# Importing a Key in Plaintext (ArkTS)


This topic walks you through on how to import an AES 256-bit key and an RSA 2048-bit key. For details about the scenarios and supported algorithm specifications, see [Supported Algorithms](huks-key-import-overview.md#supported-algorithms).


## How to Develop

1. Set the alias **keyAlias** of the key to import.
   The key alias cannot exceed 128 bytes.

2. Encapsulate the key property set and key material.
   - The key property set must contain [HuksKeyAlg](../../reference/apis-universal-keystore-kit/js-apis-huks.md#hukskeyalg), [HuksKeySize](../../reference/apis-universal-keystore-kit/js-apis-huks.md#hukskeysize), and [HuksKeyPurpose](../../reference/apis-universal-keystore-kit/js-apis-huks.md#hukskeypurpose).
   - The key material must comply with the [HUKS key material format](huks-concepts.md#key-material-format) and is used to fill the **inData** field of [HuksOptions](../../reference/apis-universal-keystore-kit/js-apis-huks.md#huksoptions) in Uint8Array format.

3. Use [huks.importKeyItem](../../reference/apis-universal-keystore-kit/js-apis-huks.md#huksimportkeyitem9) to import the key.

```ts
/* Import an AES 256-bit key in plaintext. This example uses callback-based APIs. */
import { huks } from '@kit.UniversalKeystoreKit'

/* Key material */
let plainTextSize32 = new Uint8Array([
  0xfb, 0x8b, 0x9f, 0x12, 0xa0, 0x83, 0x19, 0xbe, 0x6a, 0x6f, 0x63, 0x2a, 0x7c, 0x86, 0xba, 0xca,
  0x64, 0x0b, 0x88, 0x96, 0xe2, 0xfa, 0x77, 0xbc, 0x71, 0xe3, 0x0f, 0x0f, 0x9e, 0x3c, 0xe5, 0xf9
]);
/* 1. Set the key alias. */
let keyAlias = 'AES256Alias_sample';
/* 2. Encapsulate the key property set and key material. */

let properties: Array<huks.HuksParam> = [
  {
    tag: huks.HuksTag.HUKS_TAG_ALGORITHM,
    value: huks.HuksKeyAlg.HUKS_ALG_AES
  },
  {
    tag: huks.HuksTag.HUKS_TAG_KEY_SIZE,
    value: huks.HuksKeySize.HUKS_AES_KEY_SIZE_256
  },
  {
    tag: huks.HuksTag.HUKS_TAG_PURPOSE,
    value: huks.HuksKeyPurpose.HUKS_KEY_PURPOSE_ENCRYPT | huks.HuksKeyPurpose.HUKS_KEY_PURPOSE_DECRYPT
  },
]
let options: huks.HuksOptions = {
  properties: properties,
  inData: plainTextSize32
};
/* 3. Import the key in plaintext. */
try {
  huks.importKeyItem(keyAlias, options, (error, data) => {
    if (error) {
      console.error(`callback: importKeyItem failed` + JSON.stringify(error));
    } else {
      console.info(`callback: importKeyItem success`);
    }
  });
} catch (error) {
  console.error(`callback: importKeyItem input arg invalid` + JSON.stringify(error));
}
```

```ts
/* Import an RSA 2048-bit key in plaintext. This example uses callback-based APIs. */
import { huks } from '@kit.UniversalKeystoreKit'

let rsa2048KeyPairMaterial = new Uint8Array([
  0x01, 0x00, 0x00, 0x00, // Key algorithm (expressed in little-endian) huks.HuksKeyAlg.HUKS_ALG_RSA = 1
  0x00, 0x08, 0x00, 0x00, // Key size (bit): 2048
  0x00, 0x01, 0x00, 0x00, // Length of modulus n (byte): 256
  0x03, 0x00, 0x00, 0x00, // Length of the public key exponent e (byte): 3
  0x00, 0x01, 0x00, 0x00, // Length of the private key exponent d (byte): 256
  // Modulus n
  0xc5, 0x35, 0x62, 0x48, 0xc4, 0x92, 0x87, 0x73, 0x0d, 0x42, 0x96, 0xfc, 0x7b, 0x11, 0x05, 0x06,
  0x0f, 0x8d, 0x66, 0xc1, 0x0e, 0xad, 0x37, 0x44, 0x92, 0x95, 0x2f, 0x6a, 0x55, 0xba, 0xec, 0x1d,
  0x54, 0x62, 0x0a, 0x4b, 0xd3, 0xc7, 0x05, 0xe4, 0x07, 0x40, 0xd9, 0xb7, 0xc2, 0x12, 0xcb, 0x9a,
  0x90, 0xad, 0xe3, 0x24, 0xe8, 0x5e, 0xa6, 0xf8, 0xd0, 0x6e, 0xbc, 0xd1, 0x69, 0x7f, 0x6b, 0xe4,
  0x2b, 0x4e, 0x1a, 0x65, 0xbb, 0x73, 0x88, 0x6b, 0x7c, 0xaf, 0x7e, 0xd0, 0x47, 0x26, 0xeb, 0xa5,
  0xbe, 0xd6, 0xe8, 0xee, 0x9c, 0xa5, 0x66, 0xa5, 0xc9, 0xd3, 0x25, 0x13, 0xc4, 0x0e, 0x6c, 0xab,
  0x50, 0xb6, 0x50, 0xc9, 0xce, 0x8f, 0x0a, 0x0b, 0xc6, 0x28, 0x69, 0xe9, 0x83, 0x69, 0xde, 0x42,
  0x56, 0x79, 0x7f, 0xde, 0x86, 0x24, 0xca, 0xfc, 0xaa, 0xc0, 0xf3, 0xf3, 0x7f, 0x92, 0x8e, 0x8a,
  0x12, 0x52, 0xfe, 0x50, 0xb1, 0x5e, 0x8c, 0x01, 0xce, 0xfc, 0x7e, 0xf2, 0x4f, 0x5f, 0x03, 0xfe,
  0xa7, 0xcd, 0xa1, 0xfc, 0x94, 0x52, 0x00, 0x8b, 0x9b, 0x7f, 0x09, 0xab, 0xa8, 0xa4, 0xf5, 0xb4,
  0xa5, 0xaa, 0xfc, 0x72, 0xeb, 0x17, 0x40, 0xa9, 0xee, 0xbe, 0x8f, 0xc2, 0xd1, 0x80, 0xc2, 0x0d,
  0x44, 0xa9, 0x59, 0x44, 0x59, 0x81, 0x3b, 0x5d, 0x4a, 0xde, 0xfb, 0xae, 0x24, 0xfc, 0xa3, 0xd9,
  0xbc, 0x57, 0x55, 0xc2, 0x26, 0xbc, 0x19, 0xa7, 0x9a, 0xc5, 0x59, 0xa3, 0xee, 0x5a, 0xef, 0x41,
  0x80, 0x7d, 0xf8, 0x5e, 0xc1, 0x1d, 0x32, 0x38, 0x41, 0x5b, 0xb6, 0x92, 0xb8, 0xb7, 0x03, 0x0d,
  0x3e, 0x59, 0x0f, 0x1c, 0xb3, 0xe1, 0x2a, 0x95, 0x1a, 0x3b, 0x50, 0x4f, 0xc4, 0x1d, 0xcf, 0x73,
  0x7c, 0x14, 0xca, 0xe3, 0x0b, 0xa7, 0xc7, 0x1a, 0x41, 0x4a, 0xee, 0xbe, 0x1f, 0x43, 0xdd, 0xf9,
  // Public key exponent e
  0x01, 0x00, 0x01,
  // Private key exponent d
  0x88, 0x4b, 0x82, 0xe7, 0xe3, 0xe3, 0x99, 0x75, 0x6c, 0x9e, 0xaf, 0x17, 0x44, 0x3e, 0xd9, 0x07,
  0xfd, 0x4b, 0xae, 0xce, 0x92, 0xc4, 0x28, 0x44, 0x5e, 0x42, 0x79, 0x08, 0xb6, 0xc3, 0x7f, 0x58,
  0x2d, 0xef, 0xac, 0x4a, 0x07, 0xcd, 0xaf, 0x46, 0x8f, 0xb4, 0xc4, 0x43, 0xf9, 0xff, 0x5f, 0x74,
  0x2d, 0xb5, 0xe0, 0x1c, 0xab, 0xf4, 0x6e, 0xd5, 0xdb, 0xc8, 0x0c, 0xfb, 0x76, 0x3c, 0x38, 0x66,
  0xf3, 0x7f, 0x01, 0x43, 0x7a, 0x30, 0x39, 0x02, 0x80, 0xa4, 0x11, 0xb3, 0x04, 0xd9, 0xe3, 0x57,
  0x23, 0xf4, 0x07, 0xfc, 0x91, 0x8a, 0xc6, 0xcc, 0xa2, 0x16, 0x29, 0xb3, 0xe5, 0x76, 0x4a, 0xa8,
  0x84, 0x19, 0xdc, 0xef, 0xfc, 0xb0, 0x63, 0x33, 0x0b, 0xfa, 0xf6, 0x68, 0x0b, 0x08, 0xea, 0x31,
  0x52, 0xee, 0x99, 0xef, 0x43, 0x2a, 0xbe, 0x97, 0xad, 0xb3, 0xb9, 0x66, 0x7a, 0xae, 0xe1, 0x8f,
  0x57, 0x86, 0xe5, 0xfe, 0x14, 0x3c, 0x81, 0xd0, 0x64, 0xf8, 0x86, 0x1a, 0x0b, 0x40, 0x58, 0xc9,
  0x33, 0x49, 0xb8, 0x99, 0xc6, 0x2e, 0x94, 0x70, 0xee, 0x09, 0x88, 0xe1, 0x5c, 0x4e, 0x6c, 0x22,
  0x72, 0xa7, 0x2a, 0x21, 0xdd, 0xd7, 0x1d, 0xfc, 0x63, 0x15, 0x0b, 0xde, 0x06, 0x9c, 0xf3, 0x28,
  0xf3, 0xac, 0x4a, 0xa8, 0xb5, 0x50, 0xca, 0x9b, 0xcc, 0x0a, 0x04, 0xfe, 0x3f, 0x98, 0x68, 0x81,
  0xac, 0x24, 0x53, 0xea, 0x1f, 0x1c, 0x6e, 0x5e, 0xca, 0xe8, 0x31, 0x0d, 0x08, 0x12, 0xf3, 0x26,
  0xf8, 0x5e, 0xeb, 0x10, 0x27, 0xae, 0xaa, 0xc3, 0xad, 0x6c, 0xc1, 0x89, 0xdb, 0x7d, 0x5a, 0x12,
  0x55, 0xad, 0x11, 0x19, 0xa1, 0xa9, 0x8f, 0x0b, 0x6d, 0x78, 0x8d, 0x1c, 0xdf, 0xe5, 0x63, 0x82,
  0x0b, 0x7d, 0x23, 0x04, 0xb4, 0x75, 0x8c, 0xed, 0x77, 0xfc, 0x1a, 0x85, 0x29, 0x11, 0xe0, 0x61,
]);

/* 1. Set the key alias. */
let keyAlias = 'RSA_sample';
/* 2. Encapsulate the key property set and key material. */
let properties: Array<huks.HuksParam> = [
  {
    tag: huks.HuksTag.HUKS_TAG_ALGORITHM,
    value: huks.HuksKeyAlg.HUKS_ALG_RSA
  },
  {
    tag: huks.HuksTag.HUKS_TAG_KEY_SIZE,
    value: huks.HuksKeySize.HUKS_RSA_KEY_SIZE_2048
  },
  {
    // This tag indicates the usage of the imported key, which cannot be changed after the import.
    tag: huks.HuksTag.HUKS_TAG_PURPOSE,
    value: huks.HuksKeyPurpose.HUKS_KEY_PURPOSE_ENCRYPT | huks.HuksKeyPurpose.HUKS_KEY_PURPOSE_DECRYPT
  },
  {
    // This tag indicates the type of the key to be imported.
    tag: huks.HuksTag.HUKS_TAG_IMPORT_KEY_TYPE,
    // The value here means to import a key parit. To import a public key, set value to HUKS_KEY_TYPE_PUBLIC_KEY.
    value: huks.HuksImportKeyType.HUKS_KEY_TYPE_KEY_PAIR
  },
]
let options: huks.HuksOptions = {
  properties: properties,
  inData: rsa2048KeyPairMaterial
};
/* 3. Import the key in plaintext. */
try {
  huks.importKeyItem(keyAlias, options, (error, data) => {
    if (error) {
      console.error(`callback: importKeyItem failed` + error);
    } else {
      console.info(`callback: importKeyItem success`);
    }
  });
} catch (error) {
  console.error(`callback: importKeyItem input arg invalid` + error);
}
```


## Verification

Use [huks.isKeyItemExist](../../reference/apis-universal-keystore-kit/js-apis-huks.md#huksiskeyitemexist9) to check whether the key exists. If the key exists, the key is successfully imported.

```ts
import { huks } from '@kit.UniversalKeystoreKit';

let keyAlias = 'AES256Alias_sample';
let isKeyExist = false;

let keyProperties: Array<huks.HuksParam> = [
  {
    tag: huks.HuksTag.HUKS_TAG_ALGORITHM,
    value: huks.HuksKeyAlg.HUKS_ALG_AES
  }
]
let huksOptions: huks.HuksOptions = {
  properties: keyProperties, // It cannot be empty.
  inData: new Uint8Array(new Array()) // It cannot be empty.
}
try {
  huks.isKeyItemExist(keyAlias, huksOptions, (error, data) => {
    if (error) {
      console.error(`callback: isKeyItemExist failed, ` + JSON.stringify(error));
    } else {
      if (data !== null && data.valueOf() !== null) {
        isKeyExist = data.valueOf();
        console.info(`callback: isKeyItemExist success, isKeyExist = ${isKeyExist}`);
      }
    }
  });
} catch (error) {
  console.error(`callback: isKeyItemExist input arg invalid, ` + JSON.stringify(error));
}
```