# Converting Binary Data into an Asymmetric Key Pair


This topic uses RSA, ECC, and SM2 as an example to describe how to convert binary data into an asymmetric key pair (**KeyPair**). That is, convert a piece of external or internal binary data into a **KeyPair** object for subsequent operations, such as encryption and decryption.


> **NOTE**
>
> The asymmetric key conversion must comply with the following requirements: 
>
> - The public key must use the ASN.1 syntax and DER encoding format and comply with X.509 specifications.
>
> - The private key must use the ASN.1 syntax and DER encoding format and comply with PKCS\#8 specifications.


## Converting Binary Data into an RSA Key Pair

For details about the algorithm specifications, see [RSA](crypto-asym-key-generation-conversion-spec.md#rsa).

1. Obtain the binary data of the RSA public key or private key and encapsulate the data into a **DataBlob** object.

   Either the public key or private key can be passed in. In this example, the public key is passed in.

2. Use [cryptoFramework.createAsyKeyGenerator](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#cryptoframeworkcreateasykeygenerator) 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.

3. Use [AsyKeyGenerator.convertKey](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#convertkey-3) to convert the binary data into an asymmetric key pair (**KeyPair**).

- Example: Convert binary data into an RSA key pair (using ballback-based APIs).
  ```ts
  import cryptoFramework from '@ohos.security.cryptoFramework';

  function convertAsyKey() {
    let rsaGenerator = cryptoFramework.createAsyKeyGenerator('RSA1024');
    let pkVal = new Uint8Array([48, 129, 159, 48, 13, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 1, 5, 0, 3, 129, 141, 0, 48, 129, 137, 2, 129, 129, 0, 174, 203, 113, 83, 113, 3, 143, 213, 194, 79, 91, 9, 51, 142, 87, 45, 97, 65, 136, 24, 166, 35, 5, 179, 42, 47, 212, 79, 111, 74, 134, 120, 73, 67, 21, 19, 235, 80, 46, 152, 209, 133, 232, 87, 192, 140, 18, 206, 27, 106, 106, 169, 106, 46, 135, 111, 118, 32, 129, 27, 89, 255, 183, 116, 247, 38, 12, 7, 238, 77, 151, 167, 6, 102, 153, 126, 66, 28, 253, 253, 216, 64, 20, 138, 117, 72, 15, 216, 178, 37, 208, 179, 63, 204, 39, 94, 244, 170, 48, 190, 21, 11, 73, 169, 156, 104, 193, 3, 17, 100, 28, 60, 50, 92, 235, 218, 57, 73, 119, 19, 101, 164, 192, 161, 197, 106, 105, 73, 2, 3, 1, 0, 1]);
    let pkBlob: cryptoFramework.DataBlob = { data: pkVal };
    rsaGenerator.convertKey(pkBlob, null, (err, keyPair) => {
      if (err) {
        console.error(`convertKey failed, ${err.code}, ${err.message}`);
        return;
      }
      console.info('convertKey success');
    });
  }
  ```

## Converting Binary Data into an ECC Key Pair

For details about the algorithm specifications, see [ECC](crypto-asym-key-generation-conversion-spec.md#ecc).

1. Obtain the binary data of the ECC public key or private key and encapsulate the data into a **DataBlob** object.

   Either the public key or private key can be passed in. As shown in the following example, the public key and private key are passed in separately.

2. Use [cryptoFramework.createAsyKeyGenerator](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#cryptoframeworkcreateasykeygenerator) with the string parameter **'ECC256'** to create an asymmetric key generator (**AsyKeyGenerator**) object for a 256-bit ECC key pair.

3. Use [AsyKeyGenerator.convertKey](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#convertkey-3) to convert the binary data into an asymmetric key pair (**KeyPair**).

- Example: Convert binary data into an ECC key pair (using ballback-based APIs).
  ```ts
  import cryptoFramework from '@ohos.security.cryptoFramework';

  function convertEccAsyKey() {
    let pubKeyArray = new Uint8Array([48, 89, 48, 19, 6, 7, 42, 134, 72, 206, 61, 2, 1, 6, 8, 42, 134, 72, 206, 61, 3, 1, 7, 3, 66, 0, 4, 83, 96, 142, 9, 86, 214, 126, 106, 247, 233, 92, 125, 4, 128, 138, 105, 246, 162, 215, 71, 81, 58, 202, 121, 26, 105, 211, 55, 130, 45, 236, 143, 55, 16, 248, 75, 167, 160, 167, 106, 2, 152, 243, 44, 68, 66, 0, 167, 99, 92, 235, 215, 159, 239, 28, 106, 124, 171, 34, 145, 124, 174, 57, 92]);
    let priKeyArray = new Uint8Array([48, 49, 2, 1, 1, 4, 32, 115, 56, 137, 35, 207, 0, 60, 191, 90, 61, 136, 105, 210, 16, 27, 4, 171, 57, 10, 61, 123, 40, 189, 28, 34, 207, 236, 22, 45, 223, 10, 189, 160, 10, 6, 8, 42, 134, 72, 206, 61, 3, 1, 7]);
    let pubKeyBlob: cryptoFramework.DataBlob = { data: pubKeyArray };
    let priKeyBlob: cryptoFramework.DataBlob = { data: priKeyArray };
    let generator = cryptoFramework.createAsyKeyGenerator('ECC256');
    generator.convertKey(pubKeyBlob, priKeyBlob, (error, data) => {
      if (error) {
        console.error(`convertKey failed, ${error.code}, ${error.message}`);
        return;
      }
      console.info('convertKey success');
    });
  }
  ```

## Converting Binary Data into an SM2 Key Pair

For details about the algorithm specifications, see [SM2](crypto-asym-key-generation-conversion-spec.md#sm2).

1. Obtain the binary data of the SM2 public key or private key and encapsulate the data into a **DataBlob** object.

   Either the public key or private key can be passed in. As shown in the following example, the public key and private key are passed in separately.

2. Use [cryptoFramework.createAsyKeyGenerator](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#cryptoframeworkcreateasykeygenerator) with the string parameter **'SM2_256'** to create an asymmetric key generator (**AsyKeyGenerator**) object for a 256-bit SM2 key pair.

3. Use [AsyKeyGenerator.convertKey](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#convertkey-3) to convert the binary data into an asymmetric key pair (**KeyPair**).

- Example: Convert binary data into an SM2 key pair (using ballback-based APIs).
  ```ts
  import cryptoFramework from '@ohos.security.cryptoFramework';

  function convertSM2AsyKey() {
    let pubKeyArray = new Uint8Array([48, 89, 48, 19, 6, 7, 42, 134, 72, 206, 61, 2, 1, 6, 8, 42, 129, 28, 207, 85, 1, 130, 45, 3, 66, 0, 4, 90, 3, 58, 157, 190, 248, 76, 7, 132, 200, 151, 208, 112, 230, 96, 140, 90, 238, 211, 155, 128, 109, 248, 40, 83, 214, 78, 42, 104, 106, 55, 148, 249, 35, 61, 32, 221, 135, 143, 100, 45, 97, 194, 176, 52, 73, 136, 174, 40, 70, 70, 34, 103, 103, 161, 99, 27, 187, 13, 187, 109, 244, 13, 7]);
    let priKeyArray = new Uint8Array([48, 49, 2, 1, 1, 4, 32, 54, 41, 239, 240, 63, 188, 134, 113, 31, 102, 149, 203, 245, 89, 15, 15, 47, 202, 170, 60, 38, 154, 28, 169, 189, 100, 251, 76, 112, 223, 156, 159, 160, 10, 6, 8, 42, 129, 28, 207, 85, 1, 130, 45]);
    let pubKeyBlob: cryptoFramework.DataBlob = { data: pubKeyArray };
    let priKeyBlob: cryptoFramework.DataBlob = { data: priKeyArray };
    let generator = cryptoFramework.createAsyKeyGenerator('SM2_256');
    generator.convertKey(pubKeyBlob, priKeyBlob, (error, data) => {
      if (error) {
        console.error(`convertKey failed, ${error.code}, ${error.message}`);
        return;
      }
      console.info('convertKey success');
    });
  }
  ```