1. A system for storing electronic documents in a secure and searchable manner, the system including a client portion and a server portion, the client portion being located at a trusted location and comprising: a parser to parse electronic documents received at the client portion to identify terms of interest within the received electronic document; a search and retrieval interface to specify one or more terms of interest to identify and retrieve one or more documents from the server portion; a first encryptor to encrypt identified terms of interest to obtain ciphertext versions of the terms of interest; a second encryptor to encrypt the received document to obtain a ciphertext version of the received document; a decryptor to decrypt a ciphertext version of a retrieved document to obtain a plaintext version; and client communications means to transfer the ciphertext version of the received document and the ciphertext version of the identified terms to the server portion and to receive a ciphertext version of documents from the server portion; and the server portion comprising: server communications means to receive from a client portion the ciphertext version of a document and the ciphertext version of identified terms and to transfer the ciphertext version of an identified document to the client portion; a storage device to store ciphertext versions of documents received from the client portion; an indexer and search engine to construct and maintain a searchable index of received ciphertext versions of identified terms contained in the ciphertext versions of documents received from the client portion and responsive to the search and retrieval interface of the client portion to cause the storage device and the server communications means to transfer ciphertext copies of the identified documents of interest to the client portion; an encryptor to encrypt ciphertext documents received at the server portion and to decrypt ciphertext documents to be transferred to the client portion; a retention manager operable to determine the relevant destruction date for each ciphertext document received at the server portion; and a retention key manager storing an encryption key for each destruction date of documents stored in the storage device, the retention key manager responsive to the retention manager to provide the encryption key for the relevant destruction date to the encryptor and to destroy encryption keys whose related destruction date has passed, wherein the retention manager compares one or more characteristics of each received ciphertext document to predefined criteria to determine the relevant destruction date for the received document; and a dictionary tool operable to maintain a list of the identified plaintext terms of interest for all documents received at the client portion and wherein wildcard terms specified at the search and retrieval interface are matched to terms in the maintained list, the matched terms being encrypted by the first encryptor.