--- name: "tcplay" section: "3" platform: "linux" package: "tcplay" version: "3.3-4" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/tcplay/3" --- # tcplay(3) TrueCrypt volume management ## NAME **tc\_api\_init**, **tc\_api\_uninit**, **tc\_api\_has**, **tc\_api\_cipher\_iterate**, **tc\_api\_prf\_iterate**, **tc\_api\_task\_init**, **tc\_api\_task\_uninit**, **tc\_api\_task\_set**, **tc\_api\_task\_do**, **tc\_api\_task\_info\_get**, **tc\_api\_task\_get\_error** – TrueCrypt volume management ## LIBRARY library “libtcplay” ## SYNOPSIS **#include \** *typedef* *int*\ **(\*tc\_api\_cipher\_iterator\_fn)**(*void \*priv*, *const char \*name*, *int key\_length\_in\_bits*, *int ciphers\_in\_chain*); *typedef* *int*\ **(\*tc\_api\_prf\_iterator\_fn)**(*void \*priv*, *const char \*name*); *typedef* *int*\ **(\*tc\_api\_state\_change\_fn)**(*void \*priv*, *const char \*state*, *int enter\_state*); *int*\ **tc\_api\_init**(*int verbose*); *int*\ **tc\_api\_uninit**(*void*); *int*\ **tc\_api\_has**(*const char \*feature*); *int*\ **tc\_api\_cipher\_iterate**(*tc\_api\_cipher\_iterator\_fn fn*, *void \*priv*); *int*\ **tc\_api\_prf\_iterate**(*tc\_api\_prf\_iterator\_fn fn*, *void \*priv*); *tc\_api\_task*\ **tc\_api\_task\_init**(*const char \*op*); *int*\ **tc\_api\_task\_uninit**(*tc\_api\_task task*); *int*\ **tc\_api\_task\_set**(*tc\_api\_task task*, *const char \*key*, *...*); *int*\ **tc\_api\_task\_do**(*tc\_api\_task task*); *int*\ **tc\_api\_task\_info\_get**(*tc\_api\_task task*, *const char \*key*, *...*); *const* *char* *\**\ **tc\_api\_task\_get\_error**(*tc\_api\_task task*); ## DESCRIPTION The **tcplay** library provides an interface to create, query, map and manage TrueCrypt-compatible volumes. The **tc\_api\_init**() function initializes the library internals and prepares it for use via the API. This function has to be called before using any other API function. If the *verbose* argument is non-zero, then the library will output information such as errors via stdout and stderr. The **tc\_api\_uninit**() function clears up all internal secure memory, such as memory used for decrypted headers, passphrases, keyfiles, etc. The **tc\_api\_has**() function checks whether the loaded tcplay library has the feature specified by the *feature* argument. The current version of the **tcplay** library supports the following features: | | | | --- | --- | | **Feature** | **Description** | | trim | Allows enabling discards/TRIM when mapping a volume | The **tc\_api\_cipher\_iterate**() function passes every available cipher chain to the callback provided in the *fn* argument. The *priv* argument is passed on every call of the callback function. The name of the cipher chain is passed to the callback function in the *name* argument. Similarly, the *ciphers\_in\_chain* argument holds the number of ciphers in the current chain, and *key\_length\_in\_bits* holds the total key length for the cipher chain, in bits. The **tc\_api\_prf\_iterate**() function passes every available cipher chain to the callback provided in the *fn* argument. The *priv* argument is passed on every call of the callback function. The name of the PKBDF2 PRF algorithm is passed to the callback function in the *name* argument. The **tc\_api\_task\_init**() function initializes and returns a *tc\_api\_task* opaque pointer that can be used to run **tcplay** commands. Each task can be used only for a single **tc\_api\_task\_do**() call, and must be deallocated using **tc\_api\_task\_uninit**(). The *op* argument can be one of the following: - **create** Create a new encrypted TrueCrypt volume. - **map** Map an existing TrueCrypt volume. - **info** Request information about an encrypted TrueCrypt volume. - **info\_mapped** Request information about a mapped TrueCrypt volume. - **unmap** Unmap a mapped TrueCrypt volume. - **modify** Modify the TrueCrypt volume by changing the passphrase, keyfiles, PRF algorithm, restoring from a backup header, restoring from a header file or saving to a header file. - **restore** Modify the TrueCrypt volume as **modify** does, but without changing the passphrase, keyfiles or PRF algorithm. The **tc\_api\_task\_set**() function allows settting a number of different options for the current task. The following table shows which keys are available on calls to **tc\_api\_task\_set**() for each of the operations. The letter **M** indicates the setting is mandatory, whilst **\*** indicates the setting is optional. | | | | | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | | **Key** | **create** | **info** | **map** | **unmap** | **info\_mapped** | **modify** | **restore** | | dev | M | M | M | \* | | M | M | | map\_name | | | M | M | M | | | | interactive | \* | \* | \* | | | \* | \* | | retries | \* | \* | \* | | | \* | \* | | timeout | \* | \* | \* | | | | | | state\_change\_fn | \* | | | | | \* | \* | | weak\_keys\_and\_salt | \* | | | | | \* | \* | | secure\_erase | \* | | | | | | | | hidden\_size\_bytes | \* | | | | | | | | prf\_algo | \* | | | | | | | | h\_prf\_algo | \* | | | | | | | | cipher\_chain | \* | | | | | | | | h\_cipher\_chain | \* | | | | | | | | protect\_hidden | | \* | \* | | | | | | fde | | \* | \* | | | | | | sys | | \* | \* | | | ? | ? | | use\_backup\_header | | \* | \* | | | \* | \* | | header\_from\_file | | \* | \* | | | \* | \* | | hidden\_header\_from\_file | | \* | \* | | | \* | \* | | allow\_trim | | | \* | | | | | | save\_header\_to\_file | | | | | | \* | | | passphrase | \* | \* | \* | | | \* | \* | | h\_passphrase | \* | \* | \* | | | \* | \* | | keyfiles | \* | \* | \* | | | \* | \* | | h\_keyfiles | \* | \* | \* | | | \* | \* | | new\_passphrase | | | | | | \* | | | new\_keyfiles | | | | | | \* | | | new\_prf\_algo | | | | | | \* | | The varargs accepted by the **tc\_api\_task\_set**() function depend on the key being set. - dev The vararg is of type *const* *char* *\**. It sets the device that contains the TrueCrypt volume to operate on. - map\_name The vararg is of type *const* *char* *\**. It set the name of the mapped volume. - interactive The vararg is of type *int*. It determines whether the user will be prompted for a passphrase or whether the settings are taken from the arguments set using **tc\_api\_task\_set**(). - retries The vararg is of type *int*. It determines the number of passphrase retries if *interactive* is set. - weak\_keys\_and\_salt The vararg is of type *int*. It determines whether to use a weak source of entropy for key material and/or the salt. - secure\_erase The vararg is of type *int*. It determines whether a secure erase is performed as part of the volume creation. - hidden\_size\_bytes The vararg is of type *int64\_t*. If set to *0* it implies no hidden volume will be created. A positive value implies a hidden volume of the specified size in bytes is created. - prf\_algo The vararg is of type *const* *char* *\** and must be a valid PBKDF2 PRF algorithm. It determines which PBKDF2 PRF algorithm is used for the outer volume. - h\_prf\_algo The vararg is of type *const* *char* *\** and must be a valid PBKDF2 PRF algorithm. It determines which PBKDF2 PRF algorithm is used for the hidden volume. - cipher\_chain The vararg is of type *const* *char* *\** and must be a valid **tcplay** cipher chain. It determines which cipher chain is used to encrypt the outer volume. - h\_cipher\_chain The vararg is of type *const* *char* *\** and must be a valid **tcplay** cipher chain. It determines which cipher chain is used to encrypt the hidden volume. - protect\_hidden The vararg is of type *int*. It determines whether the size of the outer volume should be adjusted to protect any hidden volume. Using this mode requires both outer and hidden passphrases and keyfiles. - sys The vararg is of type *const* *char* *\**. It determines whether the volume is a system encrypted volume, and if so, which disk is the system disk and hence contains the header. If set to NULL the volume will implicitly be treated as a non-system encrypted volume. - fde The vararg is of type *int*. It determines whether the disk uses full disk encryption or not. If specified, the device pointed to by the *dev* setting should be a whole disk device, not any partition. The device will be mapped or queried as a whole. To access individual partitions, a utility such as [kpartx(8)](/kpartx/8.md) should be used, which will create additional individual mappings for each partition in the decrypted mapped volume. For more details on full disk encryption, see [tcplay(8)](/tcplay/8.md). - use\_backup\_header The vararg is of type *int*. It determines whether the backup header should be used instead of the regular header to access the volume. - header\_from\_file The vararg is of type *const* *char* *\**. If not NULL it forces **tcplay** to use the header in the specified file instead of the regular outer volume header. - hidden\_header\_from\_file The vararg is of type *const* *char* *\**. If not NULL it forces **tcplay** to use the header in the specified file instead of the regular hidden volume header. - allow\_trim The vararg is of type *int*. It specifies whether the mapped volume should allow discards (TRIM). - save\_header\_to\_file The vararg is of type *const* *char* *\**. If not NULL it forces **tcplay** to write the (modified) header to the specified file instead of replacing the volume headers. - passphrase The vararg is of type *const* *char* *\**. It sets the passphrase that **tcplay** uses to access the volume. - h\_passphrase The vararg is of type *const* *char* *\**. It sets the passphrase that **tcplay** uses to unlock the hidden volume header. This option is only used if a hidden volume is being created or the *protect\_hidden* setting is set. Otherwise **tcplay** will first use the regular passphrase to try to unlock the outer volume and then try to unlock the hidden volume header with the same passphrase without ever using *h\_passphrase*. - keyfiles The vararg is of type *const* *char* *\**. If not NULL the given keyfile will be added to the keyfile pool. Multiple calls to set this option with a non- NULL argument result add additional keyfiles. If NULL all keyfiles are cleared. - h\_keyfiles The vararg is of type *const* *char* *\**. If not NULL the given keyfile will be added to the keyfile pool. Multiple calls to set this option with a non- NULL argument result add additional keyfiles. If NULL all keyfiles are cleared. This option is only used if a hidden volume is being created or the *protect\_hidden* setting is set. Otherwise **tcplay** will first use the regular keyfiles to try to unlock the outer volume and then try to unlock the hidden volume header with the same keyfiles without ever using *h\_keyfiles*. - new\_passphrase The vararg is of type *const*, *char*, *\**. It specifies the new passphrase to use when modifying the volume header. - new\_keyfiles The vararg is of type *const*, *char*, *\**. If not NULL the given keyfile will be added to the new keyfile pool. Multiple calls to set this option with a non- NULL argument result add additional keyfiles. If NULL all new keyfiles are cleared. When the volume header is modified, it will be reencrypted using the new keyfiles. - new\_prf\_algo The vararg is of type *const* *char* *\** and must be a valid PBKDF2 PRF algorithm. It determines which PBKDF2 PRF algorithm is used when reencrypting the (modified) volume header. - state\_change\_fn The first vararg is of type *tc\_api\_state\_change\_fn* and the second vararg is of type *void*, *\**. It allows the consumer to provide a callback function which will be called when starting and stopping a time-intensive sub-operation such as collecting entropy or erasing a volume. The second vararg is passed as the *priv* argument to the callback. The *enter\_state* argument to the callback determines whether **tcplay** is starting or stopping the time-intensive sub-task specified in the *state* argument. The **tc\_api\_task\_do**() function runs the task specified in the *task* argument. Before running the task, **tc\_api\_task\_do**() performs a simple sanity check of the arguments set previously using **tc\_api\_task\_set**() before performing the actual operation. After a call to **tc\_api\_task\_do**() for the **info** or **info\_mapped** operations, the queried information is available to be accessed using **tc\_api\_task\_info\_get**(). The **tc\_api\_task\_info\_get**() function can be used to query the result of a **info** or **info\_mapped** operation. The *task* argument is the task used in a previous **tc\_api\_task\_do**() call. The *key* argument can be one of the following: | | | | | --- | --- | --- | | **Key** | **type** | **Description** | | device | *char* *\** | Corresponding device node | | cipher | *char* *\** | Used cipher chain | | prf | *char* *\** | Used PBKDF2 PRF algorithm | | key\_bits | *int* *\** | Number of key bits | | size | *int64\_t* *\** | Volume size in bytes | | iv\_offset | *int64\_t* *\** | IV Offset of volume in bytes | | block\_offset | *int64\_t* *\** | Block Offset of volume in bytes | The second vararg argument must be of the type specified in the above table. The first vararg argument is always the size of the storage provided in the second argument. For a *char* *\** argument, the size corresponds to the size of the buffer at the provided location and must be of type *size\_t*. For an *int* *\** or *int64\_t* *\** argument, it should be the size of the underlying type. The **tc\_api\_task\_get\_error**() function can be used to get a detailed error message after a failed *tc\_api\_task\_do* call. The *task* argument is the task used in a previous **tc\_api\_task\_do**() call. ## NOTES TrueCrypt limits passphrases to 64 characters (including the terminating null character). To be compatible with it, **tcplay** does the same. All passphrases (exlcuding keyfiles) are trimmed to 64 characters. Similarly, keyfiles are limited to a size of 1 MB, but up to 256 keyfiles can be used. ## RETURN VALUES All functions except **tc\_api\_task\_init**() and **tc\_api\_task\_get\_error**() return either TC\_OK to indicate that the operation completed successfully, or TC\_ERR\_UNIMPL to indicate that the operation is not implemented , or TC\_ERR to indicate that any other error occured. The **tc\_api\_task\_get\_error**() function always return a valid, but possibly empty (or irrelevant, if not called after an error occurred) string. The **tc\_api\_task\_init**() function returns NULL if an error occurred and an opaque *tc\_api\_task* otherwise. ## COMPATIBILITY The **tcplay** library offers full compatibility with TrueCrypt volumes including hidden volumes, system encryption (map-only), keyfiles and cipher cascading. ## SEE ALSO [tcplay(8)](/tcplay/8.md), [kpartx(8)](/kpartx/8.md) ## HISTORY The **tcplay** library appeared in DragonFly 2.11. ## AUTHORS Alex Hornung