AES-256-GCM Text Encryption & Decryption

Encrypt and decrypt confidential text locally using authenticated AES-256-GCM and PBKDF2 key derivation (100,000 rounds). 100% in-browser Web Crypto API processing with zero server transmission or storage.

Key is derived locally via PBKDF2-HMAC-SHA256 with a unique 128-bit salt. Never sent to any server.
Input Text / Payload Unicode UTF-8 Ready
Output Result
AES-256-GCM Active
NIST SP 800-38D • Authenticated Encryption with Associated Data (AEAD)
Critical Security Guarantee: Zero-knowledge architecture. All encryption and key derivation take place strictly within your web browser sandbox. Plaintext, secret passwords, derived keys, and ciphertext are never transmitted across the network or logged on any server.

What is AES-256-GCM?

The Advanced Encryption Standard (AES) with Galois/Counter Mode (GCM) is an NIST-approved, authenticated symmetric cipher specified in NIST SP 800-38D.

Unlike unauthenticated modes (such as CBC or legacy ECB, which is fundamentally insecure), AES-GCM operates as an Authenticated Encryption with Associated Data (AEAD) cipher. Along with encrypting your message into unreadable ciphertext, it calculates an authentication tag (128 bits). Upon decryption, the algorithm verifies that the ciphertext has not been modified or corrupted in transit.

Password-Based Key Derivation (PBKDF2-HMAC-SHA256)

Passwords chosen by human beings have significantly lower entropy than the 256 bits required for an AES-256 key. To transform a human password into a strong cryptographic key, this tool uses PBKDF2 (RFC 8018):

  • 128-bit Cryptographic Salt: A fresh 16-byte random salt generated via window.crypto.getRandomValues ensures that two encryptions with identical passwords produce completely distinct keys, defeating rainbow tables.
  • Configurable Iterations: 100,000 computational rounds of HMAC-SHA-256 force an attacker to perform 100,000 hash calculations for every single password candidate in a brute-force attack.
  • 96-bit Initialization Vector (IV): A fresh 12-byte random IV is generated for every message, satisfying GCM's strict uniqueness requirement.

Portable Encrypted Payload Structure

To enable reliable sharing, backup, and cross-device decryption, the tool packages all public cryptographic metadata alongside the ciphertext: 

{
  "v": 1,
  "alg": "AES-256-GCM",
  "kdf": "PBKDF2-SHA256",
  "iter": 100000,
  "salt": "<Base64-16-bytes>",
  "iv": "<Base64-12-bytes>",
  "data": "<Base64-Ciphertext-and-AuthTag>"
}

In Portable String mode, this JSON structure is encoded into a single clean string prefixed with TYENC1. for easy pasting into emails, documents, or messaging apps.

Distinguishing Encryption, Encoding, and Hashing

  • Encryption (AES-256-GCM): Reversible two-way operation. Requires a secret password to decrypt back to plaintext.
  • Encoding (Base64): Reversible two-way representation. Does NOT use a secret key; anyone can decode it instantly.
  • Hashing (SHA-256): One-way irreversible mathematical digest. Cannot be decrypted into the original message.

Frequently Asked Questions

AES-GCM (Galois/Counter Mode) provides both confidentiality (encrypting your plaintext so unauthorized parties cannot read it) and integrity/authenticity (appending a 128-bit authentication tag). If an attacker tampers with even a single bit of the encrypted payload, the Web Crypto API detects the corruption and refuses to decrypt, protecting against ciphertext manipulation attacks.

Reusing an Initialization Vector (IV) with the same key in AES-GCM destroys the cryptographic authenticity of the cipher and can leak plaintext. Furthermore, a fresh 128-bit cryptographic salt ensures that encrypting the same message with the same password twice produces completely different, unlinkable ciphertexts, neutralizing precomputed rainbow-table attacks.

No. Zero-knowledge authenticated encryption has no master keys or backdoors. If you forget or lose the password used to encrypt your text, the encrypted data is mathematically unrecoverable by anyone, including the TechnicalYard team.

Passkeys are converted into high-entropy 256-bit AES keys using PBKDF2 (Password-Based Key Derivation Function 2) combined with HMAC-SHA-256 across 100,000 computational rounds. This deliberately slows down brute-force and dictionary guessing attempts while completing in under 100ms on modern client devices.