ngtcp2_conn_install_vneg_initial_key
====================================

Synopsis
--------

*#include <ngtcp2/ngtcp2.h>*

.. function:: int ngtcp2_conn_install_vneg_initial_key( ngtcp2_conn *conn, uint32_t version, const ngtcp2_crypto_aead_ctx *rx_aead_ctx, const uint8_t *rx_iv, const ngtcp2_crypto_cipher_ctx *rx_hp_ctx, const ngtcp2_crypto_aead_ctx *tx_aead_ctx, const uint8_t *tx_iv, const ngtcp2_crypto_cipher_ctx *tx_hp_ctx, size_t ivlen)

    
    `ngtcp2_conn_install_vneg_initial_key` installs packet protection
    keying materials for Initial packets on compatible version
    negotiation for *version*.  *rx_aead_ctx* is AEAD cipher context
    object, and must be initialized with a decryption key.  *rx_iv* is
    IV of length *rx_ivlen* for decryption.  *rx_hp_ctx* is a packet
    header protection cipher context object for decryption.  Similarly,
    *tx_aead_ctx*, *tx_iv* and *tx_hp_ctx* are for encrypting outgoing
    packets, and are the same length with the decryption counterpart.
    If they have already been set, they are overwritten.
    
    *ivlen* must be the minimum length of AEAD nonce, or 8 bytes if
    that is larger.
    
    If this function succeeds, *conn* takes ownership of *rx_aead_ctx*,
    *rx_hp_ctx*, *tx_aead_ctx*, and *tx_hp_ctx*.
    :member:`ngtcp2_callbacks.delete_crypto_aead_ctx` and
    :member:`ngtcp2_callbacks.delete_crypto_cipher_ctx` will be called
    to delete these objects when they are no longer used.  If this
    function fails, the caller is responsible to delete them.
    
    This function returns 0 if it succeeds, or one of the following
    negative error codes:
    
    :macro:`NGTCP2_ERR_NOMEM`
        Out of memory.