Senior Secure Mobile Engineer (iOS / Android)

About the Role

We are looking for a Senior Secure Mobile Engineer (iOS / Android) to join a Client’s team building a high-security, Zero-Knowledge, privacy-first mobile product.

This role is security-critical: the mobile app is responsible for encryption, secure key management, encrypted local storage, and encrypted voice/video communication. You will work on protecting sensitive data on-device and in transit, even in adversarial environments.

This is not a typical mobile UI role — we are looking for an engineer with strong mobile security, applied cryptography, and secure communications expertise.

Location: Remote
Cooperation Type: Full-time, long-term
Experience Level: Senior
Start: ASAP

Responsibilities

• Design and develop a security-first mobile client (iOS / Android)
• Implement end-to-end encryption, secure key generation, and key lifecycle management
• Build and maintain encrypted local storage (SQLCipher / encrypted SQLite)
• Integrate hardware-backed security (iOS Keychain, Android Keystore, Secure Enclave)
• Secure voice and video traffic using encrypted protocols (WebRTC, SRTP, or similar)
• Protect sensitive data at rest and in transit using modern cryptographic standards
• Apply memory hygiene practices to prevent sensitive data leakage
• Implement certificate pinning and defense against MITM attacks
• Design and enforce privacy-first and Zero-Knowledge client-side security principles
• Conduct threat modeling, security reviews, and risk assessments
• Collaborate with backend and security teams on end-to-end encrypted workflows
• Write clean, testable, and security-auditable code

Requirements

• 5+ years of mobile development experience (iOS / Android)
• 3+ years of experience in mobile security / secure data handling
• Strong understanding of applied cryptography and encryption principles
• Experience implementing end-to-end encryption and secure key management
• Strong experience with encrypted local storage (SQLCipher / encrypted SQLite)
• Experience with iOS Keychain and / or Android Keystore
• Experience securing voice and video traffic (WebRTC, encrypted media pipelines, or similar)
• Experience implementing certificate pinning and secure networking
• Understanding of memory hygiene, secure sessions, and data isolation
• Proficiency in Swift, Kotlin, Objective-C, or Java
• Experience working on security-critical or privacy-first systems
• Ability to work independently in high-responsibility security environments
• English: Upper-Intermediate (B2) or higher

Nice to Have

• Experience with Signal Protocol (X3DH, Double Ratchet) or MLS
• Experience with Zero-Knowledge systems
• Experience with Tor / Orbot / anonymous networking
• Experience with secure real-time communications hardening (WebRTC)
• Experience with mobile threat modeling or reverse engineering
• Experience with on-device AI / offline inference
• Experience with advanced mobile OS security or low-level performance optimization

What We Offer

• Competitive compensation according to your experience (gross system)
• Fully remote work and long-term cooperation
• Opportunity to work on a high-security, privacy-first product
• Direct impact on core encryption and mobile security architecture
• Fast hiring process and quick start
• Strong engineering culture focused on security, ownership, and quality

What happens after you apply

• Quick CV review
• Short recruiter call
• Technical interview with LITSLINK team
• Fast decision & offer