Abstract: A method for inferring device fingerprint, performed by a processor, includes: obtaining a current device dataset including current device features from a user interface operating on a user device, when the current device dataset further includes a current protocol address and a device fingerprint pointer table does not include a current number of a target device fingerprint pointer corresponding to the current protocol address, obtaining a history protocol address, first history device features and first history number of the target device fingerprint pointer, when the current protocol address matches the history protocol address and the current device features matches the first history device features, using one first history number as the current number, and when the current protocol address does not match the history protocol address and the current device features matches the first history device features, setting the current number to point to a new device fingerprint.

Abstract: In a data encryption method, a request to input an encryption password set is made upon receipt of an encryption request to encrypt data, and the data are encrypted such that the encrypted data can be decrypted using one of the encryption password set and a predetermined supervisor password set upon receipt of the encryption password set. Thus, during decryption, one of the encryption password set and the supervisor password set can be used for decryption, thereby providing a restoring mechanism.

Abstract: In an e-mail encryption/decryption method, an e-mail encryption process is executed at a sending end before sending an e-mailmessagetoareceivingend. The e-mail encryption process is includes providing an e-mail message having a header and text, requesting selection of at least one portion of the text and decision of a password set corresponding to the selected portion, and encrypting the selected portion into an encrypted text region to be decrypted using the password set before sending the e-mail message to the receiving end upon receipt of a sending request. The header, encrypted text region and non-selected text portion of the e-mail message are timely displayed when the receiving end receives the e-mail message. Thus, the sending end can select to encrypt an e-mail message in part to facilitate use.