In cloud computing, the term zero-knowledge (or occasionally no-knowledge or zero access) refers to an online service that stores,

transfers Transfer may refer to: Arts and media * ''Transfer'' (2010 film), a German science-fiction movie directed by Damir Lukacevic and starring Zana Marjanović * ''Transfer'' (1966 film), a short film * ''Transfer'' (journal), in management studies ...

or manipulates data in a way that maintains a high level of confidentiality, where the data is only accessible to the data's owner (the client), and not to the service provider. This is achieved by encrypting the raw data at the client's side or

end-to-end End-to-end or End to End may refer to: * End-to-end auditable voting systems, a voting system * End-to-end delay, the time for a packet to be transmitted across a network from source to destination * End-to-end encryption, a cryptographic paradigm ...

(in case there is more than one client), without disclosing the password to the service provider. This means that neither the service provider, nor any third party that might intercept the data, can decrypt and access the data without prior permission, allowing the client a higher degree of

privacy Privacy (, ) is the ability of an individual or group to seclude themselves or information about themselves, and thereby express themselves selectively. The domain of privacy partially overlaps with security, which can include the concepts of a ...

than would otherwise be possible. In addition, zero-knowledge services often strive to hold as little

metadata Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive metadata – the descriptive ...

as possible, holding only that data that is functionally needed by the service. The term "zero-knowledge" was popularized by

backup In information technology, a backup, or data backup is a copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event. The verb form, referring to the process of doing so, is "back up", w ...

service

SpiderOak SpiderOak is a US-based collaboration tool, online backup and file hosting service that allows users to access, synchronize and share data using a cloud-based server, offered by a company of the same name. Its first offering, its online backup se ...

, which later switched to using the term "no knowledge" to avoid confusion with the computer science concept of zero-knowledge proof. Providers of zero-knowledge services include: *

Bitwarden Bitwarden is a freemium open-source software, open-source Password manager, password management service that stores sensitive information such as website credentials in an Encryption, encrypted vault. The platform offers a variety of client appl ...

* Cubbit * DekkoSecure * LucidLink *

NordLocker NordLocker is a file encryption software integrated with end-to-end encrypted cloud storage. It is available on Windows and macOS. NordLocker is developed by Nord Security, a company behind the NordVPN virtual private network, and is based in t ...

NordPass NordPass is a proprietary password manager launched in 2019. It is meant to help its users to organise their passwords and secure notes, keeping them in a single place — an encrypted password vault. This service comes in both free and premium vers ...

* ProtonMail * Signal *

* Sync.com * Tarsnap *

Skiff (email service) Skiff is an email service startup company and collaboration tool, that provides privacy-friendly end-to-end encrypted ''Email'' and ''Cloud services''. The company's commercial strategy is focused in offering to its clients a Source-Availabl ...

Tresorit Tresorit is a cloud storage service with end-to-end encryption. Founded in 2011, Tresorit closed an €11.5M Series B financing round in 2018 and was featured on FT1000 by Financial Times 2020 as the fifth fastest-growing cybersecurity company i ...

Memento Cloud

Disadvantages

Most

cloud storage Cloud storage is a model of computer data storage in which the digital data is stored in logical pools, said to be on "the cloud". The physical storage spans multiple servers (sometimes in multiple locations), and the physical environment is t ...

services keep a copy of the client's password on their servers, allowing clients who have lost their passwords to retrieve and decrypt their data using alternative means of authentication; but since zero-knowledge services ''do not'' store copies of clients' passwords, if a client loses their password then their data cannot be decrypted, making it practically unrecoverable. Most

services are also able to furnish access requests from law enforcement agencies for similar reasons; zero-knowledge services, however, are unable to do so, since their systems are designed to make clients' data inaccessible without the client's explicit cooperation.

References

{{reflist, * * * {{Cite news , last=Farivar , first=Cyrus , date=2016-10-04 , title=FBI demands Signal user data, but there's not much to hand over , language=en-us , work=Ars Technica , url=https://arstechnica.com/tech-policy/2016/10/fbi-demands-signal-user-data-but-theres-not-much-to-hand-over/ , access-date=2021-05-29 Privacy Computer security Backup software Secure communication Internet terminology