public byte[] noPrefixEncrypt(final byte[] plaintext, final byte[] contextInfo)
      throws GeneralSecurityException {
    EciesHkdfSenderKem.KemKey kemKey =
        senderKem.generateKey(
            hkdfHmacAlgo,
            hkdfSalt,
            contextInfo,
            demHelper.getSymmetricKeySizeInBytes(),
            ecPointFormat);
    AeadOrDaead aead = demHelper.getAeadOrDaead(kemKey.getSymmetricKey());
    byte[] ciphertext = aead.encrypt(plaintext, EMPTY_AAD);
    byte[] header = kemKey.getKemBytes();
    return ByteBuffer.allocate(header.length + ciphertext.length)
        .put(header)
        .put(ciphertext)
        .array();
  }
ECIES encryption with HKDF-KEM (key encapsulation mechanism) and AEAD-DEM (data
encapsulation mechanism).

@since 1.0.0
java_src/src/main/java/com/google/crypto/tink/subtle/EciesAeadHkdfHybridEncrypt.java