ngtcp2_conn_install_initial_key
===============================

Synopsis
--------

*#include <ngtcp2/ngtcp2.h>*

.. function:: int ngtcp2_conn_install_initial_key( ngtcp2_conn *conn, 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_initial_key` installs packet protection keying
    materials for Initial packets.  *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.
    
    After receiving Retry packet, a Destination Connection ID that
    client sends in Initial packet most likely changes.  In that case,
    client application must generate these keying materials again based
    on new Destination Connection ID, and install them again with this
    function.
    
    This function returns 0 if it succeeds, or one of the following
    negative error codes:
    
    :macro:`NGTCP2_ERR_NOMEM`
        Out of memory.