SCard Lua Reference Documentation
chilkat.SCard
Current Version: 11.7.0
Markdown version of this page for AI tools (v 11.7.0) · all AI docs
Chilkat.SCard
Enumerate available PC/SC smart card readers and identify the reader the
application should use.
Connect to a reader/card, check card presence and status, and manage the
active PC/SC connection.
Send APDU commands directly to the card and receive the raw response
bytes and status words.
Issue lower-level reader control commands when supported by the reader
driver and PC/SC environment.
Monitor reader or card status changes so applications can detect card
insertion, removal, or state changes.
Use PC/SC transactions for coordinated card access and inspect detailed
error information when reader or card operations fail.
For an extended overview, see
SCard Class Overview.
Communicate directly with smart card readers and cards through PC/SC.
Chilkat.SCard is the low-level PC/SC smart card interface for
applications that need direct reader and card communication. It supports
reader discovery, reader connection, card status checking, APDU transmission,
reader-control commands, status-change monitoring, transactions, and
diagnostic access to underlying PC/SC errors. Use this class when the
application needs APDU-level control rather than a higher-level certificate,
minidriver, or PKCS#11 abstraction.
Reader discovery
Connect to cards
Transmit APDUs
Reader-control commands
Status monitoring
Transactions and diagnostics
Chilkat.SCard for direct PC/SC
reader and APDU-level work; use Chilkat.ScMinidriver for
card-minidriver certificate and key-container operations, and
Chilkat.Pkcs11 for PKCS#11 token or HSM sessions.
Object Creation
local chilkat = require("chilkat")
local scard = chilkat.SCard.new()Creates the object (chilkat.SCard() does the same). Lua's garbage collector frees it when it is no longer referenced; scard:dispose() frees it at once, and in Lua 5.4 and later local scard <close> = chilkat.SCard.new() frees it when the block ends. Calling a method of a disposed object raises an error.
Errors
A method that fails returns nil followed by the error text, as io.open does: local body, err = scard:method(...), where err is the object's last_error_text. Wrap the call in assert() to raise an error with that text instead. Methods that answer a question return true or false, numbers are returned as they are (check last_method_success where the description says a value means failure), and property reads and writes never fail for Chilkat reasons.
Misuse raises a Lua error: a wrong argument type or a missing argument (bad argument #1 to ...), an unknown property name, a write to a read-only property, an out-of-range integer, or an object of the wrong class.
Names are Chilkat's in snake_case: QuickGetStr is quick_get_str, LastErrorText is last_error_text. Properties are fields (scard.verbose_logging = true) and methods use the colon (scard:method(...)). Strings are UTF-8; binary data is a Lua string of bytes. Indexes are 0-based, as in every Chilkat API. Unlocking: call chilkat.unlock_bundle("...") once at startup.
Properties
ActiveProtocol
local strVal = scard.active_protocol
The name of the active protocol if connected smart card reader, or an empty string if not connected. Possible values are T0, T1, raw, undefined, or if not connected to a reader.
CardAtr
local strVal = scard.card_atr
This is the Current ATR of a card in the connected reader.
topConnectedReader
local strVal = scard.connected_reader
The name of the currently connected smart card reader, or an empty string if not connected.
topContext
local strVal = scard.context
Contains the string user or system if this object has established a context (by calling EstablishContext). Contains the empty string if no context is established.
DebugLogFilePath
local strVal = scard.debug_log_file_path
scard.debug_log_file_path = strVal
If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.
Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.
Possible causes of hangs include:
- A timeout property set to 0, indicating an infinite timeout.
- A hang occurring within an event callback in the application code.
- An internal bug in the Chilkat code causing the hang.
LastErrorHtml
local strVal = scard.last_error_html
Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastErrorText
local strVal = scard.last_error_text
Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
LastErrorXml
local strVal = scard.last_error_xml
Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastMethodSuccess
local boolVal = scard.last_method_success
scard.last_method_success = boolVal
Indicates the success or failure of the most recent method call: true means success, false means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.
PcscLibPath
local strVal = scard.pcsc_lib_path
scard.pcsc_lib_path = strVal
For Linux systems only. Specifies the full path of the libpcsclite.so shared lib. This property should only be used if the libpcsclite.so is in a non-standard location or if Chilkat cannot automatically located it.
topReaderStatus
local strVal = scard.reader_status
The current status of the connected reader. Possible values are:
absent- There is no card in the reader.present- There is a card in the reader, but it has not been moved into position for use.swallowed- There is a card in the reader in position for use. The card is not powered.powered- Power is being provided to the card, but the reader driver is unaware of the mode of the card.negotiable- The card has been reset and is awaiting PTS negotiation.specific- The card has been reset and specific communication protocols have been established.
ScardError
local strVal = scard.scard_error
The last error returned by an underlying PC/SC function. Can be one of the following:
SCARD_W_REMOVED_CARD- The smart card has been removed, so that further communication is not possible.SCARD_W_RESET_CARD- The smart card has been reset, so any shared state information is invalid.
...
VerboseLogging
local boolVal = scard.verbose_logging
scard.verbose_logging = boolVal
If set to true, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
Version
local strVal = scard.version
Methods
BeginTransaction
local ok, err = scard:begin_transaction()
Establishes a temporary exclusive access mode for doing a series of commands in a transaction.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
CheckStatus
local flag = scard:check_status()
Check the current status of the currently connected reader. Calling this method updates the ReaderStatus, ActiveProtocol, and CardAtr properties. If this method returns false, none of the properties are updated.
Returns true or false: an answer, not a success flag.
Connect
-- share_mode is a string
-- preferred_protocol is a string
-- flag is true or false
local flag = scard:connect(reader, share_mode, preferred_protocol)
Establish a connection to a reader. The reader is the name of a reader returned from ListReaders. The share_mode can be shared, exclusive, or direct. The preferred_protocol can be 0 (valid only if the shareMode = direct), T0, T1, raw, or no_preference. (No preference is effectively T0 or T1.)
If successful, the state of this object instance is that it's connected to the reader.
Returns true or false: an answer, not a success flag.
Disconnect
-- ok is true, or nil and err on failure
local ok, err = scard:disconnect(disposition)
Terminates a connection with a reader. The disposition can be one of the following values:
leave: Do nothing.reset: Reset the card (warm reset).unpower: Power down the card (cold reset).eject: Eject the card.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
EndTransaction
-- ok is true, or nil and err on failure
local ok, err = scard:end_transaction(disposition)
Ends a previously begun transaction. The disposition is the action to be taken on the reader, and can be leave which is to do nothing, reset, unpower, or eject.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
EstablishContext
-- ok is true, or nil and err on failure
local ok, err = scard:establish_context(scope)
Creates an Application Context to the PC/SC Resource Manager. This must be the first WinSCard function called in a PC/SC application. The scope can be user or system. After calling, this object will have context and all other methods will use the established context. The Context property will hold the value user or system if context was established, or will be empty if no context was established.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
FindSmartcards
-- ok is true, or nil and err on failure
local ok, err = scard:find_smartcards(json)
Returns JSON containing information about the smartcards currently inserted into readers.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
GetAttrib
-- bd is a chilkat.BinData
-- ok is true, or nil and err on failure
local ok, err = scard:get_attrib(attr, bd)
Get an attribute from the IFD Handler (reader driver).
The attr can be one of the following:
ASYNC_PROTOCOL_TYPESATR_STRINGCHANNEL_IDCHARACTERISTICSCURRENT_BWTCURRENT_CLKCURRENT_CWTCURRENT_DCURRENT_EBC_ENCODINGCURRENT_FCURRENT_IFSCCURRENT_IFSDCURRENT_IO_STATECURRENT_NCURRENT_PROTOCOL_TYPECURRENT_WDEFAULT_CLKDEFAULT_DATA_RATEDEVICE_FRIENDLY_NAMEDEVICE_IN_USEDEVICE_SYSTEM_NAMEDEVICE_UNITESC_AUTHREQUESTESC_CANCELESC_RESETEXTENDED_BWTICC_INTERFACE_STATUSICC_PRESENCEICC_TYPE_PER_ATRMAX_CLKMAX_DATA_RATEMAX_IFSDMAXINPUTPOWER_MGMT_SUPPORTSUPRESS_T1_IFS_REQUESTSYNC_PROTOCOL_TYPESUSER_AUTH_INPUT_DEVICEUSER_TO_CARD_AUTH_DEVICEVENDOR_IFD_SERIAL_NOVENDOR_IFD_TYPEVENDOR_IFD_VERSIONVENDOR_NAME
The attribute data is returned in bd.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
GetAttribStr
-- str is a string, or nil and err on failure
local str, err = scard:get_attrib_str(attr)
Get a string typed attribute from the IFD Handler (reader driver).
The attr can be one of the following, but should be limited to the particular attributes that return string values.
ASYNC_PROTOCOL_TYPESATR_STRINGCHANNEL_IDCHARACTERISTICSCURRENT_BWTCURRENT_CLKCURRENT_CWTCURRENT_DCURRENT_EBC_ENCODINGCURRENT_FCURRENT_IFSCCURRENT_IFSDCURRENT_IO_STATECURRENT_NCURRENT_PROTOCOL_TYPECURRENT_WDEFAULT_CLKDEFAULT_DATA_RATEDEVICE_FRIENDLY_NAMEDEVICE_IN_USEDEVICE_SYSTEM_NAMEDEVICE_UNITESC_AUTHREQUESTESC_CANCELESC_RESETEXTENDED_BWTICC_INTERFACE_STATUSICC_PRESENCEICC_TYPE_PER_ATRMAX_CLKMAX_DATA_RATEMAX_IFSDMAXINPUTPOWER_MGMT_SUPPORTSUPRESS_T1_IFS_REQUESTSYNC_PROTOCOL_TYPESUSER_AUTH_INPUT_DEVICEUSER_TO_CARD_AUTH_DEVICEVENDOR_IFD_SERIAL_NOVENDOR_IFD_TYPEVENDOR_IFD_VERSIONVENDOR_NAME
Returns the string, or nil, err on failure (or when nothing is found). The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
GetAttribUint
-- n is an integer
local n = scard:get_attrib_uint(attr)
Get an unsigned integer typed attribute from the IFD Handler (reader driver).
The attr can be one of the following, but should be limited to the particular attributes that return unsigned integer values.
ASYNC_PROTOCOL_TYPESATR_STRINGCHANNEL_IDCHARACTERISTICSCURRENT_BWTCURRENT_CLKCURRENT_CWTCURRENT_DCURRENT_EBC_ENCODINGCURRENT_FCURRENT_IFSCCURRENT_IFSDCURRENT_IO_STATECURRENT_NCURRENT_PROTOCOL_TYPECURRENT_WDEFAULT_CLKDEFAULT_DATA_RATEDEVICE_FRIENDLY_NAMEDEVICE_IN_USEDEVICE_SYSTEM_NAMEDEVICE_UNITESC_AUTHREQUESTESC_CANCELESC_RESETEXTENDED_BWTICC_INTERFACE_STATUSICC_PRESENCEICC_TYPE_PER_ATRMAX_CLKMAX_DATA_RATEMAX_IFSDMAXINPUTPOWER_MGMT_SUPPORTSUPRESS_T1_IFS_REQUESTSYNC_PROTOCOL_TYPESUSER_AUTH_INPUT_DEVICEUSER_TO_CARD_AUTH_DEVICEVENDOR_IFD_SERIAL_NOVENDOR_IFD_TYPEVENDOR_IFD_VERSIONVENDOR_NAME
Returns 0xFFFFFFFF on failure.
topGetStatusChange
-- st_reader_names is a chilkat.StringTable
-- json is a chilkat.JsonObject
-- ok is true, or nil and err on failure
local ok, err = scard:get_status_change(max_wait_ms, st_reader_names, json)
Blocks execution until the current availability of the cards in a specific set of readers changes.
This function receives a list of reader names in st_reader_names. It then blocks waiting for a change in state to occur for a maximum blocking time of max_wait_ms (in milliseconds) or forever if 0 is used.
Information about the current reader states and which reader(s) changed is returned in json. See the example below for more information.
To wait for a reader event (reader added or removed) you may use the special reader name \\?PnP?\Notification.
To cancel the ongoing call, call Cancel().
The st_reader_names contains the reader names to check. The json is empty on input, and if the call returns success contains information about the state (after the event change) of each reader.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
GetStatusChangeCancel
local ok, err = scard:get_status_change_cancel()
Cancels an ongoing GetStatusChange method call. This would be called from a separate thread in your application if GetStatusChange was called synchronously.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
ListReaderGroups
-- ok is true, or nil and err on failure
local ok, err = scard:list_reader_groups(reader_groups)
Returns a list of currently available reader groups on the system. The reader groups are returned in reader_groups.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
ListReaders
-- ok is true, or nil and err on failure
local ok, err = scard:list_readers(st)
Returns a list of currently available readers on the system.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
Reconnect
-- preferred_protocol is a string
-- action is a string
-- ok is true, or nil and err on failure
local ok, err = scard:reconnect(share_mode, preferred_protocol, action)
Reestablishes a connection to a reader that was previously connected to using Connect().
In a multi application environment it is possible for an application to reset the card in shared mode. When this occurs any other application trying to access certain commands will be returned the value SCARD_W_RESET_CARD. When this occurs Reconnect() must be called in order to acknowledge that the card was reset and allow it to change its state accordingly.
The share_mode can be shared, exclusive, or direct. The preferred_protocol can be 0 (valid only if the shareMode = direct), T0, T1, raw, or no_preference. (No preference is effectively T0 or T1.) The action is the desired action taken on the card/reader. It can be leave, reset, unpower, or eject.
If successful, the state of this object instance is that it's connected to the reader.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
ReleaseContext
local ok, err = scard:release_context()
Destroys a communication context to the PC/SC Resource Manager. This must be the last function called in a PC/SC application.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
SendControl
-- bd_send is a chilkat.BinData
-- bd_recv is a chilkat.BinData
-- ok is true, or nil and err on failure
local ok, err = scard:send_control(control_code, bd_send, bd_recv)
Sends a command directly to the IFD Handler (reader driver) to be processed by the reader.
This is useful for creating client side reader drivers for functions like PIN pads, biometrics, or other extensions to the normal smart card reader that are not normally handled by PC/SC.
The command data is sent in bd_send. The response is written to bd_recv.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
SendControlHex
-- send_data is a string
-- bd_recv is a chilkat.BinData
-- ok is true, or nil and err on failure
local ok, err = scard:send_control_hex(control_code, send_data, bd_recv)
Sends a command directly to the IFD Handler (reader driver) to be processed by the reader.
This is useful for creating client side reader drivers for functions like PIN pads, biometrics, or other extensions to the normal smart card reader that are not normally handled by PC/SC.
The command data is provided as a hex string in send_data. The response is written to bd_recv.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
Transmit
-- bd_send is a chilkat.BinData
-- bd_recv is a chilkat.BinData
-- max_recv_len is an integer
-- ok is true, or nil and err on failure
local ok, err = scard:transmit(protocol_name, bd_send, bd_recv, max_recv_len)
Sends an APDU to the smart card contained in the currently connected reader. The protocol_name can be T0, T1, or raw. The APDU to be sent is contained in bd_send. The response from the card is contained in bd_recv. The max_recv_len is the maximum response size (in bytes) willing to be accepted.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
TransmitHex
-- apdu_hex is a string
-- bd_recv is a chilkat.BinData
-- max_recv_len is an integer
-- ok is true, or nil and err on failure
local ok, err = scard:transmit_hex(protocol_name, apdu_hex, bd_recv, max_recv_len)
Sends an APDU to the smart card contained in the currently connected reader. The protocol_name can be T0, T1, or raw. The APDU (in hexadecimal) to be sent is passed in apdu_hex. The response from the card is contained in bd_recv. The max_recv_len is the maximum response size (in bytes) willing to be accepted.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
Events
All Chilkat methods are synchronous: the call returns when the work is done. During a long-running call, chilkat.SCard reports progress to the functions given to set_event_handler, in a table keyed by event name (plain functions, not methods: closures carry whatever state they need):
scard:set_event_handler({
percent_done = function(pct) print(pct .. "%") end, -- return true to abort
progress_info = function(name, value) print(name, value) end,
})Installs the handlers, replacing any installed before; scard:set_event_handler(nil) removes them. The event names are checked when the table is installed: a misspelled one raises an error.
The abort_check handler is called periodically during long operations; percent_done is called when an operation's completion percentage is known; progress_info delivers named progress values. A true return from abort_check or percent_done aborts the running method, which then fails in the usual way (nil, err). An error raised in a handler aborts the method and is raised again from the method call; the object remains usable.
AbortCheck
scard:set_event_handler({ abort_check = function() ... end })
Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the HeartbeatMs property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.
Example
local deadline = os.time() + 30 -- give up after 30 seconds
scard:set_event_handler({ abort_check = function() return os.time() > deadline end })PercentDone
scard:set_event_handler({ percent_done = function(pct_done) ... end })
This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).
The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.
To abort the operation, set the abort output argument to true. This will cause the method to terminate and return a failure status or corresponding failure value.
Example
scard:set_event_handler({
percent_done = function(pct_done) -- 0 to 100
print("Percent done: " .. pct_done)
return false -- return true to abort the method in progress
end,
})ProgressInfo
scard:set_event_handler({ progress_info = function(name, value) ... end })
This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.
Note: Some Chilkat methods don't fire any ProgressInfo events.
Example
scard:set_event_handler({
progress_info = function(name, value) print(name .. ": " .. value) end,
})