portion (11a) forming part of a valve body (8) distinct from said fixed body (28); said fixed body (28) comprising a base portion (30) larger in diameter than said axial rod (33), axially defining said control chamber (23), and gripped axially against said valve body (8).
9) An injector as claimed in claim 1, characterized in that said control chamber (23) is bounded radially by a tubular portion (11a) in turn defining outwards an annular chamber (25c) connecting said control chamber (23) to said inlet (4); said annular chamber (25c) comprising a first annular gap (61) housing a sealing ring (62) interposed between said tubular portion (11a) and said injector body (2), and a second annular gap (59) bounded axially by a shoulder (60) of said tubular portion (11a) and smaller radially than said first annular gap (61).
10) An injector as claimed in claim 9, characterized in that said first and said second annular gap (61, 59) are defined, on said injector body (2), by respective cylindrical surfaces (57, 56) connected to each other by a conical surface (58) converging from the first to the second annular gap.