<div class="content"><p>The BackupKey Remote Protocol is used by clients to encrypt
and decrypt sensitive data (such as cryptographic keys) with the help of a
server. Data encrypted using this protocol can be decrypted only by the server,
and the client can safely write such encrypted data to storage that is not
specially protected. In Windows, this protocol is used to provide <a href="32d60aa4-e40c-414a-986c-db731aca7e71#gt_8312d817-fdc5-4a49-8894-729b7b9e0ce5" data-linktype="relative-path">encryption</a> of user secrets
through the <a href="32d60aa4-e40c-414a-986c-db731aca7e71#gt_3af2be04-f627-4a02-a3b0-b465ccede53f" data-linktype="relative-path">Data Protection
Application Program Interface (DPAPI)</a> in an <a href="32d60aa4-e40c-414a-986c-db731aca7e71#gt_fcaec097-23d5-4b8f-b3e7-5739cc9c1d78" data-linktype="relative-path">Active Directory Domain</a>.</p><p>Familiarity with cryptography and <a href="32d60aa4-e40c-414a-986c-db731aca7e71#gt_fbe33f73-7a2c-4134-ab9e-7a12c6d01348" data-linktype="relative-path">Public Key Infrastructure (PKI)</a>
concepts (such as asymmetric and <a href="32d60aa4-e40c-414a-986c-db731aca7e71#gt_5d5fbe33-fb23-4288-bf7d-d8bd4593631c" data-linktype="relative-path">symmetric</a> cryptography,
digital <a href="32d60aa4-e40c-414a-986c-db731aca7e71#gt_7a0f4b71-23ba-434f-b781-28053ed64879" data-linktype="relative-path">certificate</a>
concepts, and cryptographic key exchange) is required for a complete
understanding of this specification. For more information about cryptography
and PKI concepts, see <a href="https://go.microsoft.com/fwlink/?LinkId=89841" data-linktype="external">[CRYPTO]</a>.</p><p>Sections 1.5, 1.8, 1.9, 2, and 3 of this specification are
normative. All other sections and examples in this specification are
informative.</p></div>