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Encrypt/Decrypt

Encryption underpins information security — from HTTPS transport to password storage, from API signing to blockchain transactions. This tool supports two categories: <strong>symmetric encryption</strong> (AES, DES) using a single key for both encryption and decryption — fast and suitable for large data; <strong>asymmetric encryption</strong> (RSA) using public/private key pairs — more secure, ideal for key exchange and digital signatures. All cryptographic operations run locally in your browser; keys and plaintext never leave your machine.

Supports multiple AES modes (ECB/CBC/CFB/OFB/CTR), key sizes (128/192/256-bit), and RSA with encryption/decryption and signing/verification at 512/1024/2048/4096-bit key lengths. Ideal for encrypting local config files, learning cryptography concepts, or verifying API signature logic. Note: this tool is for learning and non-production use; do not use it for real sensitive data.

📖 Encryption/Decryption Tool Guide

Symmetric vs Asymmetric Encryption

Encryption falls into two categories: symmetric (same key for encrypt and decrypt — AES, DES) and asymmetric (public key encrypts, private key decrypts — RSA). Symmetric is fast and suited for bulk data. Asymmetric is more secure but slower, typically used for key exchange (encrypt an AES key with RSA) and digital signatures. This tool supports both.

⚙️ Symmetric Encryption

  • Algorithms: AES (256/192/128-bit keys) and DES (56-bit). AES is the NIST standard — globally recognized as secure. DES is included for learning purposes only; its 56-bit key is too short for production use.
  • Modes: ECB, CBC, CFB, OFB, CTR. ECB is insecure (identical plaintext → identical ciphertext). Use CBC for general purposes. CTR is ideal for streaming. CFB/OFB avoid padding. Pick CBC when in doubt.
  • Key generation: Auto-generate a random key or enter your own. AES-256 needs a 32-byte key; AES-128 needs 16 bytes. The tool handles key length matching.
  • Output: Encrypted result in Base64. Hex output also supported.

⚙️ RSA Asymmetric Encryption

  • Key pair generation: 512/1024/2048/4096-bit key lengths. 2048-bit is the current recommended minimum. 4096-bit is more secure but noticeably slower. Keys are displayed in PEM format.
  • Encrypt/Decrypt: Anyone can encrypt with your public key — only you, holding the private key, can decrypt. Perfect for protecting data in transit.
  • Sign/Verify: Sign with private key (create a digital signature), verify with public key (confirm authenticity). Ensures data integrity and origin authenticity — the recipient verifies the data wasn't tampered with and genuinely comes from the claimed sender.

How to Use

  1. Select Symmetric or RSA tab
  2. Symmetric: Choose algorithm (AES/DES) and mode (CBC/CFB/CTR/ECB/OFB), enter or generate a key, toggle encrypt/decrypt, enter text and view results.
  3. RSA encryption: Choose key length (2048 recommended), generate key pair. Encrypt text with the public key; decrypt by pasting the corresponding private key.
  4. RSA signing: Switch to sign mode. Sign text with private key, verify with public key.
  5. Results appear in Base64 with full PEM output. Double-click to copy.

⚠️ Security Notice (Please Read)

This tool is for learning and non-production use. For real sensitive data (passwords, PII, financial data, trade secrets), use production-grade, security-audited cryptographic libraries (OpenSSL, LibreSSL, cloud KMS). Specifically: ECB mode is unsafe (identical plaintext → identical ciphertext); DES\'s 56-bit key is brute-forceable; key management and distribution are harder than encryption itself — any record of a key is a potential leak. All crypto runs client-side — keys and plaintext are not uploaded — but a browser\'s JavaScript runtime is NOT a security boundary.

Command-Line Alternatives

# OpenSSL AES-256-CBC encrypt echo "Hello World" | openssl enc -aes-256-cbc -a -pbkdf2 -pass pass:MyKey # OpenSSL AES decrypt openssl enc -aes-256-cbc -d -a -pbkdf2 -pass pass:MyKey -in encrypted.txt # Generate RSA key pair openssl genpkey -algorithm RSA -out private.pem -pkeyopt rsa_keygen_bits:2048 openssl rsa -pubout -in private.pem -out public.pem # RSA sign and verify openssl dgst -sha256 -sign private.pem -out sig.bin data.txt openssl dgst -sha256 -verify public.pem -signature sig.bin data.txt