HarmonyOS RSA如何使用现有的公私钥进行分段加解密？

Question

如题：HarmonyOS RSA如何使用现有的公私钥进行分段加解密？

Answer 1

示例参考如下：

import { cryptoFramework } from '@kit.CryptoArchitectureKit';
import { buffer, util } from '@kit.ArkTS';
import promptAction from '@ohos.promptAction'

@Entry
@Component
struct Crypto {
  @State message: string = '点击开始';
  @State outMessage: string = ''

  build() {
    Column() {
      Text(this.message)
        .fontSize(50)
        .fontWeight(FontWeight.Bold)
        .onClick(() => {
          rsaEncryptLongMessage()
        })
      Text(this.outMessage)
        .fontSize(14)
        .fontWeight(FontWeight.Normal)
        .width('80%')
    }
    .height('100%')
    .width('100%')
    .justifyContent(FlexAlign.Center)
    .alignItems(HorizontalAlign.Center)

  }
}

// 分段加密消息
function rsaEncryptBySegment(pubKey: cryptoFramework.PubKey, plainText: cryptoFramework.DataBlob) {
  let cipher = cryptoFramework.createCipher('RSA1024|PKCS1');
  cipher.initSync(cryptoFramework.CryptoMode.ENCRYPT_MODE, pubKey, null);
  let plainTextSplitLen = 64;
  let cipherText = new Uint8Array();
  for (let i = 0; i < plainText.data.length; i += plainTextSplitLen) {
    let updateMessage = plainText.data.subarray(i, i + plainTextSplitLen);
    let updateMessageBlob: cryptoFramework.DataBlob = { data: updateMessage };
    // 将原文按64字符进行拆分，循环调用doFinal进行加密，使用1024bit密钥时，每次加密生成128字节长度的密文
    let updateOutput = cipher.doFinalSync(updateMessageBlob);
    let mergeText = new Uint8Array(cipherText.length + updateOutput.data.length);
    mergeText.set(cipherText);
    mergeText.set(updateOutput.data, cipherText.length);
    cipherText = mergeText;
  }
  let cipherBlob: cryptoFramework.DataBlob = { data: cipherText };
  return cipherBlob;
}

// 分段解密消息
function rsaDecryptBySegment(priKey: cryptoFramework.PriKey, cipherText: cryptoFramework.DataBlob) {
  let decoder = cryptoFramework.createCipher('RSA1024|PKCS1');
  decoder.initSync(cryptoFramework.CryptoMode.DECRYPT_MODE, priKey, null);
  let cipherTextSplitLen = 128; // RSA密钥每次加密生成的密文字节长度计算方式：密钥位数/8
  let decryptText = new Uint8Array();
  for (let i = 0; i < cipherText.data.length; i += cipherTextSplitLen) {
    let updateMessage = cipherText.data.subarray(i, i + cipherTextSplitLen);
    let updateMessageBlob: cryptoFramework.DataBlob = { data: updateMessage };
    // 将密文按128字节进行拆分解密，得到原文后进行拼接
    // 将原文按117字符进行拆分，循环调用doFinal进行加密，使用1024bit密钥时，每次加密生成128字节长度的密文
    let updateOutput = decoder.doFinalSync(updateMessageBlob);
    let mergeText = new Uint8Array(decryptText.length + updateOutput.data.length);
    mergeText.set(decryptText);
    mergeText.set(updateOutput.data, decryptText.length);
    decryptText = mergeText;
  }
  let decryptBlob: cryptoFramework.DataBlob = { data: decryptText };
  return decryptBlob;
}

function genKeyPairByData(pubKeyData: Uint8Array, priKeyData: Uint8Array) {
  let pubKeyBlob: cryptoFramework.DataBlob = { data: pubKeyData };
  let priKeyBlob: cryptoFramework.DataBlob = { data: priKeyData };
  let rsaGenerator = cryptoFramework.createAsyKeyGenerator('RSA1024|PRIMES_2');
  let keyPair = rsaGenerator.convertKeySync(pubKeyBlob, priKeyBlob);
  console.info('convertKey success');
  return keyPair;
}

function rsaEncryptLongMessage() {
  let message = "This is a long plainTest! This is a long plainTest! This is a long plainTest!" +
    "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!" +
    "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!" +
    "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!" +
    "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!" +
    "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!" +
    "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!" +
    "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!";
  let base64 = new util.Base64Helper();

  let pkData =
    "MIGfMA0GCSqG****RZI3a31Rh6P8xxxkGkfQIDAQAB";
  let skData =
    "MIICdgIBADANBgkqhkiGxxx6MKkZ8A==" /*new Uint8Array()*/;
  let pubKeyBlob = /*new Uint8Array()*/ base64.decodeSync(pkData);
  let priKeyBlob = base64.decodeSync(skData);
  let keyPair = genKeyPairByData(pubKeyBlob, priKeyBlob);
  let plainText: cryptoFramework.DataBlob =
    { data: new Uint8Array(/*base64.decodeSync(message2)*/buffer.from(message, 'utf-8').buffer) };
  let encryptText = rsaEncryptBySegment(keyPair.pubKey, plainText);

  let decryptText = rsaDecryptBySegment(keyPair.priKey, encryptText);
  console.info('decrypt plainText: ' + buffer.from(decryptText.data).toString('utf-8'));
}