The British Library is to secure the integrity of its National Digital Library by authenticating electronic documents and other materials.

The library is expected to amass up to 300 terabytes of content over the next five years including digitised versions of centuries-old manuscripts, digital journals and web archives.

A document sealing engine from vendor nCipher is being used to timestamp and digitally sign every item stored in the library to prove they have not been modified from the original.

The nCipher DSE200 system for electronic signatures seals digital material by providing an audit trail of both the document author and the document content.

A secure timestamp and time-based audit trail validates the authenticity of documents so that any tampering can be detected.

Sean Martin, head of architecture and development at the British Library, said: ‘With a book you can look at things like the chemical composition of the ink for authenticity, but a PDF in a file server could have been through the hands of over 20 administrators.

'As custodians of UK intellectual property, the point of time stamping digital items is about authenticity. If something is changed, the signature won’t match.’

The Legal Deposit Libraries Act of 2003 requires that UK electronic publications are deposited in the Library, and although it is already digitizing material from print and audio publishers, the pace will quicken when the legislation kicks in.

‘As the pendulum swings from publishing in print to more and more digital publishing the system is fundamental for long-term authenticity,’ said Martin.