algochat 0.2.1

Rust implementation of the AlgoChat protocol for encrypted messaging on Algorand
Documentation 
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//! Type definitions and protocol constants for AlgoChat.

use thiserror::Error;

/// Protocol version byte.
pub const PROTOCOL_VERSION: u8 = 0x01;

/// Protocol ID byte.
pub const PROTOCOL_ID: u8 = 0x01;

/// Size of the envelope header in bytes.
pub const HEADER_SIZE: usize = 126;

/// Size of the authentication tag in bytes.
pub const TAG_SIZE: usize = 16;

/// Size of the encrypted sender key (32-byte key + 16-byte tag).
pub const ENCRYPTED_SENDER_KEY_SIZE: usize = 48;

/// Maximum payload size in bytes.
pub const MAX_PAYLOAD_SIZE: usize = 882;

/// Size of the nonce in bytes.
pub const NONCE_SIZE: usize = 12;

/// Size of a public key in bytes.
pub const PUBLIC_KEY_SIZE: usize = 32;

/// Key derivation salt.
pub const KEY_DERIVATION_SALT: &[u8] = b"AlgoChat-v1-encryption";

/// Key derivation info.
pub const KEY_DERIVATION_INFO: &[u8] = b"x25519-key";

/// Encryption info prefix for message encryption.
pub const ENCRYPTION_INFO_PREFIX: &[u8] = b"AlgoChatV1";

/// Sender key info prefix for bidirectional decryption.
pub const SENDER_KEY_INFO_PREFIX: &[u8] = b"AlgoChatV1-SenderKey";

/// Decrypted message content.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct DecryptedContent {
    /// The message text.
    pub text: String,
    /// Transaction ID this message replies to, if any.
    pub reply_to_id: Option<String>,
    /// Preview of the replied message, if any.
    pub reply_to_preview: Option<String>,
}

impl DecryptedContent {
    /// Create a new DecryptedContent with just text.
    pub fn new(text: impl Into<String>) -> Self {
        Self {
            text: text.into(),
            reply_to_id: None,
            reply_to_preview: None,
        }
    }
}

/// Errors that can occur during AlgoChat operations.
#[derive(Error, Debug)]
pub enum AlgoChatError {
    // Encryption Errors
    /// Invalid seed length.
    #[error("Invalid seed length: expected 32 bytes, got {0}")]
    InvalidSeedLength(usize),

    /// Message too large.
    #[error("Message too large: {0} bytes (max {MAX_PAYLOAD_SIZE})")]
    MessageTooLarge(usize),

    /// Encryption failed.
    #[error("Encryption failed: {0}")]
    EncryptionError(String),

    /// Decryption failed.
    #[error("Decryption failed: {0}")]
    DecryptionError(String),

    /// Failed to encode message as UTF-8.
    #[error("Encoding failed: {0}")]
    EncodingError(String),

    /// Failed to generate secure random bytes.
    #[error("Random generation failed")]
    RandomGenerationFailed,

    /// Invalid public key format.
    #[error("Invalid public key: {0}")]
    InvalidPublicKey(String),

    /// Could not derive encryption keys.
    #[error("Key derivation failed: {0}")]
    KeyDerivationFailed(String),

    /// Signature verification failed.
    #[error("Invalid signature: {0}")]
    InvalidSignature(String),

    // Envelope Errors
    /// Invalid envelope data.
    #[error("Invalid envelope: {0}")]
    InvalidEnvelope(String),

    /// Unknown protocol version.
    #[error("Unknown protocol version: {0}")]
    UnknownVersion(u8),

    /// Unknown protocol ID.
    #[error("Unknown protocol ID: {0}")]
    UnknownProtocolId(u8),

    // Network Errors
    /// Indexer is not configured.
    #[error("Indexer not configured")]
    IndexerNotConfigured,

    /// Could not find public key for address.
    #[error("Public key not found for address: {0}")]
    PublicKeyNotFound(String),

    /// Invalid recipient address.
    #[error("Invalid recipient: {0}")]
    InvalidRecipient(String),

    // Transaction Errors
    /// Transaction failed.
    #[error("Transaction failed: {0}")]
    TransactionFailed(String),

    /// Insufficient balance.
    #[error("Insufficient balance: need {required} microAlgos, have {available}")]
    InsufficientBalance { required: u64, available: u64 },

    // Storage Errors
    /// Key not found in storage.
    #[error("Key not found for address: {0}")]
    KeyNotFound(String),

    /// Storage operation failed.
    #[error("Storage failed: {0}")]
    StorageFailed(String),

    // Queue Errors
    /// Message not found in queue.
    #[error("Message not found: {0}")]
    MessageNotFound(String),
}

pub type Result<T> = std::result::Result<T, AlgoChatError>;

/// Size of an Ed25519 signature in bytes.
pub const SIGNATURE_SIZE: usize = 64;

/// Minimum payment amount in microAlgos (0.001 ALGO).
pub const MINIMUM_PAYMENT: u64 = 1000;