Provided by: dacs_1.4.28b-3ubuntu2_amd64 bug


       dacstoken - administer hash-based one-time passwords


       dacstoken [dacsoptions[1]] [-all] [-base num] [-counter num] [-digits num]
                 [-disable | -enable] [-hotp-window num] [-inkeys item_type]
                 [[-key keyval] | [-key-file filename] | [-key-prompt]] [-mode otp-mode]
                 [-outkeys item_type]
                 [[-pin pinval] | [-pin-file filename] | [-pin-prompt]] [-pin-constraints str]
                 [-rnd] [-seed str] [-serial str] [-totp-delta num] [-totp-drift nwindows]
                 [-totp-hash alg]
                 [-totp-timestep secs] [-vfs vfs_uri] [op-spec] [username]


       This program is part of the DACS suite.

       The dacstoken utility administers DACS accounts associated with one-time password (OTP)
       generating devices (tokens) or software-based clients. Using command line options, it also
       computes OTP values; token account parameters can be overridden, but accounts are not even

       Strong, two-factor authentication can be provided when dacs_authenticate[2] is configured
       to use the local_token_authenticate[3] authentication module or when dacstoken is used as
       a standalone program to validate passwords. Both the HMAC-based one-time password mode
       (HOTP), based on an event counter and specified by RFC 4226[4], and the time-based
       one-time password mode (TOTP), as specified by the latest IETF Internet-Draft[5] proposal,
       are supported.  Additional operational modes[6] called OCRA (OATH Challenge-Response
       Algorithms), described in an IETF Internet-Draft, are not yet fully supported.

           This version of dacstoken incorporates many changes that are not backward compatible
           with release 1.4.24a and earlier. Some command line flags function differently, and
           the format of the account file has changed. If you have used this command in earlier
           releases, please make a backup copy of your token account file and review this manual
           page carefully before proceeding (note the -convert flag[7] in particular).

           No vendor-supplied software is required by dacstoken to supply its functionality. The
           devices currently supported do not need any registration or configuration interaction
           with vendors and dacstoken does not interact with vendors' servers or use any
           proprietary software. Vendor-supplied software may be required to perform
           initialization or configuration for other token devices, however, and dacstoken does
           not provide such support for them.

       Each token device generally corresponds to exactly one account that is managed by
       dacstoken, although some vendors produce tokens that can support multiple accounts.

       To summarize, this utility:

       ·   creates and administers DACS accounts associated with counter-based and time-based
           one-time passwords

       ·   provides validation and testing functionality

       ·   provides a command line authentication capability

           Only the DACS administrator should be able to successfully run this program from the
           command line. Because DACS keys and configuration files, including the file used to
           store accounts, must be restricted to the administrator, this will normally be the
           case, but a careful administrator will set file permissions to deny access to all
           other users.

           The dacs_token(8)[8] web service provides users with limited self-service
           functionality to set or reset their account PIN and synchronize their token. It also
           has a demonstration mode to simplify testing and evaluation.

   PINs (Account Passwords)
       A dacstoken account can optionally have a PIN (i.e., a password) associated with it. To
       authenticate against such an account, a user must provide the one-time password produced
       by the token and the PIN. The TOKEN_REQUIRES_PIN[9] configuration directive determines
       whether a PIN must be provided when creating or importing an account; it does not apply in
       conjunction with the -delpin flag, since only an administrator should be able to perform
       that function.

       A hash of the PIN is stored in the account record rather than the PIN itself. The same
       method used by dacspasswd(1)[10] and dacs_passwd(8)[11] is applied, and depends on the
       PASSWORD_DIGEST[12] and PASSWORD_SALT_PREFIX[13] directives in effect. If
       PASSWORD_DIGEST[12] is configured, that algorithm is used, otherwise a compile-time
       default (SHA1) is used. If a user forgets the PIN, the old one cannot be recovered so it
       must either be deleted or a new one must be set.

       Some token devices have a PIN capability built into them. The user must enter a PIN into
       the device before the device will emit a one-time password. This "device PIN" is
       completely distinct from the account PIN that is managed by dacstoken, and this manual is
       only concerned with the dacstoken PIN. The device PIN should always be used when possible;
       the dacstoken PIN is strongly recommended and is required for two-factor authentication
       (unless an additional authentication factor is applied in some other way).

       Since only the administrator is allowed to run this command, no restrictions are imposed
       on the length or quality of the PINs that the administrator supplies; a warning message
       will be emitted, however, if the password is considered to be weak as determined by the
       PASSWORD_CONSTRAINTS[14] directive.

   One-Time Passwords
       Both kinds of one-time password device compute a password value by employing a secure
       keyed hash algorithm (RFC 2104[15], FIPS 198[16]). In the counter-based method, the device
       and server share a secret key and a counter value which are hashed to yield a numerical
       value displayed in a certain radix with a certain number of digits. Successful
       authentication requires the device and server to compute matching passwords. Each time the
       device produces a password, it increments its counter. When the server receives a matching
       password, it increments its counter. Because it is possible for the two counters to become
       unsynchronized, the server's matching algorithm will typically allow a client's password
       to fall within a "window" of counter values. The time-based method is similar, the main
       difference being that the current Unix time (as returned by time(3)[17], for instance) is
       used to establish a "time-step window" that serves as a counter value in the computation
       of the secure hash. Because the real-time clocks on the device and server may not be
       sufficiently synchronized, the server's matching algorithm must also allow a client's
       password to fall within some number of time-step windows for these devices.

           A token may be assigned a permanent secret key (sometimes called an OTP seed) by its
           manufacturer or the key may be programmable. This secret key is used by the token's
           password generation procedure and it is critical that it be kept private. If the token
           is not programmable, the key is obtained from the vendor (for a HOTP token, typically
           by providing the device's serial number and any three consecutive passwords). A record
           of each mapping from serial number to secret key should be kept in a secure location.

           If the secret key is programmable, as it is likely to be with a software client, it is
           required to be at least 128 bits in length; a minimum of 160 bits is recommended. The
           key is represented by a 16 (or more) character long hexadecimal string. The key should
           be obtained from a cryptographic-quality source of random bits. Some clients may be
           capable of generating a suitable key, but you may use dacsexpr(1)[18]:

               % dacsexpr -e "random(string, 20)"

           Tokens can be used for authentication purposes other than computer sign on. For
           example, by providing an account number, PIN, and token value, customers can quickly
           be authenticated over the phone, reducing or eliminating the need for expensive and
           time-consuming security questions.

       One-time password devices and applications have the following operational parameters.
       These parameters determine the password sequence that is generated. Some operational
       parameters may be fixed (by the relevant standard or due to the implementation), while
       others may be partially or completely configurable by the user. Please refer to the
       references and manufacturers' documentation for details.

           The radix in which passwords are displayed.

           For HOTP mode only, the current counter value.

           The number of digits in each one-time password.

           The secret key (OTP seed).

       serial number
           A unique identifier or name for the device.

       time step size
           For TOTP mode only, the width of each time interval, in seconds. The same password
           will be generated within a given interval; i.e., this is the "lifetime" or validity
           period of each TOTP password.

       In addition to these parameters, dacstoken employs several per-account (i.e., per-device)

           When validating a HOTP password, the maximum number of passwords to consider after the
           expected password.

           For TOTP mode only, the number of seconds by which to adjust the server's clock
           forward or backward to better synchronize it with the device. This is used to
           compensate for tokens or client software whose clocks are not well synchronized with
           the server's.

           For TOTP mode only, but analogous to the accept-window, the maximum number of
           intervals (each of the time step size) to search forward and backward when validating
           against a given password.

           For HOTP mode only, the number of consecutive one-time passwords required to
           synchronize the account with the device.

           The name of the DACS account bound to the device.

       Authentication based on one-time password devices has the following advantages:

       ·   Each time a user authenticates, a different password will be generated (with high
           probability); users cannot therefore jot down "the password" because the password is
           always changing; users cannot forget their password;

       ·   Once used, a HOTP mode password is immediately "consumed" and is unlikely to be used
           again for a long time; with suitable configuration parameters, a TOTP mode password
           automatically "expires" within a relatively short time interval and is unlikely to be
           used again for a long time;

       ·   If no correction for clock drift is required, a TOTP mode account can have read-only

       ·   Because the password is unlikely to be an easily-guessed number or string, it should
           be stronger than most user-selected passwords;

       ·   A HOTP token can be the basis of a mutual ("bidirectional") authentication method; the
           server shows the user his token's next password to confirm its identity (with both
           parties advancing their counters), then the client shows the server the next password
           to confirm his identity;

       ·   Should a key sniffer be installed on the user's computer, a sniffed password does not
           do an attacker any good unless a man-in-the-middle attack[19] is possible; given N
           consecutive passwords it is still very difficult to compute password N + 1 without
           knowing the secret key;

       ·   It is more difficult for users to share an account (although users might sometimes
           view this as an inconvenience);

       ·   If a dacstoken PIN is assigned to an account and an attacker obtains the account's
           token, it is still difficult for the attacker to authenticate without knowing the PIN;

       ·   A quick and immediately effective way to disable an account is by simply seizing a
           hardware token (e.g., if an employee is fired), although an account can be disabled by
           this program or using the revocation list[20];

       ·   In the case of a software client that runs on a mobile device, such as a phone or PDA,
           users are already carrying the device with them; free clients are available, so there
           may be no additional cost (note that mobile devices may not offer the same
           tamper-resistance, durability, key secrecy, clock accuracy, etc. of a hardware token).

       One-time password devices have the following potential disadvantages:

       ·   There is a one-time expense for a hardware token (depending on the purchase volume,
           you can expect to pay $10-$100 USD each), and there is the possibility of having to
           replace a lost or broken token, or a token's battery (some units have a
           non-replaceable battery, making them disposable after a few years);

       ·   Initial configuration is somewhat more difficult than with other authentication
           methods, and users unfamiliar with the devices will have to be instructed on their

       ·   Although they are typically quite small (e.g., 5cm x 2cm x 1cm) and can be attached to
           a keychain or lanyard, or kept in a wallet, users may wince at having to carry a token
           around with them;

       ·   Users can forget to have their token with them or lose the token;

       ·   A mobile device (with a software client) is probably a likely target for theft, more
           so than a hardware token (hence the extra importance of a PIN for this device);

       ·   Unlike a hardware token where the key is burned into inaccessible, tamper-proof
           memory, the key configured into a software client is likely to be readable by its
           owner, making sharing of the account possible;

       ·   Entering a 40 character or longer seed value into a mobile device can be frustrating
           and prone to error;

       ·   Once a TOTP device generates a password, a new password cannot be generated until the
           next time-step window, requiring the user to wait 30 (or possibly 60) seconds (e.g.,
           if an entry error is made);

       ·   Some devices are difficult to read in low-light conditions; presbyopic users and those
           with impaired vision may have difficulty reading the display.

       The accounts managed by dacstoken are completely separate from the accounts used by
       local_passwd_authenticate[21] or any other DACS authentication module.

       Accounts for HOTP and TOTP devices may either be combined or kept separate. If the virtual
       filestore item type auth_hotp_token is defined, it is only used for accounts associated
       with HOTP tokens. Similarly, if the virtual filestore item type auth_totp_token is
       defined, it is only used for accounts associated with TOTP tokens. If either item type is
       not defined, accounts are accessed through DACS's virtual filestore using item type
       auth_token. It is assumed that file permissions on the account databases are such that all
       access is limited to the administrator and local_token_authenticate.

       If accounts for the two device types are combined, because each username for an
       authentication method must be unique, if an individual has both types of token they must
       be assigned different usernames. So, for example, if Auggie has one HOTP token and one
       TOTP token, the former might correspond to the username auggie-hotp and the latter to
       auggie-totp; the sign-on form might include a device-mode input which would allow Auggie
       to simply type "auggie" in the username field and JavaScript to automatically append the
       appropriate suffix based on the select device mode. An obvious disadvantage of this
       configuration is that it results in two different DACS identities for the same individual;
       this would have to be remembered if an access control rule needed to identify Auggie
       explicitly. If both tokens should map to the same DACS identity, the Auth clause could
       strip the suffix off after successful authentication, but the administrator would then
       need to beware of the case of two different Auggies, each using a different device type.

       Configuring both the auth_hotp_token and auth_totp_token item types (or just one of them
       and auth_token) keeps the accounts separate and allows the same username to be used for
       both types of devices. Auggie could therefore have an account record with the same
       username for both device types. This approach requires the device mode to be specified
       when an operation is requested so that the correct item type can be used; this means that
       users must know which type of device they are using (perhaps by afixing a label to it).
       Refer to important details regarding DACS identities[22].

       The -vfs is used to configure or reconfigure the auth_token item type.

       Only keys that meet the minimum key length requirement (16 bytes) may be stored with
       account information (e.g., with -set or -import). In other contexts, the requirement is
       not enforced.

       The secret key is encrypted by dacstoken when it is written to the account file. The
       virtual filestore item type auth_token_keys identifies the encryption keys for dacstoken
       to use; the -inkeys and -outkeys flags specify alternatives (see dacskey(1)[23]). If the
       encryption keys are lost, the secret keys are practically unrecoverable.

           If an attacker discovers a secret key, generating usable passwords without possessing
           the token will not be difficult. For at least some hardware tokens, the key is burned
           in to the device and cannot be changed; in this case, if the key is leaked the device
           should be destroyed. If a token is lost, the corresponding account should be disabled.
           In the event an attacker finds a lost token or discovers a secret key, having a strong
           PIN associated with the account will make it difficult for the attacker to gain

           ·   This authentication method has been tested against the following OTP products:

               ·   Authenex A-Key 3600[24] one-time password (HOTP) hardware token;

               ·   Feitian Technologies[25] OTP C100 and OTP C200 one-time password hardware
                   tokens, provided by HyperSecu Information Systems[26]; and

               ·   OATH Token[27] software application by Archie Cobbs, which implements both
                   HOTP and TOTP on the iPod Touch, iPhone, and iPad[28].

               ·   Feitian Technologies iOATH Lite[29] HOTP software application for the iPod
                   Touch, iPhone, and iPad.

               Other manufacturers interested in having their products supported by DACS are
               welcome to contact Dss.

           ·   Photo[30]: Feitian OTP C200, iPod Touch with the OATH Token app, Authenex A-Key
               3600 (clockwise from top left)

           ·   Although this implementation should work with similar, conformant products, only
               these products are officially supported by DACS.

           ·   Hardware tokens can be purchased directly from the vendors.

           ·   Any problems with using tokens to authenticate through DACS are not the
               responsibility of the token vendor.

   Importing and Exporting OTP Accounts
       Descriptions of accounts and their tokens can be loaded or dumped (refer to the -import
       and -export flags). This simplifies bulk provisioning, backup, and portability. The
       account information is written in a simple, application-specific (almost) XML format.

       The format understood by dacstoken consists of a root element ("otp_tokens"), followed by
       zero or more "otp_token" elements, one per line, each with required and optional
       attributes (described below). The XML declaration must be omitted. Leading whitespace and
       blank lines are ignored, as are single line XML comments. Additionally, lines having a "#"
       as the first non-whitespace character are ignored. Optional attributes that are not
       present are assigned default values. The default digest algorithm is SHA1. Short attribute
       names are used to save space. Unrecognized attributes, and attributes irrelevant to the
       device mode, are ignored. Single or double quote characters (or both) within XML attribute
       values must be replaced by the corresponding entity reference ("'" and """,
       respectively), as must the "<" (less than) and "&" (ampersand) characters. A ">" (greater
       than) character may optionally be replaced by a "&gt;" sequence, but no other entity
       references are recognized.

       Recognized attributes are:

       ·   b:
             -- radix for OTP value
             10 (default),
             16, or 32]

       ·   c:
             -- current counter value for HOTP, in hex if preceded
             by "0x" (or "0X"), decimal otherwise
             default is 0]

       ·   d:
             OTP device mode
             -- "c" (for HOTP)
             or "t" (for TOTP)

       ·   dn:
             -- one of the Secure Hash Algorithms
             SHA1 (default),
             SHA224, SHA256,
             SHA384, SHA512]

       ·   dr:
             -- clock adjustment, in seconds, for TOTP

       ·   ek:
             -- encrypted secret key, base-64 encoded
             OTP account records only]

       ·   en:
             -- 1 for enabled,
             0 for disabled

       ·   k:
             -- unencrypted secret key

       ·   lu:
             -- Unix time of last record update
             [Optional: default is current time]

       ·   nd:
             -- number of digits for OTP value
             default is 6 for HOTP,
             8 for TOTP]

       ·   p:
             -- plaintext PIN value for the account
             unless ph is present,
             for import only]

       ·   ph:
             -- hashed PIN value for the account
             generated by dacstoken
             for export and OTP account files only]

       ·   s:
             -- unique identifier string for the device

       ·   ts:
             -- time-step value, in seconds, for TOTP
             default is 30]

       ·   u:
             -- a valid DACS username associated with this account

       The following example describes two accounts that might be created using the -import flag:

           <!-- Staff OTP tokens for DACS authentication -->
           <otp_token u="ietf" d="t" en="1" s="totp-ietf &quot;draft&quot;" k="3132333435363738393031323334353637383930" dn="SHA1" ts="30"/>
           <otp_token u="ipod-c" d="c" en="1" s="ipodc-9C841SD4203" k="19c0a3519a89b4a8034c5b9306db" dn="SHA1" c="0" nd="6" b="10"/>

           Because imported records include the unencrypted secret keys for the OTP devices, the
           exported file should be kept encrypted (e.g., using openssl) or at least have
           appropriate file permissions.

           A standard format for OTP device provisioning is being developed. This format may be
           understood by a future version of dacstoken, or a conversion utility may be written.
           The standard format is likely to be considerably more complex than the DACS format.


       In addition to the standard dacsoptions[1], a lengthy list of command line flags are
       recognized. When a username is given, default values associated with that account are
       used, otherwise recommended or implementation-specific defaults are used. These default
       values can usually be overridden on the command line. Some flags are only allowed with a
       particular token mode (e.g., -counter, -totp-show) and their appearance implies that mode,
       making the -mode flag unnecessary; other flags are mode independent (e.g., -delete,
       -enable). It is an error to use a mutually incompatible flag combination. Flags that are
       meaningless with the selected operation are ignored, although they still imply a mode.
       Hexadecimal values are case insensitive. If a counter value is required but unspecified
       (e.g., when creating an account), an initial counter value of zero is used.

       The op-spec specifies the operation to be performed, together with zero or more modifier
       flags. If op-spec is missing, the -list operation is performed. An op-spec is one of the

       -auth otp-value
           This flag is like -validate[31], except:

           ·   a username is required, from which all parameters are obtained (such as the key);

           ·   if the account has a PIN, it must be provided;

           ·   if the account is for a HOTP token, the counter will be updated if authentication
               is successful.

           An exit status of zero indicates successful authentication, while any other value
           means authentication failed.

       -convert filename
           Load an older format (prior to release 1.4.25) token account file from filename ("-"
           means to read from stdin), convert it to the newer format, and write it to stdout (as
           by -export). This flag is deprecated and this capability will be removed in a future
           release of DACS.

           Create an account for username, which must not already exist. In other respects it
           works like -set[32]. When creating a new account, -serial is required and -key is
           implied. If no -enable flag is provided when creating an account, -disable is implied.
           If no -counter flag is provided, a default of zero is used. If one of the PIN flags is
           present, the given PIN will be assigned to the account, otherwise the account will not
           have a PIN (or the existing PIN will not be changed).

           Display the current moving factor (i.e., the counter value for HOTP or the interval
           value for TOTP) and expected OTP for username. For HOTP, the counter is advanced. All
           parameters are taken from the account.

           Delete the account for username. The device's secret key and other operational
           parameters will be lost.

           Delete the PIN, if present, on the account for username, leaving the account without a

           Write information about all accounts, or only one account if username is given, to
           stdout. If a mode is selected, however, only accounts having that mode will be
           written. This information may be reloaded using -import or -import-replace. The output
           should be stored in an encrypted form, or at the very least have its file permissions
           set appropriately. For example:

               % dacstoken -uj EXAMPLE -export | openssl enc -aes-256-cbc > dacstoken-exported.enc

           Later, you might do something like:

               % openssl enc -d -aes-256-cbc < dacstoken-exported.enc | dacstoken -uj EXAMPLE -import -

           Display a help message and exit.

       -hotp-show num
           Display num consecutive HOTP passwords from a given counter value and key. The
           -counter flag can be used to specify an initial counter value. The key can be
           specified using -key, -key-file, or -key-prompt. If a username is provided, the
           initial counter value and key are obtained from the user's HOTP account, unless either
           value is overridden on the command line; the account's stored counter value is not
           modified. This is mainly intended for debugging purposes.

       -import filename
       -import-replace filename
           Load account and token information from filename; if filename is "-", stdin is read.
           If a mode is selected, only accounts having that mode will be read. With -import it is
           an error if an imported account already exists, and processing stops; -import-replace
           will replace an existing account with imported data.

           If username is provided, display information about the corresponding account; if the
           -serial flag is given, display information about the account with the specified serial
           number; otherwise list all accounts. If the -mode flag is given in any of these cases,
           however, list only those accounts that have the operational mode specified. If this
           flag is repeated, or with the -long flag, more detail is displayed: device type,
           account status, device serial number, counter value (for HOTP), clock drift value (for
           TOTP), whether or not the account has a PIN (indicated by a "+" or "-" symbol), and
           the time and date of the account's last modification.

       -rename new-username
           Rename the existing account for username to be new-username, and modify the new
           account using command line arguments (as with -set[32]). As this requires two steps
           that are not done atomically, if an error occurs it is possible for the new account to
           be created and the old account to still exist.

           The -set flag is used to modify the existing account for username based on one or more
           modifier arguments (-base, -counter, -digits, -disable or -enable, -key (or -key-file
           or -key-prompt), -pin (or -pin-file or -pin-prompt), or -serial). The mode can also be
           changed by specifying -mode, but mode-specific parameters associated with the account
           will be lost (e.g., the current counter value will be deleted if a HOTP account is
           changed to a TOTP account) and general parameters (such as the serial number) will be
           retained unless overridden on the command line.

       -sync password-list
           In HOTP mode, this attempts to synchronize the server with the token for username. The
           password-list is a comma-separated list of three successive passwords produced by the
           user's token (this "auto-synchronize" function is also available through
           local_token_authenticate[3]). The given sequence must match the computed sequence
           exactly, given the operational parameters in effect; e.g., leading zeroes are
           significant, as is the display radix and number of OTP digits in effect. If
           synchronization is successful, the user should be able to authenticate using the next
           password produced by the device. An exhaustive search algorithm using increasing
           counter values is employed, with a compile-time limit on the maximum number of
           computations. The search begins at the server's currently stored counter value, unless
           one is provided using -counter. If unsuccessful, this operation could take a long time
           before it terminates; the user must contact an administrator for assistance.

           In TOTP mode, attempt to determine how closely synchronized the system clock is with
           the token's clock and display the result. This information can be used to update the
           user's token record to compensate for poorly synchronized clocks, or to adjust
           validation parameters. The token's key and the name of the digest algorithm are
           obtained for the token record belonging to username, if it is given; otherwise the key
           is prompted for and the digest algorithm to use is either obtained from the command
           line or the default. Only the first password in password-list is used. The
           -totp-timestep, -digits, and -totp-base options are effective during this operation.

           Perform some self-tests, then exit. A non-zero exit status means an error occurred.

       -totp-show num
           Display a sequence of TOTP passwords using the parameters currently in effect:
           interval size (-totp-timestep), number of digits (-digits), and base (-base). The
           account's stored parameters are not modified. This is mainly intended for debugging

           If a username is provided (it must be associated with a TOTP device), the key and
           other stored parameters from the account are used unless overridden by command line
           flags. The sequence of passwords for num intervals before and after the current time,
           together with the password for the current time are printed.

           If no username is given, the program prompts for the key (which is echoed) and uses
           command line flags or default values for parameters. It then emits the TOTP password
           for the current time each time Return/Enter is pressed. Typing EOF causes immediate

       -validate otp-value
           If otp-value is the next expected one-time password, return an exit status of zero to
           indicate success; any other value indicates failure. If username is given, parameters
           for validation, including the key, are obtained from that account unless overridden on
           the command line. The server's state is not changed; e.g., a HOTP counter is not
           advanced. If no username is given, the -mode flag must be used and the parameters
           required for that mode must be given, including a key. For HOTP mode, a counter value
           must be provided. For TOTP mode, command line parameters are effective during this
           validation.  dacstoken will test whether otp-value validates against the parameters in

       The following modifier flags are understood:

           With -set and no username, apply the changes to all accounts. This can be used to
           enable or disable all accounts, for example. The -inkeys and -outkeys flags are
           honoured. If an error occurs processing stops immediately, in which case only some
           accounts may have been modified.

       -base num
           Use num as the base (radix) when displaying an OTP. The value of num is restricted to
           10 (the default), 16, or 32.

       -counter num
           This is the 8-byte HOTP counter value to set, expressed as a hex value if preceded by
           by "0x" (or "0X"), decimal otherwise. Leading zeroes may be elided. This implies HOTP
           mode. For token devices, it should not be possible to reset a counter (modulo counter
           overflow) because that will result in the password sequence being repeated, assuming
           that the key is not changed; software implementations might not have this restriction,
           however, so beware of the security implications.

       -digits num
           Use num digits when displaying an OTP. The value of num is restricted to 6, 7, 8 (the
           default), or 9 with base 10. It is restricted to 6 with base 32 and is ignored with
           base 16 (hex output).

           Disable the account for username. The local_token_authenticate module, and -auth and
           -validate flags, will not allow the user to authenticate until the account has been
           enabled, although other operations may still be performed on the account. If -enable
           is subsequently used, the account will become usable for authentication and is
           restored to its state at the time it was disabled. It is not an error to disable an
           already disabled account.

           Enable the account for username. The local_token_authenticate module will allow the
           user to authenticate. It is not an error to enable an already enabled account.

       -hotp-window num
           If the expected HOTP password does not match the given password, try to match up to
           num passwords after the expected password in the sequence. A value of zero for num
           disables this search.

       -inkeys item_type
           For decrypting secret keys, use the store identified by item_type, presumably
           configured in dacs.conf.

       -key keyval
           Use keyval as the secret key, expressed as a hex digit string.

               Supplying a key on the command line is not secure because it may be visible to
               other processes.

       -key-file filename
           Read the secret key, expressed as a hex digit string, from filename. If filename is
           "-", the key is read from stdin.

           Prompt for the secret key, expressed as a hex digit string. The input is not echoed.

       -mode otp-mode
           This specifies (case insensitively) the type of token (the OTP device mode) for use
           with -set, -create, and validation and synchronization operations. The otp-mode may be
           either counter or hotp for counter mode, or time or totp for time-based mode. This
           flag is required when creating a new account.

       -outkeys item_type
           For encrypting secret keys, use the store identified by item_type, presumably defined
           in dacs.conf.

       -pin pinval
           Use pinval as the secret PIN for the account.

               Supplying a PIN on the command line is not secure because it may be visible to
               other processes.

       -pin-constraints str
           Instead of using PASSWORD_CONSTRAINTS[14], use str (having the same syntax and
           semantics) to describe the requirements for a PIN.

               Requirements for a PIN apply to PINs obtained via a command line flag and to those
               obtained through importing (using the "p" attribute). Requirements are not
               "retroactive", however, so changing the requirements does not affect the PINs of
               existing accounts or importing accounts that were previously exported (having a
               "ph" attribute).

       -pin-file filename
           Read the secret PIN from filename. If filename is "-", the PIN is read from stdin.

           Prompt for the secret PIN. The input is not echoed.

           Reserved for future use.

       -seed str
           Reserved for future use.

       -serial str
           The serial number, str, is a (purportedly) unique identifier assigned to the token.
           This option is used with the -set, -create, and -list flags. A serial number
           identifies a specific OTP device and need not be kept secret. The uniqueness property
           is enforced within an item type storage unit; that is, serial numbers of all HOTP
           devices must be unique, serial numbers of all TOTP devices must be unique, and if
           accounts for the two device types are combined, all device serial numbers must be
           unique. Any printable string is accepted. If a software client is generating
           passwords, you may use the device's serial number, or choose any suitably descriptive
           string not already assigned to a device.

               A jurisdiction that allows (or may eventually allow) both hardware tokens and
               software-generating client applications should consider adopting a formalized
               naming scheme for its tokens. For example, the administrator might append "-hw" to
               the vendor's serial number to form the dacstoken serial number. For software
               tokens, the administrator might create a dacstoken serial number by appending
               "-sw" to the vendor's serial number for the device.

       -totp-delta num
           Adjust the base time by num intervals (each of the step size number of seconds) when
           computing a TOTP. The num may be negative, zero, or positive. This is used to correct
           for inadequately synchronized clocks.

       -totp-drift nwindows
           For TOTP, use a window size of nwindows (in terms of the interval size) for
           validation. If nwindows is 0, the computed TOTP value must match the given one
           exactly. If nwindows is 1, for example, dacstoken will try to match the given TOTP
           value in the previous, current, and next intervals. This allows the clocks in the
           system running dacstoken (or local_token_authenticate) and token producing device to
           be less well synchronized.

               Although it compensates for poorly synchronized clocks, increasing the value of
               nwindows weakens the system by extending the lifetime of a one-time password.

       -totp-hash alg
           Use alg as the digest algorithm with TOTP. The value of alg is restricted to (case
           insensitively) SHA1 (the default), SHA256, or SHA512.

       -totp-timestep secs
           Use secs as the interval size when computing a TOTP. It must be greater than zero. The
           default is 30 seconds.

               Although it compensates for poorly synchronized clocks, increasing the value of
               secs weakens the system by extending the lifetime of a one-time password.

       -vfs vfs_uri
           Use vfs_uri to override the VFS[33] configuration directive in effect. This can be
           used to configure or reconfigure auth_token, auth_hotp_token, or auth_totp_token to
           specify the storage method for the accounts being acted upon.

       Apart from error messages, which are printed to the standard error, all output goes to the
       standard output.

       Ordinarily, a dacsoption will be specified to select the jurisdiction on behalf of which
       accounts are being managed.


       These examples assume that the jurisdiction name to use is EXAMPLE and its federation
       domain is

       To use this authentication method, a DACS administrator might perform the following steps
       for each OTP device assigned to a user:

        1. Obtain a supported token, review how it is used for authentication, and select values
           for the various parameters. Obtain the secret key for the device from the vendor; for
           a programmable device, select a suitable random key and program it into the device.
           The current counter values might also be obtained from the vendor, although it is
           likely to initialized to zero; for a programmable device, set the counter value to
           zero. Decide whether a PIN will be required (see TOKEN_REQUIRES_PIN[9]). If a software
           client is being used, install the software on the user's device (or have the user do
           so), and configure the software.

        2. Decide where the account information will be stored and, if necessary, add a suitable
           VFS[33] directive to dacs.conf. The default (found in site.conf) maintains the account
           information in a file named auth_tokens within each jurisdiction's default private

               VFS "[auth_token]dacs-kwv-fs:${Conf::FEDERATIONS_ROOT}/\

        3. Generate keys to encrypt the account information (see Tokens and secret keys[34]) and
           decide where they will be stored; for example (your user ID, group ID, path,
           jurisdiction name, and federation domain may vary):

               % cd /usr/local/dacs/federations_root/
               % dacskey -uj EXAMPLE -q auth_token_keys
               % chgrp www auth_token_keys
               % chmod 0640 auth_token_keys

           If necessary, add a suitable VFS[33] directive to dacs.conf; the default, which is
           used above, maintains the account information in a file named auth_token_keys within
           each jurisdiction's default private area:

               VFS "[auth_token_keys]dacs-fs:${Conf::FEDERATIONS_ROOT}/\

        4. If you need users to sign on through dacs_authenticate(8)[2], you must configure a
           suitable Auth clause in dacs.conf, for example:

               <Auth id="token">
                 URL "token"
                 STYLE "pass"
                 CONTROL "sufficient"

        5. There are several ways that an administrator might proceed, depending on how much of
           the effort can be done by users (e.g., whether they can be trusted, their technical
           ability), how many users there are (a few, or thousands), and the level of security

            1. prepare a file containing an XML record[35] for each account to be created; if
               PINs are to be used, assign a random PIN to each account;

            2. use the -import[36] flag to create the accounts;

            3. give the token device, username, and (if necessary) initial PIN to the user
               (perhaps verifying identity), providing any necessary demonstration and

            4. have the user set or reset the PIN for the account, and ask the user to sign on
               using the token to confirm correct operation.

       To create a disabled account for user bobo for a HOTP device:

           % dacstoken -uj EXAMPLE -mode hotp -serial 37000752 -key-file bobo.key -create bobo

       The secret key for the account (which must not already exist) is read from the file
       bobo.key. New accounts are disabled by default; use -enable to create an enabled account.

       Once an account has been created, it can be synchronized with the token. To synchronize
       the HOTP token for user bobo:

           % dacstoken -uj EXAMPLE -sync 433268,894121,615120 bobo

       In this example, the particular token produced the three consecutive passwords 433268,
       894121, and 615120. Note that the password sequence string that follows the -sync flag is
       a single argument that cannot have any embedded spaces. If the key for this token is
       19c0a3519a89b4a8034c5b9306db, the next password generated by this token should be 544323
       (with counter value 13). This can be verified using -hotp-show:

           % dacstoken -hotp-show 5 -counter 10 -key 19c0a3519a89b4a8034c5b9306db
           000000000000000a: 433268
           000000000000000b: 894121
           000000000000000c: 615120
           000000000000000d: 544323
           000000000000000e: 002442

       To enable the account for user bobo:

           % dacstoken -uj EXAMPLE -enable -set bobo

       To both set the PIN and enable the account for user bobo:

           % dacstoken -uj EXAMPLE -enable -pin "CzAy" -set bobo

       To list all accounts in detail:

           % dacstoken -uj EXAMPLE -long

       The -list flag is redundant because it is the default operation. The -mode, -counter, etc.
       modifiers have no effect when listing.

       To list only the account for bobo:

           % dacstoken -uj EXAMPLE -list bobo

       The exit status will be non-zero if this user does not have an account.

       To display the account for the device with serial number 37000752:

           % dacstoken -uj EXAMPLE -serial 37000752

       The serial number, which should uniquely identify a token, is often printed on the token
       or can be displayed by the token.

       To set the counter value for the existing account of bobo:

           % dacstoken -uj EXAMPLE -counter 9 -set bobo

       This operation might be used for testing or with a software token. The -sync operation is
       more appropriate for a hardware token.

       To change the PIN for username bobo:

           % dacstoken -uj EXAMPLE -pin-prompt -set bobo

       The program will prompt for the new PIN.

       To use an alternate account file, /secure/auth_tokens:

           % dacstoken -uj EXAMPLE -vfs "dacs-kwv-fs:/secure/auth_tokens" -list

       To use new keys (making the same assumptions as earlier), add a suitable VFS directive to
       dacs.conf; the default defines the item type auth_token_keys_prev as follows:

           VFS "[auth_token_keys_prev]dacs-fs:${Conf::FEDERATIONS_ROOT}/\

           % cd /usr/local/dacs/federations_root/
           % mv auth_token_keys auth_token_keys.prev
           % dacskey -uj EXAMPLE -q auth_token_keys
           % chgrp www auth_token_keys
           % chmod 0640 auth_token_keys
           % dacstoken -uj EXAMPLE -inkeys auth_token_keys.prev -set


       The program exits 0, or 1 if an error occurred.


       HOTP should probably be called COTP, but HOTP came before TOTP.  WOTP?

       Listings may only be sorted by username.

       The drift adjustment for TOTP accounts is tied to the real time clocks of a particular
       client/server pair. If either clock is effectively changed "too much" (e.g., by resetting
       a very fast server clock or replacing an old token that had a relatively slower clock),
       then a user will observe the token to suddenly stop working. Resynchronization is required
       in these cases. Sharing an account file amongst two or more servers should be avoided in
       general (because locks are unlikely to be visible across hosts), but also if their clocks
       are not always well synchronized. It is recommended that the Network Time Protocol (RFC
       1305[37]) or equivalent be used on any host that runs DACS commands or web services.

       The implementation of time-based tokens is based on the latest available Internet-Draft,
       which is considered by the IETF to be a "work in progress". Hence the algorithm, its
       implementation (including DACS accounts based on this operational mode), and documentation
       are all subject to change.

       TOTP password matching windows are symmetrical.

       This functionality should probably be available through dacs_admin(8)[38] and
       dacsauth(1)[39], but it's not.

       Mutual authentication using tokens should be implemented.

       Although release 1.4.25 introduced many improvements, some cause incompatibilities with
       earlier versions of dacstoken.


       RFC 4226[4], draft-mraihi-totp-timebased-05.txt[5], dacs_authenticate(8)[2],
       dacs_token(8)[8], dacsgrid(1)[40], dacspasswd(1)[10], opie(4)[41], Mobile One Time
       Passwords[42], mod_authn_otp[43]


       Distributed Systems Software ([44])


       Our sincere thanks to Authenex, Inc.[24] and HyperSecu Information Systems, Inc.[26] for
       generously providing samples of their products and technical support.


       Copyright2003-2013 Distributed Systems Software. See the LICENSE[45] file that accompanies
       the distribution for licensing information.


        1. dacsoptions

        2. dacs_authenticate

        3. local_token_authenticate

        4. RFC 4226

        5. latest IETF Internet-Draft

        6. Additional operational modes

        7. -convert flag

        8. dacs_token(8)


       10. dacspasswd(1)

       11. dacs_passwd(8)




       15. RFC 2104

       16. FIPS 198

       17. time(3)

       18. dacsexpr(1)

       19. man-in-the-middle attack

       20. revocation list

       21. local_passwd_authenticate

       22. DACS identities

       23. dacskey(1)

       24. Authenex A-Key 3600

       25. Feitian Technologies

       26. HyperSecu Information Systems

       27. OATH Token

       28. iPod Touch, iPhone, and iPad

       29. iOATH Lite

       30. Photo

       31. -validate

       32. -set

       33. VFS

       34. Tokens and secret keys

       35. XML record

       36. -import

       37. RFC 1305

       38. dacs_admin(8)

       39. dacsauth(1)

       40. dacsgrid(1)

       41. opie(4)

       42. Mobile One Time Passwords

       43. mod_authn_otp


       45. LICENSE