1. A variable capacitor comprising:
electrodes, the variable capacitor being used by changing capacitance by application of direct current voltage Vdc and high-frequency voltage Vrms across the electrodes,
wherein, when an effective voltage value of high-frequency voltage Vrms is with in a range from 1 to 4 V of voltage values of direct current voltage Vdc, there is substantially no fluctuation caused by application of high-frequency voltage Vrms with respect to a change of the capacitance caused by application of direct current voltage Vdc.
2. The variable capacitor of claim 1, wherein when the direct current voltage Vdc is within a range of 1 to 4 V, a ratio (C4.0 dcC1.0 dc) between capacitance C1.0 dc in the case of Vdc=1 V and capacitance C4.0 dc in the case of Vdc=4 V is 0.25 to 0.85, and in a frequency range of 100 MHz to 10 GHz, a ratio (C4.0 rmsC0.1 rms) between capacitance C0.1 rms in the case of a high frequency voltage Vrms=0.1 V and capacitance C4.0 rms in case of the high-frequency voltage Vrms\u22124 V is 0.95 to 1.05.
3. The variable capacitor of claim 1, wherein a plurality of variable capacitor elements using a dielectric material whose dielectric constant changes through voltage application are connected to each other in series, and the direct current voltage is applied to each of the variable capacitor elements connected in series.
4. The variable capacitor of claim 1, wherein a plurality of varactor diodes are connected to each other in series, and the direct current voltage is applied to each of the varactor diodes connected in series.
5. The variable capacitor of claim 3, wherein the dielectric material whose dielectric constant is changed by voltage application is made of perovskite-type oxide crystal grains containing at least Ba, Sr and Ti.
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. An image verification system comprising:
an image input apparatus;
an image verification apparatus;
a storage apparatus;
a user information input apparatus; and
a key generation apparatus,
wherein said user information input apparatus sends user information relating to a user to said key generation apparatus, and sends the user information to said image input apparatus,
wherein said key generation apparatus receives the user information from said user information input apparatus, generates a public key which corresponds to the user information, generates a private key which corresponds to the user information, sends the private key corresponding to the user information to said image input apparatus, and sends the user information and the public key corresponding to the user information to said storage apparatus,
wherein said storage apparatus receives the user information and the public key corresponding to the user information from said key generation apparatus, and sends the public key corresponding to the user information to said image verification apparatus,
wherein said image input apparatus receives the user information from said user information input apparatus, receives the private key corresponding to the user information from said key generation apparatus, generates verification data for image data using the private key corresponding to the user information, and sends the user information, the verification data, and the image data to one of said image verification apparatus and a storage medium, and
wherein said image verification apparatus receives the user information, the verification data, and the image data from one of said image verification apparatus and the storage medium, receives the public key corresponding to the user information from said storage apparatus, and verifies whether the image data has been altered or not using the verification data and the public key corresponding to the user information.
2. An image verification system comprising:
an image input apparatus;
an image verification apparatus;
a storage apparatus;
a user information input apparatus; and
a key generation apparatus,
wherein said user information input apparatus sends user information relating to a user to said key generation apparatus, and sends the user information to said image input apparatus,
wherein said key generation apparatus receives the user information from said user information input apparatus, generates a private key which corresponds to the user information, sends the private key corresponding to the user information to said image input apparatus, and sends the user information and the private key corresponding to the user information to said storage apparatus,
wherein said storage apparatus receives the user information and the private key corresponding to the user information from said key generation apparatus, and sends the private key corresponding to the user information to said image verification apparatus,
wherein said image input apparatus receives the user information from said user information input apparatus, receives the private key corresponding to the user information from said key generation apparatus, generates verification data for image data using the private key corresponding to the user information, and sends the user information, the verification data, and the image data to one of said image verification apparatus and a storage medium, and
wherein said image verification apparatus receives the user information, the verification data, and the image data from one of said image verification apparatus and the storage medium, receives the private key corresponding to the user information from said storage apparatus, and verifies whether the image data has been altered or not using the verification data and the private key corresponding to the user information.
3. The image verification system according to claim 1, wherein said image input apparatus is configured to request said key generation apparatus to send the private key corresponding to the user information.
4. The image verification system according to claim 1, wherein said storage apparatus is configured to store the user information and the public key corresponding to the user information in a storage unit.
5. The image verification system according to claim 1, wherein said image verification apparatus is configured to request said storage apparatus to send the public key corresponding to the user information.
6. The image verification system according to claim 1, wherein said image input apparatus is configured to act as a camera.
7. The image verification system according to claim 1, wherein said image input apparatus is configured to act as a scanner.
8. The image verification system according to claim 2, wherein said image input apparatus is configured to request said key generation apparatus to send the private key corresponding to the user information.
9. The image verification system according to claim 2, wherein said storage apparatus is configured to store the user information and the private key corresponding to the user information in a storage unit.
10. The image verification system according to claim 2, wherein said image verification apparatus is configured to request said storage apparatus to send the private key corresponding to the user information.
11. The image verification system according to claim 2, wherein said image input apparatus is configured to act as a camera.
12. The image verification system according to claim 2, wherein said image input apparatus is configured to act as a scanner.
13. A method comprising:
sending, from a user information input apparatus to a key generation apparatus, user information relating to a user;
sending, from the user information input apparatus to an image input apparatus, the user information;
after the key generation apparatus receives the user information from the user information input apparatus, generating, by the key generation apparatus, a public key which corresponds to the user information;
after the key generation apparatus receives the user information from the user information input apparatus, generating, by the key generation apparatus, a private key which corresponds to the user information;
sending, from the key generation apparatus to the image input apparatus, the private key corresponding to the user information;
sending, from the key generation apparatus to a storage apparatus, the user information and the public key corresponding to the user information;
after the storage apparatus receives the user information and the public key corresponding to the user information from the key generation apparatus, sending, from the storage apparatus to an image verification apparatus, the public key corresponding to the user information;
after the image input apparatus receives the user information from the user information input apparatus and receives the private key corresponding to the user information from the key generation apparatus, generating verification data for image data using the private key corresponding to the user information;
sending, from the image input apparatus to one of the image verification apparatus and a storage medium, the user information, the verification data, and the image data; and
after the image verification apparatus receives the user information, the verification data, and the image data from one of the image input apparatus and the storage medium, and receives the public key corresponding to the user information from the storage apparatus, verifying, by the image verification apparatus, whether the image data has been altered or not using the verification data and the public key corresponding to the user information.
14. The method according to claim 13, further comprising requesting the key generation apparatus to send, to the image input apparatus, the private key corresponding to the user information.
15. The method according to claim 13, further comprising storing the user information and the public key corresponding to the user information in a storage unit included in the storage apparatus.
16. The method according to claim 13, further comprising requesting the storage apparatus to send, to the image verification apparatus, the public key corresponding to the user information.
17. The method according to claim 13, wherein the image input apparatus is configured to act as a camera.
18. The method according to claim 13, wherein the image input apparatus is configured to act as a scanner.
19. A method comprising:
sending, from a user information input apparatus to a key generation apparatus, user information relating to a user;
sending, from the user information input apparatus to an image input apparatus, the user information;
after the key generation apparatus receives the user information from the user information input apparatus, generating, by the key generation apparatus, a private key which corresponds to the user information;
sending, from the key generation apparatus to the image input apparatus, the private key corresponding to the user information;
sending, from the key generation apparatus to a storage apparatus, the user information and the private key corresponding to the user information;
after the storage apparatus receives the user information and the private key corresponding to the user information from the key generation apparatus, sending, from the storage apparatus to an image verification apparatus, the private key corresponding to the user information;
after the image input apparatus receives the user information from the user information input apparatus and receives the private key corresponding to the user information from the key generation apparatus, generating verification data for image data using the private key corresponding to the user information;
sending, from the image input apparatus to one of the image verification apparatus and a storage medium, the user information, the verification data, and the image data; and
after the image verification apparatus receives the user information, the verification data, and the image data from one of the image input apparatus and the storage medium, and receives the private key corresponding to the user information from the storage apparatus, verifying, by the image verification apparatus, whether the image data has been altered or not using the verification data and the private key corresponding to the user information.
20. The method according to claim 19, further comprising requesting the key generation apparatus to send, to the image input apparatus, the private key corresponding to the user information.
21. The method according to claim 19, further comprising storing the user information and the private key corresponding to the user information in a storage unit included in the storage apparatus.
22. The method according to claim 19, further comprising requesting the storage apparatus to send, to the image verification apparatus, the private key corresponding to the user information.
23. The method according to claim 19, wherein the image input apparatus is configured to act as a camera.
24. The method according to claim 19, wherein the image input apparatus is configured to act as a scanner.