OffCrypt is an encryption and messaging application for Android devices that works in a PGP‑style: it uses public‑key cryptography so messages can be encrypted with a recipient's public key and decrypted only with their private key. The app combines multiple modern cryptographic algorithms and offers an array of security features to keep your communications private. Built in Kotlin, OffCrypt operates fully offline — no Internet permission is required.

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                            PGP-Style Public Key Cryptography
                        

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                            Open-source
                        

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                            Fully Offline application
                        

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                            File Encryption
                        

📱 Screenshots

Explore the app interface • 👈 Scroll horizontally

OffCrypt main interface displaying encryption controls and secure messaging dashboard

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Android security app encryption page showing RSA key generation and PGP messaging settings

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Security settings view with AES-256 encryption and perfect forward secrecy indicators

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OffCrypt application settings panel with cryptographic configuration options

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🔐 Features

Explore all 36+ security features • 👆 Swipe or use arrows

🔐 Cryptography

Encryption algorithms

1/7

🔑 RSA-2048 — Asymmetric public key cryptography
🔑 RSA-4096 — Asymmetric public key cryptography
🛡️ AES-256-GCM — Symmetric encryption with authentication
🔐 PBKDF2 — Password derivation (100,000 iterations)
🏷️ HmacSHA256 — Ensures message integrity
⚡ SHA-256 — Cryptographic hash function for keys
🎲 SecureRandom — Cryptographically secure RNG

✨ Advanced Security

Next-generation protection features

2/7

✍️ Digital signature — Ensures message authenticity
🔄 Perfect Forward Secrecy (PFS) — ECDH key exchange
⏰ Expiring messages — Automatic expiration (1h-1y)
🔥 Burn After Reading — Automatic message destruction
🔒 Version Byte — Automatic algorithm detection

🛡️ Attack Protection

Defense against sophisticated threats

3/7

⚖️ Constant-time HMAC — Prevents timing attacks
🔍 Data validation — Verification of cryptographic structures
❌ Replay attack protection — GCM nonce and metadata
🔐 Side-channel attack prevention — Secure implementations
🛡️ MITM attack protection — Certificate pinning

🧹 Memory Safety

Complete sensitive data protection

4/7

🧹 Sensitive data scrubbing — 3x overwrite + zero out
💾 Char/ByteArray wiping — UTF-8 and memory clearing
♻️ Aggressive Garbage Collection — 3x memory cleanup
📋 Log buffer clearing — Android logcat cleanup
🔄 String pool cleanup — JVM string cache wiping

🖥️ UI Security

User interface protection

5/7

📋 Secure Clipboard — Automatic clearing (60s)
🔒 Lifecycle cleanup — Data destroyed on app close
⏸️ Background cleanup — Data cleared when backgrounded
🚨 Burn dialog — Warning for self-destructing messages
👁️ Screenshot protection — Secure window flags

⚙️ Features

Advanced enhancements & storage

6/7

🧠 RSA OAEP + SHA-256 + MGF1 — Modern key encryption
📜 RSA signature with SHA-512 — Maximum authenticity
📦 Version Byte detection — Algorithm auto-selection
🔁 Metadata fallback — Legacy format support
📤 Encrypted file export — AES-256-GCM format
🔒 Encrypted RSA keystore — Internal AES storage
📛 AndroidOpenSSL fallback — Multi-engine support

🛡️ Complete Security Package

36+ Active Security Features

7/7

🔐 Cryptography — RSA-4096 + AES-256-GCM
🛡️ Multi-layer attack protection — Timing, replay & validation
🧹 Complete memory safety — 3x scrubbing & GC
🔒 Advanced UI security — Lifecycle & clipboard protection
⚙️ Professional features — Encrypted storage & validation
🗑️ Nuclear reset option — Complete data destruction

🚀 Download now

⬇️ Download OffCrypt (.apk) 💻 View on GitHub

Free • No ads • Open source • GPL-3.0 License

🔐 RSA-4096 🛡️ AES-256-GCM 🔥 Burn After Reading ⚡ Perfect Forward Secrecy

☕ Support Development

Thank you for exploring OffCrypt! If you like the app or find it useful, please consider supporting the project via the Ko‑fi link above

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