target = "https://www.rfc-editor.org/rfc/rfc9001#section-6.2"

# 6.2.  Responding to a Key Update
#
# A peer is permitted to initiate a key update after receiving an
# acknowledgment of a packet in the current key phase.  An endpoint
# detects a key update when processing a packet with a key phase that
# differs from the value used to protect the last packet it sent.  To
# process this packet, the endpoint uses the next packet protection key
# and IV.  See Section 6.3 for considerations about generating these
# keys.
# 
# If a packet is successfully processed using the next key and IV, then
# the peer has initiated a key update.  The endpoint MUST update its
# send keys to the corresponding key phase in response, as described in
# Section 6.1.  Sending keys MUST be updated before sending an
# acknowledgment for the packet that was received with updated keys.
# By acknowledging the packet that triggered the key update in a packet
# protected with the updated keys, the endpoint signals that the key
# update is complete.
# 
# An endpoint can defer sending the packet or acknowledgment according
# to its normal packet sending behavior; it is not necessary to
# immediately generate a packet in response to a key update.  The next
# packet sent by the endpoint will use the updated keys.  The next
# packet that contains an acknowledgment will cause the key update to
# be completed.  If an endpoint detects a second update before it has
# sent any packets with updated keys containing an acknowledgment for
# the packet that initiated the key update, it indicates that its peer
# has updated keys twice without awaiting confirmation.  An endpoint
# MAY treat such consecutive key updates as a connection error of type
# KEY_UPDATE_ERROR.
# 
# An endpoint that receives an acknowledgment that is carried in a
# packet protected with old keys where any acknowledged packet was
# protected with newer keys MAY treat that as a connection error of
# type KEY_UPDATE_ERROR.  This indicates that a peer has received and
# acknowledged a packet that initiates a key update, but has not
# updated keys in response.

[[spec]]
level = "MUST"
quote = '''
The endpoint MUST update its
send keys to the corresponding key phase in response, as described in
Section 6.1.
'''

[[spec]]
level = "MUST"
quote = '''
Sending keys MUST be updated before sending an
acknowledgment for the packet that was received with updated keys.
'''

[[spec]]
level = "MAY"
quote = '''
An endpoint
MAY treat such consecutive key updates as a connection error of type
KEY_UPDATE_ERROR.
'''

[[spec]]
level = "MAY"
quote = '''
An endpoint that receives an acknowledgment that is carried in a
packet protected with old keys where any acknowledged packet was
protected with newer keys MAY treat that as a connection error of
type KEY_UPDATE_ERROR.
'''