🔐 PGP Encryption & Decryption

🔐 About This PGP Tool & Cryptographic Methodology

This online PGP encryption and decryption tool implements the OpenPGP standard (RFC 4880) using industry-standard Java cryptography libraries (Bouncy Castle). All cryptographic operations are performed server-side using RSA public-key cryptography with configurable key sizes (1024-4096 bits). Messages are encrypted using a hybrid approach: symmetric encryption (AES/3DES) for the message body and RSA public-key encryption for the session key.

How PGP Encryption Works:

1. Key Generation: RSA keypair (public + private) is generated using cryptographically secure random number generation
2. Encryption: Message is compressed (ZIP), encrypted with a symmetric key (AES-256), then the symmetric key is encrypted with recipient's RSA public key
3. Decryption: Private key decrypts the session key, which then decrypts the message body. Passphrase protects the private key using symmetric encryption
4. Security Model: Even if the encrypted message is intercepted, only the holder of the private key (and passphrase) can decrypt it

🎓 Technical Implementation Details

Cryptographic Library: Bouncy Castle (org.bouncycastle.openpgp) - industry-standard, peer-reviewed Java cryptography provider

• Key Algorithm: RSA (Rivest-Shamir-Adleman) - asymmetric encryption
• Symmetric Cipher: AES-256 or 3DES for message encryption
• Hash Algorithm: SHA-256 for integrity verification
• Compression: ZIP compression before encryption (reduces ciphertext size)
• Armor Format: ASCII-armored output (Base64 encoding with checksums)
• Key Protection: Private keys encrypted with passphrase using S2K (String-to-Key) with iteration count

⚠️ Security Best Practices

• Key Size: Use 2048-bit or 4096-bit RSA keys for long-term security
• Strong Passphrases: Protect private keys with 20+ character passphrases (use passphrase generator)
• Key Storage: Store private keys in secure, offline locations (encrypted USB drives, hardware tokens)
• Key Rotation: Rotate keys every 2-3 years or immediately if compromised
• Verify Recipients: Always verify public key fingerprints through a separate channel before encrypting sensitive data
• Backup Keys: Securely backup private keys - if lost, encrypted messages are unrecoverable

📚 Authoritative Sources & Standards

• RFC 4880 - OpenPGP Message Format (IETF Standard)
• OpenPGP.org - Official OpenPGP Working Group
• Bouncy Castle Crypto APIs (Legion of the Bouncy Castle Inc.)
• NIST SP 800-57 - Key Management Guidelines
• RFC 3447 - RSA Cryptography Specifications
• GNU Privacy Guard (GPG) Documentation

🔍 Common Use Cases

• Email Encryption: Encrypt sensitive emails end-to-end (E2EE)
• File Encryption: Secure confidential documents before cloud storage or transmission
• API Credentials: Share API keys, passwords, or tokens securely
• Compliance: Meet GDPR, HIPAA, PCI-DSS encryption requirements
• Secure Messaging: Send encrypted messages without trusting intermediaries
• Code Signing: Verify authenticity of software releases (with PGP signatures)

Related Topics: PGP encryption, OpenPGP, GPG, RSA encryption, public key cryptography, end-to-end encryption, email encryption, secure file transfer, digital signatures, key management, RFC 4880, Bouncy Castle, AES encryption, asymmetric cryptography