Function decrypt 

pub fn decrypt(
    key: &SessionKey,
    nonce: &[u8; 24],
    aad: &[u8],
    ciphertext: &[u8],
) -> Result<Vec<u8>, CryptoError>

Available on crate feature crypto only.

Decrypt ciphertext using XChaCha20-Poly1305.

Arguments

• key - 32-byte session key
• nonce - 24-byte nonce (constructed from epoch, direction, counter)
• aad - Additional authenticated data
• ciphertext - Ciphertext with appended 16-byte Poly1305 tag

Returns

Decrypted plaintext, or error if authentication fails