Data sharing method and device

1. A data sharing method, comprising:

receiving a request by a second user through a uniform resource locator (URL) for a user key of a shared file of a first user, wherein the second user is a legitimate user authorized by the first user through a trust center to access the shared file of the first user and the shared file of the first user is a shared file encrypted using the user key of the first user;

obtaining, according to the URL, a file description of the shared file of the first user from a cloud server, wherein the file description is a file description obtained by encrypting the user key of the first user using a public key of the trust center, wherein obtaining the file description of the shared file of the first user from the cloud server comprises:

obtaining the shared file of the first user corresponding to the URL;

decrypting the obtained shared file of the first user using the user key of the first user to obtain an unencrypted version of the shared file of the first user;

encrypting the unencrypted version of the shared file of the first user using a temporary key to obtain a temporary file;

uploading the temporary file to the cloud server; and

obtaining a temporary URL that is delivered by the cloud server and corresponds to the temporary file;

decrypting the file description by using a private key corresponding to the public key of the trust center to obtain the user key of the first user; and

sending the user key of the first user to the second user, wherein sending the user key of the first user to the second user comprises sending the temporary URL and the temporary key to the second user.

2. A data sharing method comprising:

encrypting a file to be uploaded to a cloud server, encrypting using a user key of a first user to obtain an encrypted shared file of the first user;

encrypting the user key of the first user using a public key of a trust center;

using the encrypted user key of the first user as a file description;

uploading the encrypted shared file of the first user and the file description to the cloud server;

receiving a uniform resource locator (URL) that is sent by the cloud server and corresponds to the shared file of the first user;

authorizing, through the trust center, a second user to access the shared file of the first user; and

sending the URL to the second user,

wherein obtaining the shared file of the first user and the user key of the first user according to the URL and decrypting the shared file of the first user by using the user key of the first user comprises:

requesting, by the second user, the user key of the shared file of the first user corresponding to the URL from the trust center;

receiving a temporary URL and a temporary key sent by the trust center in response to the request, wherein the temporary key is a key through which the trust center re-encrypts the shared file of the first user that is obtained and decrypted to create a temporary file, wherein the temporary URL is a URL that is returned by the cloud server and corresponds to the temporary file, and wherein the temporary file is a file obtained by the trust center by re-encrypting the shared file of the first user that is obtained and decrypted;

obtaining the temporary file corresponding to the temporary URL from the cloud server; and

decrypting the temporary file by using the temporary key.

3. The method according to claim 2 , wherein, after receiving the URL, the second user can obtain the user key of the first user according to the URL and decrypt the shared file of the first user using the user key of the first user.

4. The method according to claim 2 , further comprising obtaining, by the second user, the user key of the first user according to the URL and decrypting the shared file of the first user using the user key of the first user.

5. The method according to claim 4 , wherein obtaining the shared file of the first user and the user key of the first user according to the URL and decrypting the shared file of the first user by using the user key of the first user comprises:

obtaining, by the second user, the user key of the shared file of the first user from the trust center;

obtaining the shared file of the first user from the cloud server according to the URL; and

decrypting the shared file of the first user by using the user key of the first user.

6. A data sharing device comprising:

a receiving unit configured to receive a request from a second user through a uniform resource locator (URL) for a user key of a shared file of a first user, wherein the second user is a legitimate user authorized by the first user through a trust center to access the shared file of the first user and the shared file of the first user is a shared file encrypted by using the user key of the first user;

an obtaining unit configured to obtain, according to the URL, a file description of the shared file of the first user from a cloud server, wherein the file description is a file description obtained by encrypting the user key of the first user by using a public key of the trust center, wherein the obtaining unit is further configured to, while obtaining the file description of the shared file of the first user from the cloud server, obtain the shared file of the first user corresponding to the URL, and wherein the data sharing device further comprises:

a decrypting unit configured to decrypt the file description by using a private key corresponding to the public key of the trust center to obtain the user key of the first user;

a second decrypting unit configured to decrypt the obtained shared file using the user key of the first user obtained by the decrypting unit to obtain an original shared file of the first user;

an encrypting unit configured to encrypt the original shared file using a temporary key to obtain a temporary file;

a sending unit, configured to send the user key of the first user to the second user;

a second sending unit configured to upload the temporary file to the cloud server; and

a second receiving unit configured to a temporary URL that is delivered by the cloud server and corresponds to the temporary file, wherein the sending unit is further configured to send the temporary URL and the temporary key to the second user.