harmony 鸿蒙Converting a Compressed or Uncompressed ECC Public Key (ArkTS)

2025-06-12
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Converting a Compressed or Uncompressed ECC Public Key (ArkTS)

You can generate a public key object (PubKey) from ECC public key data or obtain the ECC public key data from a public key (PubKey) object. Currently, only the compressed/uncompressed public key data that complies with the ECC X.509 standard is supported.
The public key data mentioned in this topic is a complete X509 public key. For details about the operations on point data, see Converting Compressed or Uncompressed ECC Point Data.
For details about the ECC algorithm specifications, see ECC.
You can specify the string parameter format to set the format of the ECC public key to obtain. To obtain a compressed public key that complies with the X.509 standard, set format to X509|COMPRESSED. To obtain an uncompressed public key, set format to X509|UNCOMPRESSED.

Converting Uncompressed Public Key Data to Compressed Public Key Data

Encapsulate uncompressed ECC public key data of the Uint8Array type into a DataBlob object. Either the public key or private key can be passed in. In this example, an uncompressed public key is passed in.
Call cryptoFramework.createAsyKeyGenerator with the string parameter ‘ECC_BrainPoolP256r1’ to create an asymmetric key generator (AsyKeyGenerator) object for a 256-bit ECC key pair.
Call AsyKeyGenerator.convertKey to convert the DataBlob object into an asymmetric key (KeyPair) object.
Call PubKey.getEncodedDer with format set to ‘X509|COMPRESSED’ to obtain the byte stream of the compressed public key.

import { cryptoFramework } from '@kit.CryptoArchitectureKit';

async function eccPubUncompressedToCompressed() {
  let pkData = new Uint8Array([48, 90, 48, 20, 6, 7, 42, 134, 72, 206, 61, 2, 1, 6, 9, 43, 36, 3, 3, 2, 8, 1, 1, 7, 3, 66, 0, 4, 143, 39, 57, 249, 145, 50, 63, 222, 35, 70, 178, 121, 202, 154, 21, 146, 129, 75, 76, 63, 8, 195, 157, 111, 40, 217, 215, 148, 120, 224, 205, 82, 83, 92, 185, 21, 211, 184, 5, 19, 114, 33, 86, 85, 228, 123, 242, 206, 200, 98, 178, 184, 130, 35, 232, 45, 5, 202, 189, 11, 46, 163, 156, 152]);
  let pubKeyBlob: cryptoFramework.DataBlob = { data: pkData };
  let generator = cryptoFramework.createAsyKeyGenerator('ECC_BrainPoolP256r1');
  let keyPair = await generator.convertKey(pubKeyBlob, null);
  let returnBlob = keyPair.pubKey.getEncodedDer('X509|COMPRESSED');
  console.info('returnBlob data:' + returnBlob.data);
}