Letro Architecture:
A Deep Dive
Letro is a next-generation formal communication platform built for mobile and desktop environments, leveraging robust end-to-end encryption and trustless infrastructures.
Our mission is to enable institutions and individuals alike to establish secure, direct communication without compromising on data ownership, authenticity, or privacy.
End-to-End Communication
End-to-end (E2E) communication is at the core of Letro’s approach. It ensures that only the sender and intended recipient(s) can access the content of messages or shared data. No third parties—including service providers—can intercept or decrypt this information.
How It Works
Encryption
Letro encrypts every message or file at the sender’s device before it even leaves the application.
Transmission
Ciphertext, or encrypted data, is transmitted securely over communication channels like the internet or other networks.
Decryption
Letro Decrypts every message or file at the recipient’s device before.
Authentication
Decrypted data is verified to ensure its integrity and authenticity. This step might involve verifying the sender’s digital signature to confirm that no one tampered with the data during transmission.
Why It Matters
The Signal Protocol
Foundation of Security
Letro is built on top of the widely acclaimed Signal protocol. Renowned for its strong cryptographic properties, Signal offers forward secrecy, deniability, and robust key management—features that are vital for secure communications in modern digital environments.
By adopting Signal’s proven cryptography, Letro significantly reduces risks commonly associated with proprietary encryption methods.
Key Benefits
End-to-End Encryption
State of the Art E2E cryptography built for maintaning security and privacy.
Forward & Backward Secrecy
Each session key is ephemeral, meaning past conversations can’t be decrypted if a single key is compromised.
Post-Quantum Encryption
Kyber, a secure Key-Encapsulation Mechanism (KEM), is purpose-built to resist quantum attacks.
Double-Ratchet Algorithm
The Double Ratchet algorithm is designed to provide security against an attacker who records encrypted messages and then compromises the sender or receiver at a later time.
Authentication
Signal’s design allows for verifiable message sending while preventing later repudiation or false claims of authorship.
Group Messaging
Signal service has no record of your group memberships, group titles, group avatars, or group attributes.
Trustless Approach
A “trustless” approach removes the necessity to rely on any single authoritative intermediary for security or data integrity. Instead, the system’s architecture ensures all parties can independently verify the accuracy and authenticity of information.
Data Ownership by the User
User-Controlled Keys
Ownership begins with cryptographic keys. Each user holds their unique private keys, retaining the ultimate authority over access to their data.
No Central Custodian
Letro acts only as a conduit; we do not store or manage your private keys, making it impossible for us—or anyone else—to decrypt your communications.
Data Provenance
Immutable Audit Trails
Each communication event has an associated cryptographic proof, establishing a verifiable record of origin and history.
No Central Custodian
Regardless of where a user accesses Letro (mobile, desktop, or web), the underlying cryptographic proofs remain consistent and universally verifiable.
Data Authenticity & Integrity
Cryptographic Signatures
Every message and file is signed, ensuring that content cannot be tampered with without detection.
Tamper Evident
If any alterations do occur, they’re instantly flagged, preserving the chain of trust for all parties in a conversation or transaction.
Enterprise-Level Architecture For Access Control
Enterprises need communication solutions that handle organizational hierarchies, access controls, and custom workflows—all without compromising security. Letro meets these demands by integrating robust end-to-end encryption with features tailored for complex organizational structures.
1. Organization Hierarchy
User-Controlled Keys – Ownership begins with cryptographic keys. Each user holds their unique private keys, retaining the ultimate authority over access to their data.No Central Custodian – Letro acts only as a conduit; we do not store or manage your private keys, making it impossible for us—or anyone else—to decrypt your communications.
2. Access Levels
Role-based permissions let managers control who can view or modify sensitive communications. By enforcing read/write privileges, only authorized personnel have access to confidential information, preserving both security and accountability.
3. Custom Workflows
Letro supports automated approval chains, escalation paths, and audit trails. Even under the most complex workflows, communications remain encrypted end-to-end, preventing any unintended data exposure. add. templates
4. Seamless E2E Integration
Despite these enterprise-grade features, Letro’s architecture is anchored in device-level encryption, guaranteeing that all data is safeguarded and tamper-proof from creation to completion.