Password

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A password field in a sign in form.

A password, sometimes called a passcode,[1] is a memorized secret, typically a string

of characters, usually used to confirm a user's identity. [2] Using the terminology of the
NIST Digital Identity Guidelines,[3] the secret is memorized by a party called
the claimant while the party verifying the identity of the claimant is called the verifier.
When the claimant successfully demonstrates knowledge of the password to the verifier
through an established authentication protocol,[4] the verifier is able to infer the
claimant's identity.
In general, a password is an arbitrary string of characters including letters, digits, or
other symbols. If the permissible characters are constrained to be numeric, the
corresponding secret is sometimes called a personal identification number (PIN).
Despite its name, a password does not need to be an actual word; indeed, a non-word
(in the dictionary sense) may be harder to guess, which is a desirable property of
passwords. A memorized secret consisting of a sequence of words or other text
separated by spaces is sometimes called a passphrase. A passphrase is similar to a
password in usage, but the former is generally longer for added security. [5]

Contents

 1History
 2Choosing a secure and memorable password
 3Factors in the security of a password system
o 3.1Rate at which an attacker can try guessed passwords
o 3.2Limits on the number of password guesses
o 3.3Form of stored passwords
o 3.4Methods of verifying a password over a network
 3.4.1Simple transmission of the password
  3.4.2Transmission through encrypted channels
 3.4.3Hash-based challenge-response methods
 3.4.4Zero-knowledge password proofs
o 3.5Procedures for changing passwords
o 3.6Password longevity
o 3.7Number of users per password
o 3.8Password security architecture
o 3.9Password reuse
o 3.10Writing down passwords on paper
o 3.11After death
o 3.12Multi-factor authentication
 4Password rules
 5Password cracking
o 5.1Incidents
 6Alternatives to passwords for authentication
 7"The Password is dead"
 8See also
 9References
 10External links

History[edit]
Passwords have been used since ancient times. Sentries would challenge those
wishing to enter an area to supply a password or watchword, and would only allow a
person or group to pass if they knew the password. Polybius describes the system for
the distribution of watchwords in the Roman military as follows:
The way in which they secure the passing round of the watchword for the night is as
follows: from the tenth maniple of each class of infantry and cavalry, the maniple which
is encamped at the lower end of the street, a man is chosen who is relieved from guard
duty, and he attends every day at sunset at the tent of the tribune, and receiving from
him the watchword—that is a wooden tablet with the word inscribed on it – takes his
leave, and on returning to his quarters passes on the watchword and tablet before
witnesses to the commander of the next maniple, who in turn passes it to the one next
him. All do the same until it reaches the first maniples, those encamped near the tents
of the tribunes. These latter are obliged to deliver the tablet to the tribunes before dark.
So that if all those issued are returned, the tribune knows that the watchword has been
given to all the maniples, and has passed through all on its way back to him. If any one
of them is missing, he makes inquiry at once, as he knows by the marks from what
quarter the tablet has not returned, and whoever is responsible for the stoppage meets
with the punishment he merits.[6]
Passwords in military use evolved to include not just a password, but a password and a
counterpassword; for example in the opening days of the Battle of Normandy,
paratroopers of the U.S. 101st Airborne Division used a password—flash—which was
presented as a challenge, and answered with the correct response—thunder. The
challenge and response were changed every three days. American paratroopers also
famously used a device known as a "cricket" on D-Day in place of a password system
as a temporarily unique method of identification; one metallic click given by the device in
lieu of a password was to be met by two clicks in reply. [7]
Passwords have been used with computers since the earliest days of computing.
The Compatible Time-Sharing System (CTSS), an operating system introduced
at MIT in 1961, was the first computer system to implement password login. [8][9] CTSS
had a LOGIN command that requested a user password. "After typing PASSWORD, the
system turns off the printing mechanism, if possible, so that the user may type in his
password with privacy."[10] In the early 1970s, Robert Morris developed a system of
storing login passwords in a hashed form as part of the Unix operating system. The
system was based on a simulated Hagelin rotor crypto machine, and first appeared in
6th Edition Unix in 1974. A later version of his algorithm, known as crypt(3), used a 12-
bit salt and invoked a modified form of the DES algorithm 25 times to reduce the risk of
pre-computed dictionary attacks.[11]
In modern times, user names and passwords are commonly used by people during
a log in process that controls access to protected computer operating systems, mobile
phones, cable TV decoders, automated teller machines (ATMs), etc. A typical computer
user has passwords for many purposes: logging into accounts, retrieving e-mail,
accessing applications, databases, networks, web sites, and even reading the morning
newspaper online.

Choosing a secure and memorable password [edit]

The easier a password is for the owner to remember generally means it will be easier
for an attacker to guess.[12] However, passwords that are difficult to remember may also
reduce the security of a system because (a) users might need to write down or
electronically store the password, (b) users will need frequent password resets and (c)
users are more likely to re-use the same password across different accounts. Similarly,
the more stringent the password requirements, such as "have a mix of uppercase and
lowercase letters and digits" or "change it monthly", the greater the degree to which
users will subvert the system.[13] Others argue longer passwords provide more security
(e.g., entropy) than shorter passwords with a wide variety of characters. [14]
In The Memorability and Security of Passwords,[15] Jeff Yan et al. examine the effect of
advice given to users about a good choice of password. They found that passwords
based on thinking of a phrase and taking the first letter of each word are just as
memorable as naively selected passwords, and just as hard to crack as randomly
generated passwords.
Combining two or more unrelated words and altering some of the letters to special
characters or numbers is another good method, [16] but a single dictionary word is not.
Having a personally designed algorithm for generating obscure passwords is another
good method.[citation needed]
However, asking users to remember a password consisting of a "mix of uppercase and
lowercase characters" is similar to asking them to remember a sequence of bits: hard to
remember, and only a little bit harder to crack (e.g. only 128 times harder to crack for 7-
letter passwords, less if the user simply capitalises one of the letters). Asking users to
use "both letters and digits" will often lead to easy-to-guess substitutions such as 'E' →
'3' and 'I' → '1', substitutions which are well known to attackers. Similarly typing the
password one keyboard row higher is a common trick known to attackers. [17]
In 2013, Google released a list of the most common password types, all of which are
considered insecure because they are too easy to guess (especially after researching
an individual on social media):[18]

 The name of a pet, child, family member, or significant

other
 Anniversary dates and birthdays
 Birthplace
 Name of a favorite holiday
 Something related to a favorite sports team
 The word "password"

Factors in the security of a password system [edit]

The security of a password-protected system depends on several factors. The overall
system must be designed for sound security, with protection against computer
viruses, man-in-the-middle attacks and the like. Physical security issues are also a
concern, from deterring shoulder surfing to more sophisticated physical threats such as
video cameras and keyboard sniffers. Passwords should be chosen so that they are
hard for an attacker to guess and hard for an attacker to discover using any of the
available automatic attack schemes. See password strength and computer security for
more information.
Nowadays, it is a common practice for computer systems to hide passwords as they are
typed. The purpose of this measure is to prevent bystanders from reading the
password; however, some argue that this practice may lead to mistakes and stress,
encouraging users to choose weak passwords. As an alternative, users should have the
option to show or hide passwords as they type them.[19]
Effective access control provisions may force extreme measures on criminals seeking to
acquire a password or biometric token. [20] Less extreme measures
include extortion, rubber hose cryptanalysis, and side channel attack.
Some specific password management issues that must be considered when thinking
about, choosing, and handling, a password follow.
Rate at which an attacker can try guessed passwords[edit]
The rate at which an attacker can submit guessed passwords to the system is a key
factor in determining system security. Some systems impose a time-out of several
seconds after a small number (e.g., three) of failed password entry attempts. In the
absence of other vulnerabilities, such systems can be effectively secure with relatively
simple passwords, if they have been well chosen and are not easily guessed. [21]
Many systems store a cryptographic hash of the password. If an attacker gets access to
the file of hashed passwords guessing can be done offline, rapidly testing candidate
passwords against the true password's hash value. In the example of a web-server, an
online attacker can guess only at the rate at which the server will respond, while an off-
line attacker (who gains access to the file) can guess at a rate limited only by the
hardware on which the attack is running.
Passwords that are used to generate cryptographic keys (e.g., for disk encryption or Wi-
Fi security) can also be subjected to high rate guessing. Lists of common passwords
are widely available and can make password attacks very efficient. (See Password
cracking.) Security in such situations depends on using passwords or passphrases of
adequate complexity, making such an attack computationally infeasible for the attacker.
Some systems, such as PGP and Wi-Fi WPA, apply a computation-intensive hash to
the password to slow such attacks. See key stretching.
Limits on the number of password guesses[edit]
An alternative to limiting the rate at which an attacker can make guesses on a password
is to limit the total number of guesses that can be made. The password can be disabled,
requiring a reset, after a small number of consecutive bad guesses (say 5); and the user
may be required to change the password after a larger cumulative number of bad
guesses (say 30), to prevent an attacker from making an arbitrarily large number of bad
guesses by interspersing them between good guesses made by the legitimate
password owner.[22] Attackers may conversely use knowledge of this mitigation to
implement a denial of service attack against the user by intentionally locking the user
out of their own device; this denial of service may open other avenues for the attacker to
manipulate the situation to their advantage via social engineering.
Form of stored passwords[edit]
Some computer systems store user passwords as plaintext, against which to compare
user logon attempts. If an attacker gains access to such an internal password store, all
passwords—and so all user accounts—will be compromised. If some users employ the
same password for accounts on different systems, those will be compromised as well.
More secure systems store each password in a cryptographically protected form, so
access to the actual password will still be difficult for a snooper who gains internal
access to the system, while validation of user access attempts remains possible. The
most secure don't store passwords at all, but a one-way derivation, such as
a polynomial, modulus, or an advanced hash function.[14] Roger Needham invented the
now common approach of storing only a "hashed" form of the plaintext password. [23]
[24]
 When a user types in a password on such a system, the password handling software
runs through a cryptographic hash algorithm, and if the hash value generated from the
user's entry matches the hash stored in the password database, the user is permitted
access. The hash value is created by applying a cryptographic hash function to a string
consisting of the submitted password and, in many implementations, another value
known as a salt. A salt prevents attackers from easily building a list of hash values for
common passwords and prevents password cracking efforts from scaling across all
users.[25] MD5 and SHA1 are frequently used cryptographic hash functions but they are
not recommended for password hashing unless they are used as part of a larger
construction such as in PBKDF2.[26]
The stored data—sometimes called the "password verifier" or the "password hash"—is
often stored in Modular Crypt Format or RFC 2307 hash format, sometimes in
the /etc/passwd file or the /etc/shadow file.[27]
The main storage methods for passwords are plain text, hashed, hashed and salted,
and reversibly encrypted.[28] If an attacker gains access to the password file, then if it is
stored as plain text, no cracking is necessary. If it is hashed but not salted then it is
vulnerable to rainbow table attacks (which are more efficient than cracking). If it is
reversibly encrypted then if the attacker gets the decryption key along with the file no
cracking is necessary, while if he fails to get the key cracking is not possible. Thus, of
the common storage formats for passwords only when passwords have been salted and
hashed is cracking both necessary and possible.[28]
If a cryptographic hash function is well designed, it is computationally infeasible to
reverse the function to recover a plaintext password. An attacker can, however, use
widely available tools to attempt to guess the passwords. These tools work by hashing
possible passwords and comparing the result of each guess to the actual password
hashes. If the attacker finds a match, they know that their guess is the actual password
for the associated user. Password cracking tools can operate by brute force (i.e. trying
every possible combination of characters) or by hashing every word from a list; large
lists of possible passwords in many languages are widely available on the Internet.
[14]
 The existence of password cracking tools allows attackers to easily recover poorly
chosen passwords. In particular, attackers can quickly recover passwords that are
short, dictionary words, simple variations on dictionary words or that use easily
guessable patterns.[29] A modified version of the DES algorithm was used as the basis for
the password hashing algorithm in early Unix systems.[30] The crypt algorithm used a 12-
bit salt value so that each user's hash was unique and iterated the DES algorithm 25
times in order to make the hash function slower, both measures intended to frustrate
automated guessing attacks.[30] The user's password was used as a key to encrypt a
fixed value. More recent Unix or Unix like systems (e.g., Linux or the
various BSD systems) use more secure password hashing algorithms such
as PBKDF2, bcrypt, and scrypt which have large salts and an adjustable cost or number
of iterations.[31] A poorly designed hash function can make attacks feasible even if a
strong password is chosen. See LM hash for a widely deployed, and insecure, example.
[32]

Methods of verifying a password over a network[edit]

Simple transmission of the password[edit]
Passwords are vulnerable to interception (i.e., "snooping") while being transmitted to the
authenticating machine or person. If the password is carried as electrical signals on
unsecured physical wiring between the user access point and the central system
controlling the password database, it is subject to snooping by wiretapping methods. If it
is carried as packeted data over the Internet, anyone able to watch
the packets containing the logon information can snoop with a very low probability of
detection.
Email is sometimes used to distribute passwords but this is generally an insecure
method. Since most email is sent as plaintext, a message containing a password is
readable without effort during transport by any eavesdropper. Further, the message will
be stored as plaintext on at least two computers: the sender's and the recipient's. If it
passes through intermediate systems during its travels, it will probably be stored on
there as well, at least for some time, and may be copied to backup, cache or history
files on any of these systems.
Using client-side encryption will only protect transmission from the mail handling system
server to the client machine. Previous or subsequent relays of the email will not be
protected and the email will probably be stored on multiple computers, certainly on the
originating and receiving computers, most often in clear text.
Transmission through encrypted channels[edit]
The risk of interception of passwords sent over the Internet can be reduced by, among
other approaches, using cryptographic protection. The most widely used is
the Transport Layer Security (TLS, previously called SSL) feature built into most current
Internet browsers. Most browsers alert the user of a TLS/SSL protected exchange with
a server by displaying a closed lock icon, or some other sign, when TLS is in use. There
are several other techniques in use; see cryptography.
Hash-based challenge-response methods[edit]
Unfortunately, there is a conflict between stored hashed-passwords and hash-
based challenge-response authentication; the latter requires a client to prove to a server
that they know what the shared secret (i.e., password) is, and to do this, the server must
be able to obtain the shared secret from its stored form. On many systems
(including Unix-type systems) doing remote authentication, the shared secret usually
becomes the hashed form and has the serious limitation of exposing passwords to
offline guessing attacks. In addition, when the hash is used as a shared secret, an
attacker does not need the original password to authenticate remotely; they only need
the hash.
Zero-knowledge password proofs[edit]
Rather than transmitting a password, or transmitting the hash of the
password, password-authenticated key agreement systems can perform a zero-
knowledge password proof, which proves knowledge of the password without exposing
it.
Moving a step further, augmented systems for password-authenticated key
agreement (e.g., AMP, B-SPEKE, PAK-Z, SRP-6) avoid both the conflict and limitation
of hash-based methods. An augmented system allows a client to prove knowledge of
the password to a server, where the server knows only a (not exactly) hashed
password, and where the unhashed password is required to gain access.
Procedures for changing passwords[edit]
Usually, a system must provide a way to change a password, either because a user
believes the current password has been (or might have been) compromised, or as a
precautionary measure. If a new password is passed to the system in unencrypted form,
security can be lost (e.g., via wiretapping) before the new password can even be
installed in the password database and if the new password is given to a compromised
employee, little is gained. Some web sites include the user-selected password in an
unencrypted confirmation e-mail message, with the obvious increased vulnerability.
Identity management systems are increasingly used to automate issuance of
replacements for lost passwords, a feature called self service password reset. The
user's identity is verified by asking questions and comparing the answers to ones
previously stored (i.e., when the account was opened).
Some password reset questions ask for personal information that could be found on
social media, such as mother's maiden name. As a result, some security experts
recommend either making up one's own questions or giving false answers. [33]
Password longevity[edit]
"Password aging" is a feature of some operating systems which forces users to change
passwords frequently (e.g., quarterly, monthly or even more often). Such policies
usually provoke user protest and foot-dragging at best and hostility at worst. There is
often an increase in the people who note down the password and leave it where it can
easily be found, as well as help desk calls to reset a forgotten password. Users may use
simpler passwords or develop variation patterns on a consistent theme to keep their
passwords memorable.[34] Because of these issues, there is some debate as to whether
password aging is effective.[35] Changing a password will not prevent abuse in most
cases, since the abuse would often be immediately noticeable. However, if someone
may have had access to the password through some means, such as sharing a
computer or breaching a different site, changing the password limits the window for
abuse.[36]
Number of users per password[edit]
Allotting separate passwords to each user of a system is preferable to having a single
password shared by legitimate users of the system, certainly from a security viewpoint.
This is partly because users are more willing to tell another person (who may not be
authorized) a shared password than one exclusively for their use. [citation needed] Single
passwords are also much less convenient to change because many people need to be
told at the same time, and they make removal of a particular user's access more
difficult, as for instance on graduation or resignation. Separate logins are also often
used for accountability, for example to know who changed a piece of data.
Password security architecture[edit]
Common techniques used to improve the security of computer systems protected by a
password include:

 Not displaying the password on the display screen as it is

being entered or obscuring it as it is typed by using
asterisks (*) or bullets (•).
 Allowing passwords of adequate length.
(Some legacy operating systems, including early
versions[which?] of Unix and Windows, limited passwords to an
8 character maximum,[37][38][39] reducing security.)
  Requiring users to re-enter their password after a period of
inactivity (a semi log-off policy).
 Enforcing a password policy to increase password
strength and security.
o Assigning randomly chosen passwords.
o Requiring minimum password lengths.[26]
o Some systems require characters from various
character classes in a password—for example, "must
have at least one uppercase and at least one lowercase
letter". However, all-lowercase passwords are more
secure per keystroke than mixed capitalization
passwords.[40]
o Employ a password blacklist to block the use of weak,
easily guessed passwords
o Providing an alternative to keyboard entry (e.g., spoken
passwords, or biometric identifiers).
o Requiring more than one authentication system, such
as two-factor authentication (something a user has and
something the user knows).
 Using encrypted tunnels or password-authenticated key
agreement to prevent access to transmitted passwords via
network attacks
 Limiting the number of allowed failures within a given time
period (to prevent repeated password guessing). After the
limit is reached, further attempts will fail (including correct
password attempts) until the beginning of the next time
period. However, this is vulnerable to a form of denial of
service attack.
 Introducing a delay between password submission
attempts to slow down automated password guessing
programs.
Some of the more stringent policy enforcement measures can pose a risk of alienating
users, possibly decreasing security as a result.
Password reuse[edit]
It is common practice amongst computer users to reuse the same password on multiple
sites. This presents a substantial security risk, because an attacker needs to only
compromise a single site in order to gain access to other sites the victim uses. This
problem is exacerbated by also reusing usernames, and by websites requiring email
logins, as it makes it easier for an attacker to track a single user across multiple sites.
Password reuse can be avoided or minimised by using mnemonic techniques, writing
passwords down on paper, or using a password manager.[41]
It has been argued by Redmond researchers Dinei Florencio and Cormac Herley,
together with Paul C. van Oorschot of Carleton University, Canada, that password reuse
is inevitable, and that users should reuse passwords for low-security websites (which
contain little personal data and no financial information, for example) and instead focus
their efforts on remember long, complex passwords for a few important accounts, such
as bank accounts.[42] Similar arguments were made by Forbes in not change passwords
as often as many "experts" advise, due to the same limitations in human memory. [34]
Writing down passwords on paper[edit]
Historically, many security experts asked people to memorize their passwords: "Never
write down a password". More recently, many security experts such as Bruce
Schneier recommend that people use passwords that are too complicated to memorize,
write them down on paper, and keep them in a wallet. [43][44][45][46][47][48][49]
Password manager software can also store passwords relatively safely, in an encrypted
file sealed with a single master password.
After death[edit]
According to a survey by the University of London, one in ten people are now leaving
their passwords in their wills to pass on this important information when they die. One
third of people, according to the poll, agree that their password protected data is
important enough to pass on in their will.[50]
Multi-factor authentication[edit]
Main article: Multi-factor authentication
Multi-factor authentication schemes combine passwords (as "knowledge factors") with
one or more other means of authentication, to make authentication more secure and
less vulnerable to compromised passwords. For example, a simple two-factor login
might send a text message, e-mail, automated phone call, or similar alert whenever a
login attempt is made, possibly supplying a code which must be entered in addition to a
password.[51] More sophisticated factors include such things as hardware tokens and
biometric security.

Password rules[edit]
Further information: Password policy
Most organizations specify a password policy that sets requirements for the composition
and usage of passwords, typically dictating minimum length, required categories (e.g.,
upper and lower case, numbers, and special characters), prohibited elements (e.g., use
of one's own name, date of birth, address, telephone number). Some governments have
national authentication frameworks[52] that define requirements for user authentication to
government services, including requirements for passwords.
Many websites enforce standard rules such as minimum and maximum length, but also
frequently include composition rules such as featuring at least one capital letter and at
least one number/symbol. These latter, more specific rules were largely based on a
2003 report by the National Institute of Standards and Technology (NIST), authored by
Bill Burr.[53] It originally proposed the practice of using numbers, obscure characters and
capital letters and updating regularly. In a 2017 Wall Street Journal article, Burr reported
he regrets these proposals and made a mistake when he recommended them. [54]
According to a 2017 rewrite of this NIST report, many websites have rules that actually
have the opposite effect on the security of their users. This includes complex
composition rules as well as forced password changes after certain periods of time.
While these rules have long been widespread, they have also long been seen as
annoying and ineffective by both users and cyber-security experts. [55] The NIST
recommends people use longer phrases as passwords (and advises websites to raise
the maximum password length) instead of hard-to-remember passwords with "illusory
complexity" such as "pA55w+rd".[56] A user prevented from using the password
"password" may simply choose "Password1" if required to include a number and
uppercase letter. Combined with forced periodic password changes, this can lead to
passwords that are difficult to remember but easy to crack. [53]
Paul Grassi, one of the 2017 NIST report's authors, further elaborated: "Everyone
knows that an exclamation point is a 1, or an I, or the last character of a password. $ is
an S or a 5. If we use these well-known tricks, we aren’t fooling any adversary. We are
simply fooling the database that stores passwords into thinking the user did something
good."[55]
Pieris Tsokkis and Eliana Stavrou were able to identify some bad password construction
strategies through their research and development of a password generator tool. They
came up with eight categories of password construction strategies based on exposed
password lists, password cracking tools, and online reports citing the most used
passwords. These categories include user-related information, keyboard combinations
and patterns, placement strategy, word processing, substitution, capitalization, append
dates, and a combination of the previous categories [57]

Password cracking[edit]
Main article: Password cracking
Attempting to crack passwords by trying as many possibilities as time and money permit
is a brute force attack. A related method, rather more efficient in most cases, is
a dictionary attack. In a dictionary attack, all words in one or more dictionaries are
tested. Lists of common passwords are also typically tested.
Password strength is the likelihood that a password cannot be guessed or discovered,
and varies with the attack algorithm used. Cryptologists and computer scientists often
refer to the strength or 'hardness' in terms of entropy.[14]
Passwords easily discovered are termed weak or vulnerable; passwords very difficult or
impossible to discover are considered strong. There are several programs available for
password attack (or even auditing and recovery by systems personnel) such
as L0phtCrack, John the Ripper, and Cain; some of which use password design
vulnerabilities (as found in the Microsoft LANManager system) to increase efficiency.
These programs are sometimes used by system administrators to detect weak
passwords proposed by users.
Studies of production computer systems have consistently shown that a large fraction of
all user-chosen passwords are readily guessed automatically. For example, Columbia
University found 22% of user passwords could be recovered with little effort. [58] According
to Bruce Schneier, examining data from a 2006 phishing attack, 55%
of MySpace passwords would be crackable in 8 hours using a commercially available
Password Recovery Toolkit capable of testing 200,000 passwords per second in 2006.
[59]
 He also reported that the single most common password was password1, confirming
yet again the general lack of informed care in choosing passwords among users. (He
nevertheless maintained, based on these data, that the general quality of passwords
has improved over the years—for example, average length was up to eight characters
from under seven in previous surveys, and less than 4% were dictionary words. [60])
Incidents[edit]

 On July 16, 1998, CERT reported an incident where an

attacker had found 186,126 encrypted passwords. At the
time the attacker was discovered, 47,642 passwords had
already been cracked.[61]
 In September, 2001, after the deaths of 960 New York
employees in the September 11 attacks, financial services
firm Cantor Fitzgerald through Microsoft broke the
passwords of deceased employees to gain access to files
needed for servicing client accounts. [62] Technicians used
brute-force attacks, and interviewers contacted families to
gather personalized information that might reduce the
search time for weaker passwords.[62]
 In December 2009, a major password breach of
the Rockyou.com website occurred that led to the release
of 32 million passwords. The hacker then leaked the full list
of the 32 million passwords (with no other identifiable
information) to the Internet. Passwords were stored in
cleartext in the database and were extracted through a
SQL injection vulnerability. The Imperva Application
Defense Center (ADC) did an analysis on the strength of
the passwords.[63]
 In June, 2011, NATO (North Atlantic Treaty Organization)
experienced a security breach that led to the public release
of first and last names, usernames, and passwords for
more than 11,000 registered users of their e-bookshop.
The data was leaked as part of Operation AntiSec, a
movement that includes Anonymous, LulzSec, as well as
other hacking groups and individuals. The aim of AntiSec is
to expose personal, sensitive, and restricted information to
the world, using any means necessary.[64]
 On July 11, 2011, Booz Allen Hamilton, a consulting firm
that does work for the Pentagon, had their servers hacked
 by Anonymous and leaked the same day. "The leak,
dubbed 'Military Meltdown Monday,' includes 90,000 logins
of military personnel—including personnel
from USCENTCOM, SOCOM, the Marine corps, various Air
Force facilities, Homeland Security, State Department staff,
and what looks like private sector contractors." [65] These
leaked passwords wound up being hashed in SHA1, and
were later decrypted and analyzed by the ADC team
at Imperva, revealing that even military personnel look for
shortcuts and ways around the password requirements. [66]

Alternatives to passwords for authentication[edit]

The numerous ways in which permanent or semi-permanent passwords can be
compromised has prompted the development of other techniques. Unfortunately, some
are inadequate in practice, and in any case few have become universally available for
users seeking a more secure alternative. [citation needed] A 2012 paper[67] examines why
passwords have proved so hard to supplant (despite numerous predictions that they
would soon be a thing of the past[68]); in examining thirty representative proposed
replacements with respect to security, usability and deployability they conclude "none
even retains the full set of benefits that legacy passwords already provide."

 Single-use passwords. Having passwords which are only

valid once makes many potential attacks ineffective. Most
users find single use passwords extremely inconvenient.
They have, however, been widely implemented in
personal online banking, where they are known
as Transaction Authentication Numbers (TANs). As most
home users only perform a small number of transactions
each week, the single use issue has not led to intolerable
customer dissatisfaction in this case.
 Time-synchronized one-time passwords are similar in some
ways to single-use passwords, but the value to be entered
is displayed on a small (generally pocketable) item and
changes every minute or so.
 PassWindow one-time passwords are used as single-use
passwords, but the dynamic characters to be entered are
visible only when a user superimposes a unique printed
visual key over a server generated challenge image shown
on the user's screen.
 Access controls based on public key cryptography e.g. ssh.
The necessary keys are usually too large to memorize (but
see proposal Passmaze)[69] and must be stored on a local
computer, security token or portable memory device, such
as a USB flash drive or even floppy disk. The private key
 may be stored on a cloud service provider, and activated
by the use of a password or two factor authentication.
 Biometric methods promise authentication based on
unalterable personal characteristics, but currently (2008)
have high error rates and require additional hardware to
scan, for example, fingerprints, irises, etc. They have
proven easy to spoof in some famous incidents testing
commercially available systems, for example, the gummie
fingerprint spoof demonstration,[70] and, because these
characteristics are unalterable, they cannot be changed if
compromised; this is a highly important consideration in
access control as a compromised access token is
necessarily insecure.
 Single sign-on technology is claimed to eliminate the need
for having multiple passwords. Such schemes do not
relieve user and administrators from choosing reasonable
single passwords, nor system designers or administrators
from ensuring that private access control information
passed among systems enabling single sign-on is secure
against attack. As yet, no satisfactory standard has been
developed.
 Envaulting technology is a password-free way to secure
data on removable storage devices such as USB flash
drives. Instead of user passwords, access control is based
on the user's access to a network resource.
 Non-text-based passwords, such as graphical
passwords or mouse-movement based passwords.
[71]
 Graphical passwords are an alternative means
of authentication for log-in intended to be used in place of
conventional password; they
use images, graphics or colours instead
of letters, digits or special characters. One system requires
users to select a series of faces as a password, utilizing
the human brain's ability to recall faces easily.[72] In some
implementations the user is required to pick from a series
of images in the correct sequence in order to gain access.
[73]
 Another graphical password solution creates a one-time
password using a randomly generated grid of images. Each
time the user is required to authenticate, they look for the
images that fit their pre-chosen categories and enter the
randomly generated alphanumeric character that appears
in the image to form the one-time password. [74][75] So far,
graphical passwords are promising, but are not widely
used. Studies on this subject have been made to determine
its usability in the real world. While some believe that
graphical passwords would be harder to crack, others
 suggest that people will be just as likely to pick common
images or sequences as they are to pick common
passwords.[citation needed]
 2D Key (2-Dimensional Key)[76] is a 2D matrix-like key input
method having the key styles of multiline passphrase,
crossword, ASCII/Unicode art, with optional textual
semantic noises, to create big password/key beyond 128
bits to realize the MePKC (Memorizable Public-Key
Cryptography)[77] using fully memorizable private key upon
the current private key management technologies like
encrypted private key, split private key, and roaming private
key.
 Cognitive passwords use question and answer
cue/response pairs to verify identity.

"The Password is dead"[edit]

That "the password is dead" is a recurring idea in computer security. It often
accompanies arguments that the replacement of passwords by a more secure means of
authentication is both necessary and imminent. This claim has been made by numerous
people at least since 2004. Notably, Bill Gates, speaking at the 2004 RSA
Conference predicted the demise of passwords saying "they just don't meet the
challenge for anything you really want to secure." [68][78] In 2011, IBM predicted that, within
five years, "You will never need a password again." [79] Matt Honan, a journalist at Wired,
who was the victim of a hacking incident, in 2012 wrote "The age of the password has
come to an end."[80] Heather Adkins, manager of Information Security at Google, in 2013
said that "passwords are done at Google." [81] Eric Grosse, VP of security engineering at
Google, states that "passwords and simple bearer tokens, such as cookies, are no
longer sufficient to keep users safe."[82] Christopher Mims, writing in the Wall Street
Journal said the password "is finally dying" and predicted their replacement by device-
based authentication.[83] Avivah Litan of Gartner said in 2014 "Passwords were dead a
few years ago. Now they are more than dead." [84] The reasons given often include
reference to the usability as well as security problems of passwords.
The claim that "the password is dead" is often used by advocates of alternatives to
passwords, such as biometrics, two-factor authentication or single sign-on. Many
initiatives have been launched with the explicit goal of eliminating passwords. These
include Microsoft's Cardspace, the Higgins project, the Liberty Alliance, NSTIC,
the FIDO Alliance and various Identity 2.0 proposals. Jeremy Grant, head of NSTIC
initiative (the US Dept. of Commerce National Strategy for Trusted Identities in
Cyberspace), declared "Passwords are a disaster from a security perspective, we want
to shoot them dead."[85] The FIDO Alliance promises a "passwordless experience" in its
2015 specification document.[86]
In spite of these predictions and efforts to replace them passwords still appear as the
dominant form of authentication on the web. In "The Persistence of Passwords,"
Cormac Herley and Paul van Oorschot suggest that every effort should be made to end
the "spectacularly incorrect assumption" that passwords are dead. [87] They argue that "no
other single technology matches their combination of cost, immediacy and convenience"
and that "passwords are themselves the best fit for many of the scenarios in which they
are currently used."
Following the work of Herley and van Oorschot, Bonneau et al. systematically compared
web passwords to 35 competing authentication schemes in terms of their usability,
deployability, and security.[88][89] (The technical report is an extended version of the peer-
reviewed paper by the same name.) Their analysis shows that most schemes do better
than passwords on security, some schemes do better and some worse with respect to
usability, while every scheme does worse than passwords on deployability. The authors
conclude with the following observation: “Marginal gains are often not sufficient to reach
the activation energy necessary to overcome significant transition costs, which may
provide the best explanation of why we are likely to live considerably longer before
seeing the funeral procession for passwords arrive at the cemetery.”

See also[edit]
 Access code (disambiguation)
 Authentication
 CAPTCHA
 Cognitive science
 Diceware
 Kerberos (protocol)
 Keyfile
 Passphrase
 Password cracking
 Password fatigue
 Password length parameter
 Password manager
 Password notification e-mail
 Password policy
 Password psychology
 Password strength
 Password synchronization
 Password-authenticated key agreement
 Pre-shared key
 Random password generator
 Rainbow table
 Self-service password reset
 Usability of web authentication systems

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External links[edit]
 Graphical Passwords: A Survey
 Large list of commonly used passwords
 Large collection of statistics about passwords
 Research Papers on Password-based Cryptography
 The international passwords conference
 Procedural Advice for Organisations and
Administrators (PDF)
 Centre for Security, Communications and Network
Research, University of Plymouth (PDF)
  2017 draft update to NIST password standards  for the U.S.
federal government
 Memorable and secure password generator
Categories: 
 Password authentication
 Identity documents
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