harmony 鸿蒙Converting a PEM String into an Asymmetric Key Pair (ArkTS)

2025-06-12
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Converting a PEM String into an Asymmetric Key Pair (ArkTS)

This topic walks you through on how to convert a string in PEM format into an RSA asymmetric key pair (KeyPair).

NOTE

The convertPemKey operation must comply with the following requirements:

The public key must comply with X.509 specifications, PKCS #1 specifications, and PEM encoding format.

The private key must comply with the PKCS #8 or PKCS #1 specifications and the PEM encoding format.

Currently, only RSA asymmetric keys can be converted.

Converting a String in PEM Format into an RSA Key Pair

For details about the algorithm specifications, see RSA.

Call cryptoFramework.createAsyKeyGenerator with the string parameter ‘RSA1024’ to create an asymmetric key generator (AsyKeyGenerator) object for a 1024-bit RSA key with two primes.

The default number of primes for creating an RSA asymmetric key is 2. The PRIMES_2 parameter is omitted in the string parameter here.

Call AsyKeyGenerator.convertPemKey to convert the binary data into an asymmetric key pair (KeyPair).
Call AsyKeyGenerator.getEncodedPem to convert the public key in the asymmetric key object into the PKCS #1 or X509 format and the private key into the PKCS #1 or PKCS #8 format.
Example: Convert a string in PEM format into an RSA key pair (using promise-based APIs).

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

  let priKeyPkcs1Str1024: string  =
    "-----BEGIN RSA PRIVATE KEY-----\n"
    + "MIICXQIBAAKBgQCwIN3mr21+N96ToxnVnaS+xyK9cNRAHiHGgrbjHw6RAj3V+l+W\n"
    + "Y68IhIe3DudVlzE9oMjeOQwkMkq//HCxNlIlFR6O6pa0mrXSwPRE7YKG97CeKk2g\n"
    + "YOS8YEh8toAvm7xKbiLkXuuMlxrjP2j/mb5iI/UASFSPZiQ/IyxDr0AQaQIDAQAB\n"
    + "AoGAEvBFzBNa+7J4PXnRQlYEK/tvsd0bBZX33ceacMubHl6WVZbphltLq+fMTBPP\n"
    + "LjXmtpC+aJ7Lvmyl+wTi/TsxE9vxW5JnbuRT48rnZ/Xwq0eozDeEeIBRrpsr7Rvr\n"
    + "7ctrgzr4m4yMHq9aDgpxj8IR7oHkfwnmWr0wM3FuiVlj650CQQDineeNZ1hUTkj4\n"
    + "D3O+iCi3mxEVEeJrpqrmSFolRMb+iozrIRKuJlgcOs+Gqi2fHfOTTL7LkpYe8SVg\n"
    + "e3JxUdVLAkEAxvcZXk+byMFoetrnlcMR13VHUpoVeoV9qkv6CAWLlbMdgf7uKmgp\n"
    + "a1Yp3QPDNQQqkPvrqtfR19JWZ4uy1qREmwJALTU3BjyBoH/liqb6fh4HkWk75Som\n"
    + "MzeSjFIOubSYxhq5tgZpBZjcpvUMhV7Zrw54kwASZ+YcUJvmyvKViAm9NQJBAKF7\n"
    + "DyXSKrem8Ws0m1ybM7HQx5As6l3EVhePDmDQT1eyRbKp+xaD74nkJpnwYdB3jyyY\n"
    + "qc7A1tj5J5NmeEFolR0CQQCn76Xp8HCjGgLHw9vg7YyIL28y/XyfFyaZAzzK+Yia\n"
    + "akNwQ6NeGtXSsuGCcyyfpacHp9xy8qXQNKSkw03/5vDO\n"
    + "-----END RSA PRIVATE KEY-----\n";
  let publicPkcs1Str1024: string  =
    "-----BEGIN RSA PUBLIC KEY-----\n"
    + "MIGJAoGBALAg3eavbX433pOjGdWdpL7HIr1w1EAeIcaCtuMfDpECPdX6X5ZjrwiE\n"
    + "h7cO51WXMT2gyN45DCQySr/8cLE2UiUVHo7qlrSatdLA9ETtgob3sJ4qTaBg5Lxg\n"
    + "SHy2gC+bvEpuIuRe64yXGuM/aP+ZvmIj9QBIVI9mJD8jLEOvQBBpAgMBAAE=\n"
    + "-----END RSA PUBLIC KEY-----\n";
  async function TestPkcs1ToPkcs8ByPromise() {
    let asyKeyGenerator = cryptoFramework.createAsyKeyGenerator('RSA1024');
    let keyPair = await asyKeyGenerator.convertPemKey(publicPkcs1Str1024, priKeyPkcs1Str1024);
    let priPemKey = keyPair.priKey;
    let pubPemKey = keyPair.pubKey;
    let priString = priPemKey.getEncodedPem('PKCS8');
    let pubString = pubPemKey.getEncodedPem('X509');
    console.info("[promise]TestPkcs1ToPkcs8ByPromise priString output is " + priString);
    console.info("[promise]TestPkcs1ToPkcs8ByPromise pubString output is " + pubString);
  }

Example: Convert a string in PEM format into an RSA key pair (using the synchronous API convertPemKeySync).

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

  let priKeyPkcs1Str1024: string  =
    "-----BEGIN RSA PRIVATE KEY-----\n"
    + "MIICXQIBAAKBgQCwIN3mr21+N96ToxnVnaS+xyK9cNRAHiHGgrbjHw6RAj3V+l+W\n"
    + "Y68IhIe3DudVlzE9oMjeOQwkMkq//HCxNlIlFR6O6pa0mrXSwPRE7YKG97CeKk2g\n"
    + "YOS8YEh8toAvm7xKbiLkXuuMlxrjP2j/mb5iI/UASFSPZiQ/IyxDr0AQaQIDAQAB\n"
    + "AoGAEvBFzBNa+7J4PXnRQlYEK/tvsd0bBZX33ceacMubHl6WVZbphltLq+fMTBPP\n"
    + "LjXmtpC+aJ7Lvmyl+wTi/TsxE9vxW5JnbuRT48rnZ/Xwq0eozDeEeIBRrpsr7Rvr\n"
    + "7ctrgzr4m4yMHq9aDgpxj8IR7oHkfwnmWr0wM3FuiVlj650CQQDineeNZ1hUTkj4\n"
    + "D3O+iCi3mxEVEeJrpqrmSFolRMb+iozrIRKuJlgcOs+Gqi2fHfOTTL7LkpYe8SVg\n"
    + "e3JxUdVLAkEAxvcZXk+byMFoetrnlcMR13VHUpoVeoV9qkv6CAWLlbMdgf7uKmgp\n"
    + "a1Yp3QPDNQQqkPvrqtfR19JWZ4uy1qREmwJALTU3BjyBoH/liqb6fh4HkWk75Som\n"
    + "MzeSjFIOubSYxhq5tgZpBZjcpvUMhV7Zrw54kwASZ+YcUJvmyvKViAm9NQJBAKF7\n"
    + "DyXSKrem8Ws0m1ybM7HQx5As6l3EVhePDmDQT1eyRbKp+xaD74nkJpnwYdB3jyyY\n"
    + "qc7A1tj5J5NmeEFolR0CQQCn76Xp8HCjGgLHw9vg7YyIL28y/XyfFyaZAzzK+Yia\n"
    + "akNwQ6NeGtXSsuGCcyyfpacHp9xy8qXQNKSkw03/5vDO\n"
    + "-----END RSA PRIVATE KEY-----\n";
  let publicPkcs1Str1024: string  =
    "-----BEGIN RSA PUBLIC KEY-----\n"
    + "MIGJAoGBALAg3eavbX433pOjGdWdpL7HIr1w1EAeIcaCtuMfDpECPdX6X5ZjrwiE\n"
    + "h7cO51WXMT2gyN45DCQySr/8cLE2UiUVHo7qlrSatdLA9ETtgob3sJ4qTaBg5Lxg\n"
    + "SHy2gC+bvEpuIuRe64yXGuM/aP+ZvmIj9QBIVI9mJD8jLEOvQBBpAgMBAAE=\n"
    + "-----END RSA PUBLIC KEY-----\n";
  function TestPkcs1ToPkcs8BySync() {
    let asyKeyGenerator = cryptoFramework.createAsyKeyGenerator('RSA1024');
    try {
      let keyPairData = asyKeyGenerator.convertPemKeySync(publicPkcs1Str1024, priKeyPkcs1Str1024);
      if (keyPairData !== null) {
        console.info('[Sync]: convert pem key pair success');
      } else {
        console.error("[Sync]: convert pem key pair result fail!");
      }
      let priPemKey = keyPairData.priKey;
      let pubPemKey = keyPairData.pubKey;
      let priString = priPemKey.getEncodedPem('PKCS8');
      let pubString = pubPemKey.getEncodedPem('X509');
      console.info("[Sync]TestPkcs1ToPkcs8BySync priString output is " + priString);
      console.info("[Sync]TestPkcs1ToPkcs8BySync pubString output is " + pubString);
    } catch (e) {
      console.error(`Sync error, ${e.code}, ${e.message}`);
    }
  }