P. Devaki and G.Rghavendra Rao, The National Institute of Engg.,India

If a secret key or a password is to be used in an application, where multi users are involved, then itis better to share the key or the password to all the authorized users in such a way that a minimum or all the shares of the users put together must result in the key or the password. This method avoids the unauthorized access to the information by a single user with out the knowledge of the other users. So this can protect the important information and also protect the key by sharing. If the key is not shared, then always there may be a threat of key being compromised intentionally or unintentionally. If the key is shared among the authorized users, at the time of requirement to use the information, few authorized users can use their shares to reconstruct the key and use it. This avoids the drawbacks of the single user having the key. Also it is necessary to authenticate the shares given by the users during reconstruction of the key. This facilitates the verification of the modified shares or fake shares sent by the authorized or unauthorized users. To achieve the confidentiality of the key we are using the threshold secret sharing method where the key will be divided in to number of shares depending on the number of authorized users and represent those shares in Braille format, and to provide authentication we are using SHA-1 algorithm. The key can be text data, image.

Authentication, Braille format, Bitmap image, Confidentiality, Multiple keys, Secret key, Secret sharing.