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File::KDBX - Encrypted database to store secret text and files


version 0.906


    use File::KDBX;

    # Create a new database from scratch
    my $kdbx = File::KDBX->new;

    # Add some objects to the database
    my $group = $kdbx->add_group(
        name => 'Passwords',
    my $entry = $group->add_entry(
        title    => 'My Bank',
        username => 'mreynolds',
        password => 's3cr3t',

    # Save the database to the filesystem
    $kdbx->dump_file('passwords.kdbx', 'masterpw changeme');

    # Load the database from the filesystem into a new database instance
    my $kdbx2 = File::KDBX->load_file('passwords.kdbx', 'masterpw changeme');

    # Iterate over database entries, print entry titles
    $kdbx2->entries->each(sub($entry, @) {
        say 'Entry: ', $entry->title;

See "RECIPES" for more examples.


File::KDBX provides everything you need to work with KDBX databases. A KDBX database is a hierarchical object database which is commonly used to store secret information securely. It was developed for the KeePass password safe. See "Introduction to KDBX" for more information about KDBX.

This module lets you query entries, create new entries, delete entries, modify entries and more. The distribution also includes various parsers and generators for serializing and persisting databases.

The design of this software was influenced by the KeePassXC implementation of KeePass as well as the File::KeePass module. File::KeePass is an alternative module that works well in most cases but has a small backlog of bugs and security issues and also does not work with newer KDBX version 4 files. If you're coming here from the File::KeePass world, you might be interested in File::KeePass::KDBX that is a drop-in replacement for File::KeePass that uses File::KDBX for storage.

This software is a pre-1.0 release. The interface should be considered pretty stable, but there might be minor changes up until a 1.0 release. Breaking changes will be noted in the Changes file.


Introduction to KDBX

A KDBX database consists of a tree of groups and entries, with a single root group. Entries can contain zero or more key-value pairs of strings and zero or more binaries (i.e. octet strings). Groups, entries, strings and binaries: that's the KDBX vernacular. A small amount of metadata (timestamps, etc.) is associated with each entry, group and the database as a whole.

You can think of a KDBX database kind of like a file system, where groups are directories, entries are files, and strings and binaries make up a file's contents.

Databases are typically persisted as encrypted, compressed files. They are usually accessed directly (i.e. not over a network). The primary focus of this type of database is data security. It is ideal for storing relatively small amounts of data (strings and binaries) that must remain secret except to such individuals as have the correct master key. Even if the database file were to be "leaked" to the public Internet, it should be virtually impossible to crack with a strong key. The KDBX format is most often used by password managers to store passwords so that users can know a single strong password and not have to reuse passwords across different websites. See "SECURITY" for an overview of security considerations.










Hash of UUIDs for objects that have been deleted. This includes groups, entries and even custom icons.


Bytes contained within the encrypted layer of a KDBX file. This is only set when using File::KDBX::Loader::Raw.


A text string associated with the database stored unencrypted in the file header. Often unset.


The UUID of a cipher used to encrypt the database when stored as a file.

See File::KDBX::Cipher.


Configuration for whether or not and how the database gets compressed. See ":compression" in File::KDBX::Constants.


The master seed is a string of 32 random bytes that is used as salt in hashing the master key when loading and saving the database. If a challenge-response key is used in the master key, the master seed is also the challenge.

The master seed should be changed each time the database is saved to file.


The transform seed is a string of 32 random bytes that is used in the key derivation function, either as the salt or the key (depending on the algorithm).

The transform seed should be changed each time the database is saved to file.


The number of rounds or iterations used in the key derivation function. Increasing this number makes loading and saving the database slower in order to make dictionary and brute force attacks more costly.


The initialization vector used by the cipher.

The encryption IV should be changed each time the database is saved to file.


The encryption key (possibly including the IV, depending on the cipher) used to encrypt the protected strings within the database.


A string of 32 random bytes written in the header and encrypted in the body. If the bytes do not match when loading a file then the wrong master key was used or the file is corrupt. Only KDBX 2 and KDBX 3 files use this. KDBX 4 files use an improved HMAC method to verify the master key and data integrity of the header and entire file body.


A number indicating the cipher algorithm used to encrypt the protected strings within the database, usually Salsa20 or ChaCha20. See ":random_stream" in File::KDBX::Constants.


A hash/dict of key-value pairs used to configure the key derivation function. This is the KDBX4+ way to configure the KDF, superceding "transform_seed" and "transform_rounds".


The name of the software used to generate the KDBX file.


The header hash used to verify that the file header is not corrupt. (KDBX 2 - KDBX 3.1, removed KDBX 4.0)


Name of the database.


Timestamp indicating when the database name was last changed.


Description of the database


Timestamp indicating when the database description was last changed.


When a new entry is created, the UserName string will be populated with this value.


Timestamp indicating when the default username was last changed.


A color associated with the database (in the form #ffffff where "f" is a hexidecimal digit). Some agents use this to help users visually distinguish between different databases.


Timestamp indicating when the master key was last changed.


Number of days until the agent should prompt to recommend changing the master key.


Number of days until the agent should prompt to force changing the master key.

Note: This is purely advisory. It is up to the individual agent software to actually enforce it. File::KDBX does NOT enforce it.


Array of custom icons that can be associated with groups and entries.

This list can be managed with the methods "add_custom_icon" and "remove_custom_icon".


Boolean indicating whether removed groups and entries should go to a recycle bin or be immediately deleted.


The UUID of a group used to store thrown-away groups and entries.


Timestamp indicating when the recycle bin group was last changed.


The UUID of a group containing template entries used when creating new entries.


Timestamp indicating when the entry templates group was last changed.


The UUID of the previously-selected group.


The UUID of the group visible at the top of the list.


The maximum number of historical entries that should be kept for each entry. Default is 10.


The maximum total size (in bytes) that each individual entry's history is allowed to grow. Default is 6 MiB.


The maximum age (in days) historical entries should be kept. Default it 365.


Timestamp indicating when the database settings were last updated.


Alias of the "memory_protection" setting for the Title string.


Alias of the "memory_protection" setting for the UserName string.


Alias of the "memory_protection" setting for the Password string.


Alias of the "memory_protection" setting for the URL string.


Alias of the "memory_protection" setting for the Notes string.



    $kdbx = File::KDBX->new(%attributes);
    $kdbx = File::KDBX->new($kdbx); # copy constructor

Construct a new File::KDBX.


    $kdbx = $kdbx->init(%attributes);

Initialize a File::KDBX with a set of attributes. Returns itself to allow method chaining.

This is called by "new".


    $kdbx = $kdbx->reset;

Set a File::KDBX to an empty state, ready to load a KDBX file or build a new one. Returns itself to allow method chaining.


    $kdbx_copy = $kdbx->clone;
    $kdbx_copy = File::KDBX->new($kdbx);

Clone a File::KDBX. The clone will be an exact copy and completely independent of the original.





    $kdbx = KDBX::File->load(\$string, $key);
    $kdbx = KDBX::File->load(*IO, $key);
    $kdbx = KDBX::File->load($filepath, $key);
    $kdbx->load(...);           # also instance method

    $kdbx = File::KDBX->load_string($string, $key);
    $kdbx = File::KDBX->load_string(\$string, $key);
    $kdbx->load_string(...);    # also instance method

    $kdbx = File::KDBX->load_file($filepath, $key);
    $kdbx->load_file(...);      # also instance method

    $kdbx = File::KDBX->load_handle($fh, $key);
    $kdbx = File::KDBX->load_handle(*IO, $key);
    $kdbx->load_handle(...);    # also instance method

Load a KDBX file from a string buffer, IO handle or file from a filesystem.

File::KDBX::Loader does the heavy lifting.





    $kdbx->dump(\$string, $key);
    $kdbx->dump(*IO, $key);
    $kdbx->dump($filepath, $key);

    $kdbx->dump_string(\$string, $key);
    \$string = $kdbx->dump_string($key);

    $kdbx->dump_file($filepath, $key);

    $kdbx->dump_handle($fh, $key);
    $kdbx->dump_handle(*IO, $key);

Dump a KDBX file to a string buffer, IO handle or file in a filesystem.

File::KDBX::Dumper does the heavy lifting.


    $string = $kdbx->user_agent_string;

Get a text string identifying the database client software.


    \%settings = $kdbx->memory_protection

    $bool = $kdbx->memory_protection($string_key);
    $kdbx->memory_protection($string_key => $bool);

Get or set memory protection settings. This globally (for the whole database) configures whether and which of the standard strings should be memory-protected. The default setting is to memory-protect only Password strings.

Memory protection can be toggled individually for each entry string, and individual settings take precedence over these global settings.


    $version = $kdbx->minimum_version;

Determine the minimum file version required to save a database losslessly. Using certain databases features might increase this value. For example, setting the KDF to Argon2 will increase the minimum version to at least KDBX_VERSION_4_0 (i.e. 0x00040000) because Argon2 was introduced with KDBX4.

This method never returns less than KDBX_VERSION_3_1 (i.e. 0x00030001). That file version is so ubiquitous and well-supported, there are seldom reasons to dump in a lesser format nowadays.

WARNING: If you dump a database with a minimum version higher than the current "version", the dumper will typically issue a warning and automatically upgrade the database. This seems like the safest behavior in order to avoid data loss, but lower versions have the benefit of being compatible with more software. It is possible to prevent auto-upgrades by explicitly telling the dumper which version to use, but you do run the risk of data loss. A database will never be automatically downgraded.


    $group = $kdbx->root;

Get or set a database's root group. You don't necessarily need to explicitly create or set a root group because it autovivifies when adding entries and groups to the database.

Every database has only a single root group at a time. Some old KDB files might have multiple root groups. When reading such files, a single implicit root group is created to contain the actual root groups. When writing to such a format, if the root group looks like it was implicitly created then it won't be written and the resulting file might have multiple root groups, as it was before loading. This allows working with older files without changing their written internal structure while still adhering to modern semantics while the database is opened.

The root group of a KDBX database contains all of the database's entries and other groups. If you replace the root group, you are essentially replacing the entire database contents with something else.


    \@lineage = $kdbx->trace_lineage($group);
    \@lineage = $kdbx->trace_lineage($group, $base_group);
    \@lineage = $kdbx->trace_lineage($entry);
    \@lineage = $kdbx->trace_lineage($entry, $base_group);

Get the direct line of ancestors from $base_group (default: the root group) to a group or entry. The lineage includes the base group but not the target group or entry. Returns undef if the target is not in the database structure.


    $group = $kdbx->recycle_bin;

Get or set the recycle bin group. Returns undef if there is no recycle bin and "recycle_bin_enabled" is false, otherwise the current recycle bin or an autovivified recycle bin group is returned.


    $group = $kdbx->entry_templates;

Get or set the entry templates group. May return undef if unset.


    $group = $kdbx->last_selected;

Get or set the last selected group. May return undef if unset.


    $group = $kdbx->last_top_visible;

Get or set the last top visible group. May return undef if unset.


    $kdbx->add_group(%group_attributes, %options);

Add a group to a database. This is equivalent to identifying a parent group and calling "add_group" in File::KDBX::Group on the parent group, forwarding the arguments. Available options:

  • group - Group object or group UUID to add the group to (default: root group)


    \&iterator = $kdbx->groups(%options);
    \&iterator = $kdbx->groups($base_group, %options);

Get an File::KDBX::Iterator over groups within a database. Options:

  • base - Only include groups within a base group (same as $base_group) (default: "root")

  • inclusive - Include the base group in the results (default: true)

  • algorithm - Search algorithm, one of ids, bfs or dfs (default: ids)


    $kdbx->add_entry($entry, %options);
    $kdbx->add_entry(%entry_attributes, %options);

Add an entry to a database. This is equivalent to identifying a parent group and calling "add_entry" in File::KDBX::Group on the parent group, forwarding the arguments. Available options:

  • group - Group object or group UUID to add the entry to (default: root group)


    \&iterator = $kdbx->entries(%options);
    \&iterator = $kdbx->entries($base_group, %options);

Get an File::KDBX::Iterator over entries within a database. Supports the same options as "groups", plus some new ones:

  • auto_type - Only include entries with auto-type enabled (default: false, include all)

  • searching - Only include entries within groups with searching enabled (default: false, include all)

  • history - Also include historical entries (default: false, include only current entries)


    \&iterator = $kdbx->objects(%options);
    \&iterator = $kdbx->objects($base_group, %options);

Get an File::KDBX::Iterator over objects within a database. Groups and entries are considered objects, so this is essentially a combination of "groups" and "entries". This won't often be useful, but it can be convenient for maintenance tasks. This method takes the same options as "groups" and "entries".


    \%icon = $kdbx->custom_icon($uuid);
    $kdbx->custom_icon($uuid => \%icon);
    $kdbx->custom_icon(uuid => $value, %icon);

Get or set custom icons.


    $image_data = $kdbx->custom_icon_data($uuid);

Get a custom icon image data.


    $uuid = $kdbx->add_custom_icon($image_data, %attributes);
    $uuid = $kdbx->add_custom_icon(%attributes);

Add a custom icon and get its UUID. If not provided, a random UUID will be generated. Possible attributes:

  • uuid - Icon UUID (default: autogenerated)

  • data - Image data (same as $image_data)

  • name - Name of the icon (text, KDBX4.1+)

  • last_modification_time - Just what it says (datetime, KDBX4.1+)



Remove a custom icon.


    \%all_data = $kdbx->custom_data;

    \%data = $kdbx->custom_data($key);
    $kdbx->custom_data($key => \%data);
    $kdbx->custom_data(key => $value, %data);

Get and set custom data. Custom data is metadata associated with a database.

Each data item can have a few attributes associated with it.

  • key - A unique text string identifier used to look up the data item (required)

  • value - A text string value (required)

  • last_modification_time (optional, KDBX4.1+)


    $value = $kdbx->custom_data_value($key);

Exactly the same as "custom_data" except returns just the custom data's value rather than a structure of attributes. This is a shortcut for:

    my $data = $kdbx->custom_data($key);
    my $value = defined $data ? $data->{value} : undef;


    \%all_data = $kdbx->public_custom_data;

    $value = $kdbx->public_custom_data($key);
    $kdbx->public_custom_data($key => $value);

Get and set public custom data. Public custom data is similar to custom data but different in some important ways. Public custom data:

  • can store strings, booleans and up to 64-bit integer values (custom data can only store text values)

  • is NOT encrypted within a KDBX file (hence the "public" part of the name)

  • is a plain hash/dict of key-value pairs with no other associated fields (like modification times)



Add a UUID to the deleted objects list. This list is used to support automatic database merging.

You typically do not need to call this yourself because the list will be populated automatically as objects are removed.



Remove a UUID from the deleted objects list. This list is used to support automatic database merging.

You typically do not need to call this yourself because the list will be maintained automatically as objects are added.


Remove all UUIDs from the deleted objects list. This list is used to support automatic database merging, but if you don't need merging then you can clear deleted objects to reduce the database file size.


    $string = $kdbx->resolve_reference($reference);
    $string = $kdbx->resolve_reference($wanted, $search_in, $expression);

Resolve a field reference. A field reference is a kind of string placeholder. You can use a field reference to refer directly to a standard field within an entry. Field references are resolved automatically while expanding entry strings (i.e. replacing placeholders), but you can use this method to resolve on-the-fly references that aren't part of any actual string in the database.

If the reference does not resolve to any field, undef is returned. If the reference resolves to multiple fields, only the first one is returned (in the same order as iterated by "entries"). To avoid ambiguity, you can refer to a specific entry by its UUID.

The syntax of a reference is: {REF:<WantedField>@<SearchIn>:<Text>}. Text is a "Simple Expression". WantedField and SearchIn are both single character codes representing a field:

  • T - Title

  • U - UserName

  • P - Password

  • A - URL

  • N - Notes

  • I - UUID

  • O - Other custom strings

Since O does not represent any specific field, it cannot be used as the WantedField.


To get the value of the UserName string of the first entry with "My Bank" in the title:

    my $username = $kdbx->resolve_reference('{REF:U@T:"My Bank"}');
    # OR the {REF:...} wrapper is optional
    my $username = $kdbx->resolve_reference('U@T:"My Bank"');
    # OR separate the arguments
    my $username = $kdbx->resolve_reference(U => T => '"My Bank"');

Note how the text is a "Simple Expression", so search terms with spaces must be surrounded in double quotes.

To get the Password string of a specific entry (identified by its UUID):

    my $password = $kdbx->resolve_reference('{REF:P@I:46C9B1FFBD4ABC4BBB260C6190BAD20C}');



Encrypt all protected strings and binaries in a database. The encrypted data is stored in a File::KDBX::Safe associated with the database and the actual values will be replaced with undef to indicate their protected state. Returns itself to allow method chaining.

You can call lock on an already-locked database to memory-protect any unprotected strings and binaries added after the last time the database was locked.



Decrypt all protected strings and binaries in a database, replacing undef value placeholders with their actual, unprotected values. Returns itself to allow method chaining.


    $guard = $kdbx->unlock_scoped;

Unlock a database temporarily, relocking when the guard is released (typically at the end of a scope). Returns undef if the database is already unlocked.

See "lock" and "unlock".


        my $guard = $kdbx->unlock_scoped;
    # $kdbx is now memory-locked


    $string = $kdbx->peek(\%string);
    $string = $kdbx->peek(\%binary);

Peek at the value of a protected string or binary without unlocking the whole database. The argument can be a string or binary hashref as returned by "string" in File::KDBX::Entry or "binary" in File::KDBX::Entry.


    $bool = $kdbx->is_locked;

Get whether or not a database's contents are in a locked (i.e. memory-protected) state. If this is true, then some or all of the protected strings and binaries within the database will be unavailable (literally have undef values) until "unlock" is called.



Remove groups with no subgroups and no entries.



Remove icons that are not associated with any entry or group in the database.



Remove duplicate icons as determined by hashing the icon data.



Remove just as many older historical entries as necessary to get under certain limits.

  • max_items - Maximum number of historical entries to keep (default: value of "history_max_items", no limit: -1)

  • max_size - Maximum total size (in bytes) of historical entries to keep (default: value of "history_max_size", no limit: -1)

  • max_age - Maximum age (in days) of historical entries to keep (default: value of "maintenance_history_days", no limit: -1)



Set various keys, seeds and IVs to random values. These values are used by the cryptographic functions that secure the database when dumped. The attributes that will be randomized are:

Randomizing these values has no effect on a loaded database. These are only used when a database is dumped. You normally do not need to call this method explicitly because the dumper does it for you by default.


    $key = $kdbx->key;
    $key = $kdbx->key($key);
    $key = $kdbx->key($primitive);

Get or set a File::KDBX::Key. This is the master key (e.g. a password or a key file that can decrypt a database). You can also pass a primitive castable to a Key. See "new" in File::KDBX::Key for an explanation of what the primitive can be.

You generally don't need to call this directly because you can provide the key directly to the loader or dumper when loading or dumping a KDBX file.


    $key = $kdbx->composite_key($key);
    $key = $kdbx->composite_key($primitive);

Construct a File::KDBX::Key::Composite from a Key or primitive. See "new" in File::KDBX::Key for an explanation of what the primitive can be. If the primitive does not represent a composite key, it will be wrapped.

You generally don't need to call this directly. The loader and dumper use it to transform a master key into a raw encryption key.


    $kdf = $kdbx->kdf(%options);
    $kdf = $kdbx->kdf(\%parameters, %options);

Get a File::KDBX::KDF (key derivation function).


  • params - KDF parameters, same as \%parameters (default: value of "kdf_parameters")


    $cipher = $kdbx->cipher(key => $key);
    $cipher = $kdbx->cipher(key => $key, iv => $iv, uuid => $uuid);

Get a File::KDBX::Cipher capable of encrypting and decrypting the body of a database file.

A key is required. This should be a raw encryption key made up of a fixed number of octets (depending on the cipher), not a File::KDBX::Key or primitive.

If not passed, the UUID comes from $kdbx->headers->{cipher_id} and the encryption IV comes from $kdbx->headers->{encryption_iv}.

You generally don't need to call this directly. The loader and dumper use it to decrypt and encrypt KDBX files.


    $cipher = $kdbx->random_stream;
    $cipher = $kdbx->random_stream(id => $stream_id, key => $key);

Get a File::KDBX::Cipher::Stream for decrypting and encrypting protected values.

If not passed, the ID and encryption key comes from $kdbx->headers->{inner_random_stream_id} and $kdbx->headers->{inner_random_stream_key} (respectively) for KDBX3 files and from $kdbx->inner_headers->{inner_random_stream_key} and $kdbx->inner_headers->{inner_random_stream_id} (respectively) for KDBX4 files.

You generally don't need to call this directly. The loader and dumper use it to scramble protected strings.


Create a new database

    my $kdbx = File::KDBX->new;

    my $group = $kdbx->add_group(name => 'Passwords);
    my $entry = $group->add_entry(
        title    => 'WayneCorp',
        username => 'bwayne',
        password => 'iambatman',
        url      => ''
    $entry->add_auto_type_window_association('WayneCorp - Mozilla Firefox', '{PASSWORD}{ENTER}');

    $kdbx->dump_file('mypasswords.kdbx', 'master password CHANGEME');

Read an existing database

    my $kdbx = File::KDBX->load_file('mypasswords.kdbx', 'master password CHANGEME');
    $kdbx->unlock;  # cause $entry->password below to be defined

    $kdbx->entries->each(sub($entry, @) {
        say 'Found password for: ', $entry->title;
        say '  Username: ', $entry->username;
        say '  Password: ', $entry->password;

Search for entries

    my @entries = $kdbx->entries(searching => 1)
        ->grep(title => 'WayneCorp')
        ->each;     # return all matches

The searching option limits results to only entries within groups with searching enabled. Other options are also available. See "entries".

See "QUERY" for many more query examples.

Search for entries by auto-type window association

    my $window_title = 'WayneCorp - Mozilla Firefox';

    my $entries = $kdbx->entries(auto_type => 1)
        ->filter(sub {
            my ($ata) = grep { $_->{window} =~ /\Q$window_title\E/i } @{$_->auto_type_associations};
            return [$_, $ata->{keystroke_sequence}] if $ata;
        ->each(sub {
            my ($entry, $keys) = @$_;
            say 'Entry title: ', $entry->title, ', key sequence: ', $keys;

Example output:

    Entry title: WayneCorp, key sequence: {PASSWORD}{ENTER}

Remove entries from a database

        ->grep(notes => {'=~' => qr/too old/i})
        ->each(sub { $_->recycle });

Recycle all entries with the string "too old" appearing in the Notes string.

Remove empty groups

    $kdbx->groups(algorithm => 'dfs')
        ->where(-true => 'is_empty')

With the search/iteration algorithm set to "dfs", groups will be ordered deepest first and the root group will be last. This allows removing groups that only contain empty groups.

This can also be done with one call to "remove_empty_groups".


One of the biggest threats to your database security is how easily the encryption key can be brute-forced. Strong brute-force protection depends on:

  • Using unguessable passwords, passphrases and key files.

  • Using a brute-force resistent key derivation function.

The first factor is up to you. This module does not enforce strong master keys. It is up to you to pick or generate strong keys.

The KDBX format allows for the key derivation function to be tuned. The idea is that you want each single brute-force attempt to be expensive (in terms of time, CPU usage or memory usage), so that making a lot of attempts (which would be required if you have a strong master key) gets really expensive.

How expensive you want to make each attempt is up to you and can depend on the application.

This and other KDBX-related security issues are covered here more in depth:

Here are other security risks you should be thinking about:


This distribution uses the excellent CryptX and Crypt::Argon2 packages to handle all crypto-related functions. As such, a lot of the security depends on the quality of these dependencies. Fortunately these modules are maintained and appear to have good track records.

The KDBX format has evolved over time to incorporate improved security practices and cryptographic functions. This package uses the following functions for authentication, hashing, encryption and random number generation:

  • AES-128 (legacy)

  • AES-256

  • Argon2d & Argon2id

  • CBC block mode

  • HMAC-SHA256

  • SHA256

  • SHA512

  • Salsa20 & ChaCha20

  • Twofish

At the time of this writing, I am not aware of any successful attacks against any of these functions. These are among the most-analyzed and widely-adopted crypto functions available.

The KDBX format allows the body cipher and key derivation function to be configured. If a flaw is discovered in one of these functions, you can hopefully just switch to a better function without needing to update this software. A later software release may phase out the use of any functions which are no longer secure.

Memory Protection

It is not a good idea to keep secret information unencrypted in system memory for longer than is needed. The address space of your program can generally be read by a user with elevated privileges on the system. If your system is memory-constrained or goes into a hibernation mode, the contents of your address space could be written to a disk where it might be persisted for long time.

There might be system-level things you can do to reduce your risk, like using swap encryption and limiting system access to your program's address space while your program is running.

File::KDBX helps minimize (but not eliminate) risk by keeping secrets encrypted in memory until accessed and zeroing out memory that holds secrets after they're no longer needed, but it's not a silver bullet.

For one thing, the encryption key is stored in the same address space. If core is dumped, the encryption key is available to be found out. But at least there is the chance that the encryption key and the encrypted secrets won't both be paged out together while memory-constrained.

Another problem is that some perls (somewhat notoriously) copy around memory behind the scenes willy nilly, and it's difficult know when perl makes a copy of a secret in order to be able to zero it out later. It might be impossible. The good news is that perls with SvPV copy-on-write (enabled by default beginning with perl 5.20) are much better in this regard. With COW, it's mostly possible to know what operations will cause perl to copy the memory of a scalar string, and the number of copies will be significantly reduced. There is a unit test named t/memory-protection.t in this distribution that can be run on POSIX systems to determine how well File::KDBX memory protection is working.

Memory protection also depends on how your application handles secrets. If your app code is handling scalar strings with secret information, it's up to you to make sure its memory is zeroed out when no longer needed. "erase" in File::KDBX::Util et al. provide some tools to help accomplish this. Or if you're not too concerned about the risks memory protection is meant to mitigate, then maybe don't worry about it. The security policy of File::KDBX is to try hard to keep secrets protected while in memory so that your app might claim a high level of security, in case you care about that.

There are some memory protection strategies that File::KDBX does NOT use today but could in the future:

Many systems allow programs to mark unswappable pages. Secret information should ideally be stored in such pages. You could potentially use mlockall(2) (or equivalent for your system) in your own application to prevent the entire address space from being swapped.

Some systems provide special syscalls for storing secrets in memory while keeping the encryption key outside of the program's address space, like CryptProtectMemory for Windows. This could be a good option, though unfortunately not portable.


To find things in a KDBX database, you should use a filtered iterator. If you have an iterator, such as returned by "entries", "groups" or even "objects" you can filter it using "where" in File::KDBX::Iterator.

    my $filtered_entries = $kdbx->entries->where(\&query);

A \&query is just a subroutine that you can either write yourself or have generated for you from either a "Simple Expression" or "Declarative Syntax". It's easier to have your query generated, so I'll cover that first.

Simple Expression

A simple expression is mostly compatible with the KeePass 2 implementation described here.

An expression is a string with one or more space-separated terms. Terms with spaces can be enclosed in double quotes. Terms are negated if they are prefixed with a minus sign. A record must match every term on at least one of the given fields.

So a simple expression is something like what you might type into a search engine. You can generate a simple expression query using "simple_expression_query" in File::KDBX::Util or by passing the simple expression as a scalar reference to where.

To search for all entries in a database with the word "canyon" appearing anywhere in the title:

    my $entries = $kdbx->entries->where(\'canyon', qw[title]);

Notice the first argument is a scalarref. This disambiguates a simple expression from other types of queries covered below.

As mentioned, a simple expression can have multiple terms. This simple expression query matches any entry that has the words "red" and "canyon" anywhere in the title:

    my $entries = $kdbx->entries->where(\'red canyon', qw[title]);

Each term in the simple expression must be found for an entry to match.

To search for entries with "red" in the title but not "canyon", just prepend "canyon" with a minus sign:

    my $entries = $kdbx->entries->where(\'red -canyon', qw[title]);

To search over multiple fields simultaneously, just list them all. To search for entries with "grocery" (but not "Foodland") in the title or notes:

    my $entries = $kdbx->entries->where(\'grocery -Foodland', qw[title notes]);

The default operator is a case-insensitive regexp match, which is fine for searching text loosely. You can use just about any binary comparison operator that perl supports. To specify an operator, list it after the simple expression. For example, to search for any entry that has been used at least five times:

    my $entries = $kdbx->entries->where(\5, '>=', qw[usage_count]);

It helps to read it right-to-left, like "usage_count is greater than or equal to 5".

If you find the disambiguating structures to be distracting or confusing, you can also use the "simple_expression_query" in File::KDBX::Util function as a more intuitive alternative. The following example is equivalent to the previous:

    my $entries = $kdbx->entries->where(simple_expression_query(5, '>=', qw[usage_count]));

Declarative Syntax

Structuring a declarative query is similar to "WHERE CLAUSES" in SQL::Abstract, but you don't have to be familiar with that module. Just learn by examples here.

To search for all entries in a database titled "My Bank":

    my $entries = $kdbx->entries->where({ title => 'My Bank' });

The query here is { title => 'My Bank' }. A hashref can contain key-value pairs where the key is an attribute of the thing being searched for (in this case an entry) and the value is what you want the thing's attribute to be to consider it a match. In this case, the attribute we're using as our match criteria is "title" in File::KDBX::Entry, a text field. If an entry has its title attribute equal to "My Bank", it's a match.

A hashref can contain multiple attributes. The search candidate will be a match if all of the specified attributes are equal to their respective values. For example, to search for all entries with a particular URL AND username:

    my $entries = $kdbx->entries->where({
        url      => '',
        username => 'neo',

To search for entries matching any criteria, just change the hashref to an arrayref. To search for entries with a particular URL OR username:

    my $entries = $kdbx->entries->where([ # <-- Notice the square bracket
        url      => '',
        username => 'neo',

You can use different operators to test different types of attributes. The "icon_id" in File::KDBX::Entry attribute is a number, so we should use a number comparison operator. To find entries using the smartphone icon:

    my $entries = $kdbx->entries->where({
        icon_id => { '==', ICON_SMARTPHONE },

Note: "ICON_SMARTPHONE" in File::KDBX::Constants is just a constant from File::KDBX::Constants. It isn't special to this example or to queries generally. We could have just used a literal number.

The important thing to notice here is how we wrapped the condition in another hashref with a single key-value pair where the key is the name of an operator and the value is the thing to match against. The supported operators are:

  • eq - String equal

  • ne - String not equal

  • lt - String less than

  • gt - String greater than

  • le - String less than or equal

  • ge - String greater than or equal

  • == - Number equal

  • != - Number not equal

  • < - Number less than

  • > - Number greater than

  • <= - Number less than or equal

  • >= - Number less than or equal

  • =~ - String match regular expression

  • !~ - String does not match regular expression

  • ! - Boolean false

  • !! - Boolean true

Other special operators:

  • -true - Boolean true

  • -false - Boolean false

  • -not - Boolean false (alias for -false)

  • -defined - Is defined

  • -undef - Is not defined

  • -empty - Is empty

  • -nonempty - Is not empty

  • -or - Logical or

  • -and - Logical and

Let's see another example using an explicit operator. To find all groups except one in particular (identified by its "uuid" in File::KDBX::Group), we can use the ne (string not equal) operator:

    my $groups = $kdbx->groups->where(
        uuid => {
            'ne' => uuid('596f7520-6172-6520-7370-656369616c2e'),

Note: "uuid" in File::KDBX::Util is a little utility function to convert a UUID in its pretty form into bytes. This utility function isn't special to this example or to queries generally. It could have been written with a literal such as "\x59\x6f\x75\x20\x61...", but that's harder to read.

Notice we searched for groups this time. Finding groups works exactly the same as it does for entries.

Notice also that we didn't wrap the query in hashref curly-braces or arrayref square-braces. Those are optional. By default it will only match ALL attributes (as if there were curly-braces).

Testing the truthiness of an attribute is a little bit different because it isn't a binary operation. To find all entries with the password quality check disabled:

    my $entries = $kdbx->entries->where('!' => 'quality_check');

This time the string after the operator is the attribute name rather than a value to compare the attribute against. To test that a boolean value is true, use the !! operator (or -true if !! seems a little too weird for your taste):

    my $entries = $kdbx->entries->where('!!'  => 'quality_check');
    my $entries = $kdbx->entries->where(-true => 'quality_check');  # same thing

Yes, there is also a -false and a -not if you prefer one of those over !. -false and -not (along with -true) are also special in that you can use them to invert the logic of a subquery. These are logically equivalent:

    my $entries = $kdbx->entries->where(-not => { title => 'My Bank' });
    my $entries = $kdbx->entries->where(title => { 'ne' => 'My Bank' });

These special operators become more useful when combined with two more special operators: -and and -or. With these, it is possible to construct more interesting queries with groups of logic. For example:

    my $entries = $kdbx->entries->where({
        title   => { '=~', qr/bank/ },
        -not    => {
            -or     => {
                notes   => { '=~', qr/business/ },
                icon_id => { '==', ICON_TRASHCAN_FULL },

In English, find entries where the word "bank" appears anywhere in the title but also do not have either the word "business" in the notes or are using the full trashcan icon.

Subroutine Query

Lastly, as mentioned at the top, you can ignore all this and write your own subroutine. Your subroutine will be called once for each object being searched over. The subroutine should match the candidate against whatever criteria you want and return true if it matches or false to skip. To do this, just pass your subroutine coderef to where.

To review the different types of queries, these are all equivalent to find all entries in the database titled "My Bank":

    my $entries = $kdbx->entries->where(\'"My Bank"', 'eq', qw[title]);     # simple expression
    my $entries = $kdbx->entries->where(title => 'My Bank');                # declarative syntax
    my $entries = $kdbx->entries->where(sub { $_->title eq 'My Bank' });    # subroutine query

This is a trivial example, but of course your subroutine can be arbitrarily complex.

All of these query mechanisms described in this section are just tools, each with its own set of limitations. If the tools are getting in your way, you can of course iterate over the contents of a database and implement your own query logic, like this:

    my $entries = $kdbx->entries;
    while (my $entry = $entries->next) {
        if (wanted($entry)) {
        else {


Iterators are the built-in way to navigate or walk the database tree. You get an iterator from "entries", "groups" and "objects". You can specify the search algorithm to iterate over objects in different orders using the algorithm option, which can be one of these constants:

  • ITERATION_IDS - Iterative deepening search (default)

  • ITERATION_DFS - Depth-first search

  • ITERATION_BFS - Breadth-first search

When iterating over objects generically, groups always precede their direct entries (if any). When the history option is used, current entries always precede historical entries.

If you have a database tree like this:

    - Root
        - Group1
            - EntryA
            - Group2
                - EntryB
        - Group3
            - EntryC
  • IDS order of groups is: Root, Group1, Group2, Group3

  • IDS order of entries is: EntryA, EntryB, EntryC

  • IDS order of objects is: Root, Group1, EntryA, Group2, EntryB, Group3, EntryC

  • DFS order of groups is: Group2, Group1, Group3, Root

  • DFS order of entries is: EntryB, EntryA, EntryC

  • DFS order of objects is: Group2, EntryB, Group1, EntryA, Group3, EntryC, Root

  • BFS order of groups is: Root, Group1, Group3, Group2

  • BFS order of entries is: EntryA, EntryC, EntryB

  • BFS order of objects is: Root, Group1, EntryA, Group3, EntryC, Group2, EntryB


TODO - This is a planned feature, not yet implemented.


Errors in this package are constructed as File::KDBX::Error objects and propagated using perl's built-in mechanisms. Fatal errors are propagated using "die LIST" in perlfunc and non-fatal errors (a.k.a. warnings) are propagated using "warn LIST" in perlfunc while adhering to perl's warnings system. If you're already familiar with these mechanisms, you can skip this section.

You can catch fatal errors using "eval BLOCK" in perlfunc (or something like Try::Tiny) and non-fatal errors using $SIG{__WARN__} (see "%SIG" in perlvar). Examples:

    use File::KDBX::Error qw(error);

    my $key = '';   # uh oh
    eval {
        $kdbx->load_file('whatever.kdbx', $key);
    if (my $error = error($@)) {
        handle_missing_key($error) if $error->type eq 'key.missing';

or using Try::Tiny:

    try {
        $kdbx->load_file('whatever.kdbx', $key);
    catch {

Catching non-fatal errors:

    my @warnings;
    local $SIG{__WARN__} = sub { push @warnings, $_[0] };

    $kdbx->load_file('whatever.kdbx', $key);

    handle_warnings(@warnings) if @warnings;

By default perl prints warnings to STDERR if you don't catch them. If you don't want to catch them and also don't want them printed to STDERR, you can suppress them lexically (perl v5.28 or higher required):

        no warnings 'File::KDBX';

or locally:

        local $File::KDBX::WARNINGS = 0;

or globally in your program:

    $File::KDBX::WARNINGS = 0;

You cannot suppress fatal errors, and if you don't catch them your program will exit.


This software will alter its behavior depending on the value of certain environment variables:

  • PERL_FILE_KDBX_XS - Do not use File::KDBX::XS if false (default: true)

  • PERL_ONLY - Do not use File::KDBX::XS if true (default: false)

  • NO_FORK - Do not fork if true (default: false)


  • KeePass Password Safe - The original KeePass

  • KeePassXC - Cross-Platform Password Manager written in C++

  • File::KeePass has overlapping functionality. It's good but has a backlog of some pretty critical bugs and lacks support for newer KDBX features.


Please report any bugs or feature requests on the bugtracker website

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.


Charles McGarvey <>


This software is copyright (c) 2022 by Charles McGarvey.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.