> For the complete documentation index, see [llms.txt](https://developer.magtek.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.magtek.com/api-and-command-reference/dynafamily-programmers-manual/commands/0xennn-security/0xef11-get-key-info.md).

# 0xEF11 - Get Key Info

The host uses this command to retrieve information about a key slot, including details about the key stored in that slot. It can be used for several purposes, including:

* Determine if a key exists / has been loaded
* Get key derivation data to derive a DUKPT key
* Get transport key information to retrieve the appropriate transport key

Sequence of events:

{% stepper %}
{% step %}

### Construct request

The host constructs the command request in the format below.
{% endstep %}

{% step %}

### Send request

The host sends the command request to the device.
{% endstep %}

{% step %}

### Receive response

The device sends a response in the format below to the host.
{% endstep %}
{% endstepper %}

## Request Data for Command 0xEF11 - Get Key Info

<table><thead><tr><th width="235">Tag</th><th width="73.33331298828125" align="right">Len</th><th>Value / Description</th><th width="74.3333740234375">Typ</th><th width="74.99993896484375">Req</th><th width="99.333251953125">Default</th></tr></thead><tbody><tr><td>Beginning of any wrappers, at minimum including <strong>Request Message</strong> </td><td align="right"></td><td></td><td></td><td></td><td></td></tr><tr><td>EF11</td><td align="right"></td><td><a href="https://developer.magtek.com/api-and-command-reference/dynafamily-programmers-manual/commands/0xennn-security/0xef11-get-key-info"><mark style="color:red;"><strong>Command 0xEF11 - Get Key Info</strong></mark></a></td><td></td><td></td><td></td></tr><tr><td>81</td><td align="right">02</td><td><a href="https://developer.magtek.com/api-and-command-reference/dynafamily-programmers-manual/data-types-and-shared-tlv-data-objects/tr-31-key-block-type"><mark style="color:red;"><strong>Key Slot ID</strong></mark></a> </td><td>B</td><td>R</td><td></td></tr><tr><td>End of any wrappers, at minimum including <strong>Request Message</strong> </td><td align="right"></td><td></td><td></td><td></td><td></td></tr></tbody></table>

## Response Data for Command 0xEF11 - Get Key Info

<table><thead><tr><th>Tag</th><th width="73.6666259765625" align="right">Len</th><th>Value / Description</th><th width="78.3333740234375">Typ</th><th width="75.99993896484375">Req</th><th width="90.666748046875">Default</th></tr></thead><tbody><tr><td>EF11 = <strong>Get Key Info - Command 0xEF11</strong> </td><td align="right"></td><td></td><td></td><td></td><td></td></tr><tr><td>81</td><td align="right">04</td><td>Key Slot Information</td><td>B</td><td>R</td><td></td></tr><tr><td>82</td><td align="right">06</td><td>Loaded Key Information</td><td>B</td><td>O</td><td></td></tr><tr><td>/null</td><td align="right">(1)</td><td><p>Key Slot Status</p><p>·       0x00 = Empty</p><p>·       0x01 = Loaded (Key not assigned purpose)</p><p>·       0x02 = Loaded &#x26; Active</p><p>·       0x03 = Exhausted (End of DUKPT key sequence</p><p>·       0x04 = Expired (Reserved, certificate status)</p><p>0xFF = Not supported in this device</p></td><td>B</td><td>R</td><td></td></tr><tr><td>/null</td><td align="right">(1)</td><td><p>Key Slot Type</p><p>First byte of the <a href="https://developer.magtek.com/api-and-command-reference/dynafamily-programmers-manual/data-types-and-shared-tlv-data-objects/tr-31-key-block-type#key-slot-ids-a"><mark style="color:red;"><strong>Key Slot ID</strong></mark></a> in the host’s request message.</p></td><td>B</td><td>R</td><td></td></tr><tr><td>/null</td><td align="right">(2)</td><td><p>Transport <a href="https://developer.magtek.com/api-and-command-reference/dynafamily-programmers-manual/data-types-and-shared-tlv-data-objects/tr-31-key-block-type#key-slot-ids-a"><mark style="color:red;"><strong>Key Slot ID</strong></mark></a></p><p>This specifies the key used to secure and load the key that the host is retrieving information about. See <a href="https://developer.magtek.com/api-and-command-reference/dynafamily-programmers-manual/data-types-and-shared-tlv-data-objects/tr-31-key-block-type#key-slot-ids-a"><mark style="color:red;"><strong>Key Slot ID</strong></mark></a></p></td><td>B</td><td>R</td><td></td></tr><tr><td>82</td><td align="right">06</td><td>Loaded Key Information</td><td>B</td><td>O</td><td></td></tr><tr><td>/null</td><td align="right">(1)</td><td>Key Environment — ‘T’ = Test, ‘P’ = Production</td><td>A</td><td>R</td><td></td></tr><tr><td>/null</td><td align="right">(4)</td><td>TR-31 Attributes — See <a href="https://developer.magtek.com/api-and-command-reference/dynafamily-programmers-manual/data-types-and-shared-tlv-data-objects/tr-31-key-block-type#magtek-custom-key-data-fields"><mark style="color:red;"><strong>TR-31 Key Type Table - Usage/Algorithm/Mode.</strong></mark></a></td><td>B</td><td>R</td><td></td></tr><tr><td>/null</td><td align="right">(1)</td><td>Encoding of Algorithm &#x26; Length:<br>- 0x01 = DEA<br>- 0x02 = 2TDEA<br>- 0x03 = 3TDEA<br>- 0x04 = AES128<br>- 0x05 = AES192<br>- 0x06 = AES256</td><td>B</td><td>R</td><td></td></tr><tr><td>83</td><td align="right">var</td><td>Key Check Value:<br>- For AES-CMAC, 5 bytes.<br>- For TDES-CMAC or TDES-CBCMAC, 3 bytes.</td><td>B</td><td>O</td><td></td></tr><tr><td>84</td><td align="right">var</td><td>Key Derivation Information — Contains the derivation block, key serial number (KSN), or key label, as appropriate for the key type.</td><td>B</td><td>O</td><td></td></tr><tr><td>A6</td><td align="right">var</td><td>Restrictions — Reserved. Do not include.</td><td>B</td><td>O</td><td></td></tr><tr><td>81</td><td align="right">02</td><td>DUKPT Restrictions — These restrictions come from the TR-31 block.</td><td>B</td><td>O</td><td></td></tr><tr><td>89</td><td align="right">var</td><td>Timestamp — This comes from the TR-31 block or from device’s real-time clock.</td><td>B</td><td>O</td><td></td></tr></tbody></table>

#### Request Example&#x20;

{% code title="Example (hex)" %}

```
AA 00 81 04 01 21 EF 11 84 06 EF 11 81 02 20 07
```

{% endcode %}

#### Response Example

{% code title="Example (hex)" %}

```
AA 00 81 04 82 21 EF 11 82 04 00 00 00 00 84 34 A2 32 81 04 02 20 10 81 82 06 54 
42 31 54 58 03 84 0A FF FF 98 76 54 32 10 30 00 00 A6 04 81 02 00 3F 89 10 32 30 
32 30 30 39 30 32 54 31 35 35 38 30 32 5A
```

{% endcode %}


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