Exporting a Key (ArkTS)
This topic walks you through on how to export the public key of a persistently stored asymmetric key. Currently, HUKS supports export of the ECC, RSA, Ed25519, X25519, and SM2 public keys.
NOTE
Mini-system devices support export of only the RSA public keys.
The Group Key feature is supported since API version 23.
How to Develop
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Specify the key alias. For details about the naming rules, see Key Generation Overview and Algorithm Specifications.
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Use exportKeyItem to export the key based on the specified keyAlias and options. options is a reserved parameter and is left empty currently.
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In the HuksReturnResult object returned, the public key is in the outData field in the DER format defined in X.509. For details about the format, see Public Key Material Format.
import { huks } from '@kit.UniversalKeystoreKit';
/* 1. Set the key alias. */
let keyAlias = 'keyAlias';
/* Leave options empty. */
let emptyOptions: huks.HuksOptions = {
properties: []
};
let properties1: huks.HuksParam[] = [
{
tag: huks.HuksTag.HUKS_TAG_ALGORITHM,
value: huks.HuksKeyAlg.HUKS_ALG_DH
},
{
tag: huks.HuksTag.HUKS_TAG_PURPOSE,
value: huks.HuksKeyPurpose.HUKS_KEY_PURPOSE_AGREE
},
{
tag: huks.HuksTag.HUKS_TAG_KEY_SIZE,
value: huks.HuksKeySize.HUKS_DH_KEY_SIZE_2048
}
];
let huksOptions: huks.HuksOptions = {
properties: properties1,
inData: new Uint8Array([])
}
/* 3. Generate a key. */
function generateKeyItem(keyAlias: string, huksOptions: huks.HuksOptions) {
return new Promise<void>((resolve, reject) => {
try {
huks.generateKeyItem(keyAlias, huksOptions, (error, data) => {
if (error) {
reject(error);
} else {
resolve(data);
}
});
} catch (error) {
throw (error as Error);
}
});
}
async function publicGenKeyFunc(keyAlias: string, huksOptions: huks.HuksOptions): Promise<string> {
console.info(`enter promise generateKeyItem`);
try {
await generateKeyItem(keyAlias, huksOptions)
.then((data) => {
console.info(`promise: generateKeyItem success, data = ${JSON.stringify(data)}`);
})
.catch((error: Error) => {
console.error(`promise: generateKeyItem failed, ${JSON.stringify(error)}`);
});
return 'Success';
} catch (error) {
console.error(`promise: generateKeyItem input arg invalid, ${JSON.stringify(error)}`);
return 'Failed';
}
}
async function testGenKey(): Promise<string> {
let ret = await publicGenKeyFunc(keyAlias, huksOptions);
return ret;
}
function check(): string {
try {
/* 1. Generate a key. */
testGenKey()
/* 2. Export the key. */
huks.exportKeyItem(keyAlias, emptyOptions, (error, data) => {
if (error) {
console.error(`callback: exportKeyItem failed, ` + error);
} else {
console.info(`callback: exportKeyItem success, data = ${JSON.stringify(data)}`);
}
});
return 'Success';
} catch (error) {
console.error(`callback: exportKeyItem input arg invalid, ${JSON.stringify(error)}`);
return 'Failed';
}
}