Randomly Generating an Asymmetric Key Pair

This topic uses RSA and SM2 as an example to describe how to generate an asymmetric key pair (KeyPair) and obtain the binary data.

The KeyPair object created can be used for subsequent encryption and decryption operations, and the binary data can be used for key storage and transfer.

Randomly Generating an RSA Key Pair

For details about the algorithm specifications, see RSA.

1. Use cryptoFramework.createAsyKeyGenerator with the string parameter 'RSA1024|PRIMES_2' to create an asymmetric key generator (AsyKeyGenerator) object for a 1024-bit RSA key with two primes.

2. Use AsyKeyGenerator.generateKeyPair to randomly generate an asymmetric key pair (KeyPair).

   The KeyPair object includes a public key (PubKey) and a private key (PriKey).

3. Use PubKey.getEncoded to obtain the binary data of the public key, and use PriKey.getEncoded to obtain the binary data of the private key.

Example: Randomly generate an RSA key pair (using promise-based APIs).

import cryptoFramework from '@ohos.security.cryptoFramework';

function generateAsyKey() {
  // Create an AsyKeyGenerator instance.
  let rsaGenerator = cryptoFramework.createAsyKeyGenerator('RSA1024|PRIMES_2');
  // Use AsyKeyGenerator to randomly generate an asymmetric key pair.
  let keyGenPromise = rsaGenerator.generateKeyPair();
  keyGenPromise.then(keyPair => {
    let pubKey = keyPair.pubKey;
    let priKey = keyPair.priKey;
    // Obtain the binary data of the asymmetric key pair.
    let pkBlob = pubKey.getEncoded();
    let skBlob = priKey.getEncoded();
    console.info('pk bin data' + pkBlob.data);
    console.info('sk bin data' + skBlob.data);
  });
}

Randomly Generating an SM2 Key Pair

For details about the algorithm specifications, see SM2.

1. Use cryptoFramework.createAsyKeyGenerator with the string parameter 'SM2_256' to create an asymmetric key generator (AsyKeyGenerator) object for a 256-bit SM2 key pair.

2. Use AsyKeyGenerator.generateKeyPair to randomly generate an asymmetric key pair (KeyPair).

   The KeyPair object includes a public key (PubKey) and a private key (PriKey).

3. Use PubKey.getEncoded to obtain the binary data of the public key, and use PriKey.getEncoded to obtain the binary data of the private key.

Example: Randomly generate an SM2 key pair (using promise-based APIs).

import cryptoFramework from '@ohos.security.cryptoFramework';

function generateSM2Key() {
  // Create an AsyKeyGenerator instance.
  let sm2Generator = cryptoFramework.createAsyKeyGenerator('SM2_256');
  // Use AsyKeyGenerator to randomly generate an asymmetric key pair.
  let keyGenPromise = sm2Generator.generateKeyPair();
  keyGenPromise.then(keyPair => {
    let pubKey = keyPair.pubKey;
    let priKey = keyPair.priKey;
    // Obtain the binary data of the asymmetric key pair.
    let pkBlob = pubKey.getEncoded();
    let skBlob = priKey.getEncoded();
    console.info('pk bin data' + pkBlob.data);
    console.info('sk bin data' + skBlob.data);
  });
}