The Wide-Mouth Frog protocol
is a
computer network
A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...
authentication
Authentication (from ''authentikos'', "real, genuine", from αὐθέντης ''authentes'', "author") is the act of proving an assertion, such as the identity of a computer system user. In contrast with identification, the act of indicatin ...
protocol
Protocol may refer to:
Sociology and politics
* Protocol (politics), a formal agreement between nation states
* Protocol (diplomacy), the etiquette of diplomacy and affairs of state
* Etiquette, a code of personal behavior
Science and technolog ...
designed for use on insecure networks (the
Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
for example). It allows individuals communicating over a network to prove their identity to each other while also preventing eavesdropping or replay attacks, and provides for detection of modification and the prevention of unauthorized reading. This can be proven using Degano.
The protocol was first described under the name "The Wide-mouthed-frog Protocol" in the paper "A Logic of Authentication" (1990), which introduced
Burrows–Abadi–Needham logic Burrows–Abadi–Needham logic (also known as the BAN logic) is a set of rules for defining and analyzing information exchange protocols. Specifically, BAN logic helps its users determine whether exchanged information is trustworthy, secured agains ...
, and in which it was an "unpublished protocol ... proposed by" coauthor
Michael Burrows
Michael Burrows, FRS (born 1963) is a British computer scientist and the creator of the Burrows–Wheeler transform, currently working for Google. Born in Britain, as of 2018 he lives in the United States, although he remains a British citizen. ...
.
[ Burrows, Abadi, and Needham]
"A Logic of Authentication"
''ACM Transactions on Computer Systems'' 8 (1990), pp. 18–36. The paper gives no rationale for the protocol's whimsical name.
The protocol can be specified as follows in
security protocol notation
In cryptography, security (engineering) protocol notation, also known as protocol narrations and Alice & Bob notation, is a way of expressing a protocol of correspondence between entities of a dynamic system, such as a computer network. In the cont ...
:
[Wide Mouthed Frog](_blank)
''Security Protocols Open Repository''
* A, B, and S are identities of Alice, Bob, and the trusted server respectively
*
and
are
timestamp
A timestamp is a sequence of characters or encoded information identifying when a certain event occurred, usually giving date and time of day, sometimes accurate to a small fraction of a second. Timestamps do not have to be based on some absolut ...
s generated by A and S respectively
*
is a
symmetric key
Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both the encryption of plaintext and the decryption of ciphertext. The keys may be identical, or there may be a simple transformation to go between t ...
known only to A and S
*
is a generated symmetric key, which will be the
session key
A session key is a single-use symmetric key used for encrypting all messages in one communication session. A closely related term is content encryption key (CEK), traffic encryption key (TEK), or multicast key which refers to any key used for en ...
of the session between A and B
*
is a symmetric key known only to B and S
:
:
Note that to prevent active attacks, some form of authenticated encryption (or message authentication) must be used.
The protocol has several problems:
* A global clock is required.
* The server S has access to all keys.
* The value of the session key
is completely determined by ''A'', who must be competent enough to generate good keys.
* It can replay messages within the period when the timestamp is valid.
* ''A'' is not assured that ''B'' exists.
* The protocol is stateful. This is usually undesired because it requires more functionality and capability from the server. For example, ''S'' must be able to deal with situations in which ''B'' is unavailable.
See also
*
Alice and Bob
Alice and Bob are fictional characters commonly used as placeholders in discussions about cryptographic systems and protocols, and in other science and engineering literature where there are several participants in a thought experiment. The Al ...
*
Kerberos (protocol)
*
Needham–Schroeder protocol
The Needham–Schroeder protocol is one of the two key transport protocols intended for use over an insecure network, both proposed by Roger Needham and Michael Schroeder.
These are:
* The ''Needham–Schroeder Symmetric Key Protocol'', based on ...
*
Neuman–Stubblebine protocol
*
Otway–Rees protocol
The Otway–Rees protocol is a computer network authentication protocol designed for use on insecure networks (e.g. the Internet). It allows individuals communicating over such a network to prove their identity to each other while also preventing ...
*
Yahalom (protocol)
References
{{Reflist
Computer access control protocols