RsaDecryptionOaepSha1NodeJsCrypto.js

const crypto = require('crypto')
const fs = require('fs');

console.log("RSA 2048 encryption OAEP SHA-1 string");

// # # # usually we would load the private key from a file or keystore # # #
// # # # here we use a hardcoded key for demonstration - don't do this in real programs # # #
var filenamePrivateKeyPem = "privatekey2048.pem";

// receiving the encrypted data, decryption
console.log("\n* * * decrypt the ciphertext with the RSA private key * * *");
var ciphertextReceivedBase64 = "In0CE7VSJlr6PT+fl9SCejWhNZYioVn1UzYaqYUms7Y63oi4xK/2Qrgyi5a3CnvappM1MHdDaZVc+bDzl/iBiUslkHcF8lWGD4YdKuJgtfSS8WBRuIxz78EFhU3TfMU3y0v0bhUUj1/6ZdO/p9j8KcNbnpEB8A9YW+bZC1qOO8ibnTNbb3RHQekafz6r9oAYsILNga1pi9ZlyXQPYi7VpWAeZmUOq+MHEgD/Nkq/oxkyMo/yf5SVk1ig8M5Lr6arj22r2ePpQ8j3onmN7aOTCWUhZ7FdLm7IiRYebZ3MWPWozt9O6BSNjALLDXm7NfKaYcgQ+bVXrA4k1M9f4M9OEA==";
console.log("ciphertextReceivedBase64: " + ciphertextReceivedBase64);
var privateKeyLoad = loadRsaPrivateKeyPem();
// use this in production
//var privateKeyLoad = fs.readFileSync(filenamePrivateKeyPem);
var ciphertextReceived = Buffer.from(ciphertextReceivedBase64, 'base64');
var decryptedtext = rsaDecryptionOaepSha1(privateKeyLoad, ciphertextReceived);
console.log("decryptedtext: " + decryptedtext);

function rsaDecryptionOaepSha1(privateKey, ciphertext) {
  var options = {key: privateKey,
            padding: crypto.constants.RSA_PKCS1_OAEP_PADDING,
            oaepHash: "sha1" };
  var decrypted = crypto.privateDecrypt(options, ciphertext);
  return decrypted.toString('utf8')
}

function loadRsaPrivateKeyPem() {
    const key = '-----BEGIN PRIVATE KEY-----\n' +
        'MIIEvgIBADANBgkqhkiG9w0BAQEFAASCBKgwggSkAgEAAoIBAQDwSZYlRn86zPi9\n' +
        'e1RTZL7QzgE/36zjbeCMyOhf6o/WIKeVxFwVbG2FAY3YJZIxnBH+9j1XS6f+ewjG\n' +
        'FlJY4f2IrOpS1kPiO3fmOo5N4nc8JKvjwmKtUM0t63uFFPfs69+7mKJ4w3tk2mSN\n' +
        '4gb8J9P9BCXtH6Q78SdOYvdCMspA1X8eERsdLb/jjHs8+gepKqQ6+XwZbSq0vf2B\n' +
        'MtaAB7zTX/Dk+ZxDfwIobShPaB0mYmojE2YAQeRq1gYdwwO1dEGk6E5J2toWPpKY\n' +
        '/IcSYsGKyFqrsmbw0880r1BwRDer4RFrkzp4zvY+kX3eDanlyMqDLPN+ghXT1lv8\n' +
        'snZpbaBDAgMBAAECggEBAIVxmHzjBc11/73bPB2EGaSEg5UhdzZm0wncmZCLB453\n' +
        'XBqEjk8nhDsVfdzIIMSEVEowHijYz1c4pMq9osXR26eHwCp47AI73H5zjowadPVl\n' +
        'uEAot/xgn1IdMN/boURmSj44qiI/DcwYrTdOi2qGA+jD4PwrUl4nsxiJRZ/x7PjL\n' +
        'hMzRbvDxQ4/Q4ThYXwoEGiIBBK/iB3Z5eR7lFa8E5yAaxM2QP9PENBr/OqkGXLWV\n' +
        'qA/YTxs3gAvkUjMhlScOi7PMwRX9HsrAeLKbLuC1KJv1p2THUtZbOHqrAF/uwHaj\n' +
        'ygUblFaa/BTckTN7PKSVIhp7OihbD04bSRrh+nOilcECgYEA/8atV5DmNxFrxF1P\n' +
        'ODDjdJPNb9pzNrDF03TiFBZWS4Q+2JazyLGjZzhg5Vv9RJ7VcIjPAbMy2Cy5BUff\n' +
        'EFE+8ryKVWfdpPxpPYOwHCJSw4Bqqdj0Pmp/xw928ebrnUoCzdkUqYYpRWx0T7YV\n' +
        'RoA9RiBfQiVHhuJBSDPYJPoP34kCgYEA8H9wLE5L8raUn4NYYRuUVMa+1k4Q1N3X\n' +
        'Bixm5cccc/Ja4LVvrnWqmFOmfFgpVd8BcTGaPSsqfA4j/oEQp7tmjZqggVFqiM2m\n' +
        'J2YEv18cY/5kiDUVYR7VWSkpqVOkgiX3lK3UkIngnVMGGFnoIBlfBFF9uo02rZpC\n' +
        '5o5zebaDImsCgYAE9d5wv0+nq7/STBj4NwKCRUeLrsnjOqRriG3GA/TifAsX+jw8\n' +
        'XS2VF+PRLuqHhSkQiKazGr2Wsa9Y6d7qmxjEbmGkbGJBC+AioEYvFX9TaU8oQhvi\n' +
        'hgA6ZRNid58EKuZJBbe/3ek4/nR3A0oAVwZZMNGIH972P7cSZmb/uJXMOQKBgQCs\n' +
        'FaQAL+4sN/TUxrkAkylqF+QJmEZ26l2nrzHZjMWROYNJcsn8/XkaEhD4vGSnazCu\n' +
        '/B0vU6nMppmezF9Mhc112YSrw8QFK5GOc3NGNBoueqMYy1MG8Xcbm1aSMKVv8xba\n' +
        'rh+BZQbxy6x61CpCfaT9hAoA6HaNdeoU6y05lBz1DQKBgAbYiIk56QZHeoZKiZxy\n' +
        '4eicQS0sVKKRb24ZUd+04cNSTfeIuuXZrYJ48Jbr0fzjIM3EfHvLgh9rAZ+aHe/L\n' +
        '84Ig17KiExe+qyYHjut/SC0wODDtzM/jtrpqyYa5JoEpPIaUSgPuTH/WhO3cDsx6\n' +
        '3PIW4/CddNs8mCSBOqTnoaxh\n' +
        '-----END PRIVATE KEY-----\n'; // important last crlf
    return key;
}