Digital credentials are the digital equivalent of paper-based credentials. Just as a paper-based credential could be a passport, a driver's license, a membership certificate or some kind of ticket to obtain some service, such as a cinema ticket or a public transport ticket, a digital credential is a proof of qualification, competence, or clearance that is attached to a person. Also, digital credentials prove something about their owner. Both types of credentials may contain personal information such as the person's name, birthplace, birthdate, and/or biometric information such as a picture or a finger print.
Because of the still evolving, and sometimes conflicting, terminologies used in the fields of computer science, computer security, and cryptography, the term "digital credential" is used quite confusingly in these fields. Sometimes passwords or other means of authentication are referred to as credentials. In operating system design, credentials are the properties of a process (such as its effective UID) that is used for determining its access rights. On other occasions, certificates and associated key material such as those stored in PKCS#12 and PKCS#15 are referred to as credentials.
Digital badges are a form of digital credential that indicate an accomplishment, skill, quality or interest. Digital badges can be earned in a variety of learning environments.
Real world credentials are a diverse social phenomenon, and as such are difficult to define. As with digital signatures it is misleading to assume a direct correspondence between the real-world and the digital concept. This holds even if defining criteria for credentials in the digital world could be agreed on.
The success of digital signatures as a replacement for paper based signatures has lagged behind expectations. On the other hand, many unexpected uses of digital signatures were discovered by recent cryptographic research. A related insight that can be learned from digital signatures is that the cryptographic mechanism need not be confused with overall process that turns a digital signature into something that has more or less the same properties as a paper based signature. Electronic signatures such as paper signatures sent by fax may have legal meaning, while secure cryptographic signatures may serve completely different purposes. We need to distinguish the algorithm from the process.