KEYCTL\_PKEY\_QUERY(3) Linux Key Management Calls KEYCTL\_PKEY\_QUERY(3)

# [NAME](#NAME)

keyctl\_pkey\_query - Query public key parameters

# [SYNOPSIS](#SYNOPSIS)

```
#include <keyutils.h>

long keyctl_pkey_query(key_serial_t key, const char *info,
                       struct keyctl_pkey_query *result);
```

# [DESCRIPTION](#DESCRIPTION)

**keyctl\_pkey\_query**() queries the public key parameters associated with a kernel key that supports these operations (typically **asymmetric**-type). The caller must have **search** permission on the target key to be able to query its parameters.

When invoking the function, *key* indicates the key to be queried, *info* points to a space- or tab-separated string of "key\[=value]" parameters and *result* points to a buffer in which the result will be placed.

The parameters that can be used in the *info* parameter string are dependent on the type of key. Parameters can specify such things as encoding types (such as "enc=pkcs1"); see [asymmetric-key(7)](/man/os/keyutils/asymmetric-key.7) for more information.

If successful, the result is written into the following struct:

```
struct keyctl_pkey_query {


        unsigned int    supported_ops;


        unsigned int    key_size;


        unsigned short  max_data_size;


        unsigned short  max_sig_size;


        unsigned short  max_enc_size;


        unsigned short  max_dec_size;
};
```

The *supported\_ops* field contains a bitmask of the following constants:

**KEYCTL\_SUPPORTS\_ENCRYPT** **KEYCTL\_SUPPORTS\_DECRYPT** **KEYCTL\_SUPPORTS\_SIGN** **KEYCTL\_SUPPORTS\_VERIFY**

indicating what operations are supported and thus which of the other **keyctl\_pkey\_\***() operations can be used with this key.

The *key\_size* field indicates the number of bits in the key size and the *max\_data\_size*, *max\_sig\_size*, *max\_enc\_size* and *max\_dec\_size* fields indicate the maximum sizes in bytes of a blob of data to be signed, a signature blob, a blob to be encrypted and a blob to be decrypted respectively.

# [RETURN VALUE](#RETURN_VALUE)

On success **keyctl\_pkey\_query**() returns **0**. On error, the value **-1** will be returned and *errno* will have been set to an appropriate error.

# [ERRORS](#ERRORS)

[**ENOKEY**](#ENOKEY)

The key specified is invalid.

[**EKEYEXPIRED**](#EKEYEXPIRED)

The key specified has expired.

[**EKEYREVOKED**](#EKEYREVOKED)

The key specified has been revoked.

[**EACCES**](#EACCES)

The key exists, but is not **searchable** by the calling process.

[**ENOPKG**](#ENOPKG)

Some facility needed to complete the requested operation is not available. This is most probably a requested or required digest or encryption algorithm.

[**EFAULT**](#EFAULT)

Bad address.

# [LINKING](#LINKING)

This is a library function that can be found in *libkeyutils*. When linking, **-lkeyutils** should be specified to the linker.

# [SEE ALSO](#SEE_ALSO)

[**keyctl**(1)](/man/os/keyutils/keyctl.1), [**add\_key**(2)](/man/os/keyutils/add_key.2), [**keyctl**(2)](/man/os/keyutils/keyctl.2), [**keyctl**(3)](/man/os/keyutils/keyctl.3), [**keyctl\_pkey\_encrypt**(3)](/man/os/keyutils/keyctl_pkey_encrypt.3), [**keyctl\_pkey\_sign**(3)](/man/os/keyutils/keyctl_pkey_sign.3), [**asymmetric-key**(7)](/man/os/keyutils/asymmetric-key.7), [**keyrings**(7)](/man/os/keyutils/keyrings.7), [**keyutils**(7)](/man/os/keyutils/keyutils.7)

8 Nov 2018 Linux

---

Document: keyctl_pkey_query(3) from keyutils 1.6.3-r41 (Chainguard OS)
Source: https://kernel.googlesource.com/pub/scm/linux/kernel/git/dhowells/keyutils.git