Struct EncryptedChannel 

pub struct EncryptedChannel {
    pub peer_id: String,
    /* private fields */
}

Encrypted communication channel using ChaCha20-Poly1305 AEAD

Security Properties

• Confidentiality: ChaCha20 stream cipher (IND-CPA)
• Integrity: Poly1305 MAC (SUF-CMA)
• AEAD: Combined mode (IND-CCA2)
• Nonce: 96-bit random + 32-bit counter (unique per message)

Example

let channel = EncryptedChannel::new(peer_id, shared_secret);
let ciphertext = channel.encrypt(b"secret message")?;
let plaintext = channel.decrypt(&ciphertext)?;

Fields

peer_id: String

Peer identifier

Implementations

impl EncryptedChannel

pub fn new(peer_id: String, shared_secret: SharedSecret) -> Self

Create a new encrypted channel from a shared secret

Arguments

• peer_id - Identifier for the peer (for auditing/logging)
• shared_secret - Shared secret from Kyber KEM

Security

Keys are derived using HKDF-SHA256 with domain separation.

pub fn encrypt(&self, plaintext: &[u8]) -> Result<Vec<u8>>

Encrypt a message using ChaCha20-Poly1305

Arguments

• plaintext - Message to encrypt

Returns

Ciphertext format: [nonce: 12 bytes][ciphertext][tag: 16 bytes]

Errors

Returns CryptoError if encryption fails (should never happen).

Security

• Unique nonce per message (96-bit random + 32-bit counter)
• Authenticated encryption (modify ciphertext = detection)
• Quantum resistance: 128-bit security (Grover bound)

pub fn decrypt(&self, ciphertext: &[u8]) -> Result<Vec<u8>>

Decrypt a message using ChaCha20-Poly1305

Arguments

• ciphertext - Encrypted message (format: [nonce: 12][ciphertext][tag: 16])

Returns

Decrypted plaintext

Errors

Returns CryptoError if:

• Ciphertext is too short (< 28 bytes)
• Authentication tag verification fails (tampering detected)
• Decryption fails

Security

• Constant-time: Timing independent of plaintext content
• Tamper-evident: Any modification causes authentication failure

pub fn sign(&self, message: &[u8]) -> Vec<u8>

Sign a message with HMAC-SHA256

Arguments

• message - Message to authenticate

Returns

32-byte HMAC tag

Security

• PRF security: tag reveals nothing about key
• Quantum resistance: 128-bit security (Grover)

Note

If using encrypt(), signatures are redundant (Poly1305 provides authentication). Use this for non-encrypted authenticated messages.

pub fn verify(&self, message: &[u8], signature: &[u8]) -> bool

Verify a message signature using constant-time comparison

Arguments

• message - Original message
• signature - HMAC tag to verify

Returns

true if signature is valid, false otherwise

Security

• Constant-time: Execution time independent of signature validity
• Timing-attack resistant: No early termination on mismatch

Critical Security Property

This function MUST use constant-time comparison to prevent timing side-channels.

Trait Implementations

impl Clone for EncryptedChannel

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for EncryptedChannel

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for EncryptedChannel

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for EncryptedChannel

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.