get
Derives per-message encryption keys from a conversation key and nonce.
Uses HKDF-Expand to derive ChaCha20 key, ChaCha20 nonce, and HMAC key from the conversation key and message nonce. These keys are used for a single message encryption/decryption.
Return
MessageKeys containing ChaCha20 key (32 bytes), ChaCha20 nonce (12 bytes), and HMAC key (32 bytes)
Parameters
conversation
The 32-byte conversation key
nonce
The 32-byte random nonce (unique per message)
Throws
if conversationKey or nonce are not 32 bytes