Gửi RSA

byte[] der = Base64.getDecoder().decode(PUBLIC_KEY_B64);
PublicKey pub = KeyFactory.getInstance("RSA")
        .generatePublic(new X509EncodedKeySpec(der));

static String encrypt(PublicKey pub, String value) throws Exception {
    Cipher c = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");
    c.init(Cipher.ENCRYPT_MODE, pub, new OAEPParameterSpec(
            "SHA-256", "MGF1", MGF1ParameterSpec.SHA1, PSource.PSpecified.DEFAULT));
    return Base64.getEncoder()
            .encodeToString(c.doFinal(value.getBytes(StandardCharsets.UTF_8)));
}

import base64
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import padding

pub = serialization.load_der_public_key(base64.b64decode(PUBLIC_KEY_B64))

def encrypt(value: str) -> str:
    ct = pub.encrypt(
        value.encode("utf-8"),
        padding.OAEP(
            mgf=padding.MGF1(algorithm=hashes.SHA1()),
            algorithm=hashes.SHA256(),
            label=None,
        ),
    )
    return base64.b64encode(ct).decode("ascii")

use phpseclib3\Crypt\PublicKeyLoader;
use phpseclib3\Crypt\RSA;

$pub = PublicKeyLoader::load(base64_decode(PUBLIC_KEY_B64))
        ->withPadding(RSA::ENCRYPTION_OAEP)
        ->withHash('sha256')
        ->withMGFHash('sha1');

function encryptRsa($pub, string $value): string {
    return base64_encode($pub->encrypt($value));
}

{ echo "-----BEGIN PUBLIC KEY-----"
  fold -w 64 <<< "$PUBLIC_KEY_B64"
  echo "-----END PUBLIC KEY-----"; } > oa.pem

printf '%s' "$value" \
  | openssl pkeyutl -encrypt -pubin -inkey oa.pem \
      -pkeyopt rsa_padding_mode:oaep \
      -pkeyopt rsa_oaep_md:sha256 \
      -pkeyopt rsa_mgf1_md:sha1 \
  | openssl base64 -A