React Native Requires Chilkat v11.0.0+

RSA Encryption -- Same Key Different Results

See more RSA Examples

The RSA encryption algorithm produces different results for each call, even when encrypting the same data with the same key. Decryption however, will produce the correct results. This example demonstrates.

*** The reason this occurs is that RSA encryption uses PKCS1 v1.5 padding, and this padding scheme uses random bytes. It is random bytes in the padding that causes the result to be different each time.

React Native

import { PrivateKey, PublicKey, Rsa } from '@chilkat/react-native'

function chilkatExample() {
  // This example assumes the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  const rsa = new Rsa();

  const pubKeyXml = '<RSAPublicKey><Modulus>xxyv1RDPU0MvfFIIa98HppXdcuI7zSu8uIqyGAy/VoxPvxZFX0acajznvjVRHipHbpcO6ryo2LwXUPf89qOqLb3Qd1lfD2ZnH+TQ6MZXNxfFRxTpTUd+tTR4EBYpd2t6kzq8ZRJYLdlviaMQQqUEwR54k7Op5HJYVKUcHIkP1xE=</Modulus><Exponent>AQAB</Exponent></RSAPublicKey>';

  const privKeyXml = '<RSAKeyValue><Modulus>xxyv1RDPU0MvfFIIa98HppXdcuI7zSu8uIqyGAy/VoxPvxZFX0acajznvjVRHipHbpcO6ryo2LwXUPf89qOqLb3Qd1lfD2ZnH+TQ6MZXNxfFRxTpTUd+tTR4EBYpd2t6kzq8ZRJYLdlviaMQQqUEwR54k7Op5HJYVKUcHIkP1xE=</Modulus><Exponent>AQAB</Exponent><P>4cpW9fvG99Jsz8/AO7PDHTl+pPRAglksrR2kClLV2g9DEeFe/bvmCxLUgMCJ+0eGQ1zA6aA7McKr13zTQ7jKpQ==</P><Q>4cCS/kFlq/P1ExF37Fkh4pCodOEGutepLEG7Q/KljT3ZGlAY+2l8fGu4f+hrkUuGoFl7NOMaJflULoPIgQaq/Q==</Q><DP>lkjcSsvzqh3YKRXJiLNkyf3rypV8noYGU4+oEOsDxilkZfFRDafUPUiiQrRk4ui/d/SzvozU+ZDuWfaOk8PatQ==</DP><DQ>SYCD25i7W8Mwdibn3uIecEAdOQDTSh5RjIFSUYs9b8FFYJXXrHPp/jCsf6jS7RmkGa1Iui1/JAIL8KEjtS7QmQ==</DQ><InverseQ>EDAJa3TpNdPQ3GIdBpnTgFTQY5A60DcszsUW/iCYoXQdPVJ9BLBxVTe9jiLzGuNuzLkVBwQlCy0Bf84hACRV9A==</InverseQ><D>cMFdDYKkddlRNczaugOmOH8b1egpx2liSPs6GYZ2gFObAXJiPK8m+r6c2ckls7hrlUP0DZhi4cG6Tn7xANb0Ek17P7QquVhQYOmFy/YHzm+IJbcwwq7pJHhZBhtcjyXqfUZ+BADGE//GQbrSVwVltpOj5KcxG88NAprLn2MMxfE=</D></RSAKeyValue>';

  const pubKey = new PublicKey();
  try {
    pubKey.loadFromString(pubKeyXml);
  } catch {
    console.log(pubKey.lastErrorText);
    return;
  }

  const privKey = new PrivateKey();
  try {
    privKey.loadXml(privKeyXml);
  } catch {
    console.log(privKey.lastErrorText);
    return;
  }

  try {
    rsa.usePublicKey(pubKey);
  } catch {
    console.log(rsa.lastErrorText);
    return;
  }

  // Encrypt a string and return the encrypted data base64-encoded:
  rsa.encodingMode = 'base64';

  const plainText = 'RSA gives different results with each call, weird but OK';

  let usePrivateKey = false;
  const encryptedStr1 = rsa.encryptStringENC(plainText, usePrivateKey);
  console.log(encryptedStr1);

  // Do it again. The results are different...
  const encryptedStr2 = rsa.encryptStringENC(plainText, usePrivateKey);
  console.log(encryptedStr2);

  // Now decrypt both strings, and the results are correct
  // in both cases:
  const rsa2 = new Rsa();
  try {
    rsa2.usePrivateKey(privKey);
  } catch {
    console.log(rsa.lastErrorText);
    return;
  }

  rsa2.encodingMode = 'base64';
  usePrivateKey = true;

  const decryptedStr1 = rsa2.decryptStringENC(encryptedStr1, usePrivateKey);
  console.log(decryptedStr1);

  const decryptedStr2 = rsa2.decryptStringENC(encryptedStr2, usePrivateKey);
  console.log(decryptedStr2);
}