Secure and searchable storage system and method

A method of securely storing electronic documents in a secure and searchable manner, comprising the steps of:

• at a trusted location, receiving copies of electronic documents to be stored;
• parsing the received copies to identify terms of interest in the documents;
• validating at the client portion an encryption key to be used to encrypt the received copies of electronic documents by:
• (a) retrieving from the server portion a validation data set comprising plaintext test data, a ciphertext version of the plaintext test data previously encrypted with the key to be validated, and a digital signature for each of the plaintext test data and ciphertext version of the plaintext data;
• (b) determining a digital signature for the plaintext test data and comparing the determined digital signature to the retrieved digital signature for the plaintext data set to determine if the plaintext data set has been corrupted and determining a digital signature for the cyphertext version of the plaintext test data and comparing the determined digital signature to the retrieved digital signature for the cyphertext version of the plaintext data set to determine if the cyphertext version of the plaintext data set has been corrupted;
• (c) if either or both or both of the plaintext data set and the cyphertext version of the plaintext data set has been corrupted, performing steps (a) and (b) again to obtain an uncorrupted validation data set;
• and
• (d) encrypting the plaintext data set with the encryption key to be validated and comparing the resulting cyphertext version of the plaintext data set to the ciphertext version of the plaintext data set in the retrieved uncorrupted validation data set and deeming the encryption key to be valid if the encrypted the plaintext data set is identical to the ciphertext version of the plaintext data set in the retrieved uncorrupted validation data set and otherwise deeming the encryption key to be invalid;
• encrypting the received documents to obtain ciphertext versions of the received documents and encrypting the identified terms of interest found in each document to obtain ciphertext copies of the terms;
• transferring the ciphertext copies of the documents and identified terms to a second location over a communications link;
• receiving the ciphertext copies of the documents at the second location and storing received ciphertext copies on a storage device;
• receiving the ciphertext copies of the identified terms of interest at the second location and constructing and maintaining an index which indicates, for each received ciphertext term of interest, the storage location of each ciphertext copy of the documents which contains the term of interest;
• providing a search interface at the trusted location wherein a user can search for a stored ciphertext copy of a document stored on the storage device by defining a query containing one or more plaintext terms of interest, the plaintext terms of interest being encrypted and, over the communications link, being compared to the ciphertext terms in the index to identify the ciphertext copies of documents stored on the storage device;
• transmitting the identified ciphertext copies of documents over the communications link to the trusted location and decrypting the transmitted ciphertext copies of the documents at the trusted location to obtain plaintext copies of the identified documents;
• and
• using a dictionary tool to maintain a list of identified terms of interest at the trusted location and accepting queries at the search interface including one or more wildcard operators and examining the maintained list of identified terms of interest to expanding the wildcard operators in the query.