Card details encryption

import { privateDecrypt, createDecipheriv, constants } from 'node:crypto';

export function decryptCard(encryptedCard, privateKeyPem) {
  const cek = privateDecrypt(
    { key: privateKeyPem, padding: constants.RSA_PKCS1_OAEP_PADDING, oaepHash: 'sha256' },
    Buffer.from(encryptedCard.encryptedKey, 'base64'));
  const d = createDecipheriv('aes-256-gcm', cek, Buffer.from(encryptedCard.iv, 'base64'));
  d.setAAD(Buffer.from(encryptedCard.aad, 'utf8'));
  d.setAuthTag(Buffer.from(encryptedCard.tag, 'base64'));
  const plain = Buffer.concat([d.update(Buffer.from(encryptedCard.ciphertext, 'base64')), d.final()]);
  return JSON.parse(plain.toString('utf8')); // { pan, cvv, expiryMonth, expiryYear }
}

# pip install cryptography
import base64, json
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import padding
from cryptography.hazmat.primitives.ciphers.aead import AESGCM

def decrypt_card(enc: dict, private_key_pem: bytes) -> dict:
    key = serialization.load_pem_private_key(private_key_pem, password=None)
    cek = key.decrypt(base64.b64decode(enc["encryptedKey"]),
                      padding.OAEP(mgf=padding.MGF1(hashes.SHA256()), algorithm=hashes.SHA256(), label=None))
    plain = AESGCM(cek).decrypt(base64.b64decode(enc["iv"]),
                                base64.b64decode(enc["ciphertext"]) + base64.b64decode(enc["tag"]),
                                enc["aad"].encode("utf-8"))
    return json.loads(plain)  # {"pan", "cvv", "expiryMonth", "expiryYear"}

static String decryptCard(Map<String, String> enc, PrivateKey privateKey) throws Exception {
    Base64.Decoder b64 = Base64.getDecoder();
    Cipher rsa = Cipher.getInstance("RSA/ECB/OAEPPadding");
    rsa.init(Cipher.DECRYPT_MODE, privateKey, new OAEPParameterSpec(
            "SHA-256", "MGF1", MGF1ParameterSpec.SHA256, PSource.PSpecified.DEFAULT));
    byte[] cek = rsa.doFinal(b64.decode(enc.get("encryptedKey")));

    Cipher aes = Cipher.getInstance("AES/GCM/NoPadding");
    aes.init(Cipher.DECRYPT_MODE, new SecretKeySpec(cek, "AES"),
            new GCMParameterSpec(128, b64.decode(enc.get("iv"))));
    aes.updateAAD(enc.get("aad").getBytes(StandardCharsets.UTF_8));
    byte[] ct  = b64.decode(enc.get("ciphertext"));
    byte[] tag = b64.decode(enc.get("tag"));
    byte[] sealed = Arrays.copyOf(ct, ct.length + tag.length);   // Java expects ciphertext || tag
    System.arraycopy(tag, 0, sealed, ct.length, tag.length);
    return new String(aes.doFinal(sealed), StandardCharsets.UTF_8); // {"pan":…,"cvv":…,…}
}