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Tool Factory

Cryptography & Ciphers

Ascon Decryption

Apply Ascon Decrypt with explicit key, format, and algorithm settings. Enter the data and key material, choose the parameters, then review the result.

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Apply Ascon Decrypt with explicit key, format, and algorithm settings. Enter the data and key material, choose the parameters, then review the result.

This tool runs open-source code from CyberChef by GCHQ (Apache License 2.0). See open-source credits.

Ascon Decryption uses Ascon-AEAD128 to process the supplied input. Encryption returns ciphertext with a 128-bit authentication tag; decryption returns plaintext only after tag verification. This record describes decryption or decoding for Ascon Decryption.

Encryption returns ciphertext with a 128-bit authentication tag; decryption returns plaintext only after tag verification. This record describes decryption or decoding for Ascon Decryption. Processing runs in the browser for this catalog category, so the result depends on the supplied bytes and settings. Processing runs in the browser.

Ascon provides confidentiality and integrity for the supplied bytes; it does not provide key exchange or identity authentication.

Instructions

  1. Provide text or data for this tool.
  2. Use a unique nonce for each encryption with the same key. This applies to Ascon Decryption.
  3. Keep associated data unchanged between encryption and decryption. This applies to Ascon Decryption.
  4. Select Hex for binary fixtures and Text for a readable test message. This applies to Ascon Decryption.

Example

Input: Plaintext "Test message"; key "000102030405060708090a0b0c0d0e0f"; nonce "000102030405060708090a0b0c0d0e0f"; associated data "demo". Operation direction: decryption or decoding; algorithm: Ascon Decryption.

Settings: Ascon Decryption: Key: exactly 16 bytes; nonce: exactly 16 bytes. Associated data: optional and authenticated, but not encrypted. Input and output: Text or Hex.

Result: Encryption returns ciphertext with a 128-bit authentication tag; decryption returns plaintext only after tag verification. This record describes decryption or decoding for Ascon Decryption. Processing runs in the browser for this catalog category, so the result depends on the supplied bytes and settings.

Limits

  • Ascon Decryption: The operation rejects keys or nonces with any other length.
  • Ascon Decryption: Nonce reuse with one key can compromise authenticated encryption.
  • Ascon Decryption: The tool does not manage key storage or nonce coordination for another application.

Questions

What key and nonce does this Ascon operation require?

The operation requires a 16-byte key and a 16-byte nonce. Choose the correct representation for each field before checking its length. A nonce is separate from the secret key.

Where is the Ascon authentication tag?

Encryption returns ciphertext with the authentication tag attached. Decryption expects that combined input and the same Associated Data. Changing the key, nonce, data, or tag can cause authentication failure.

Can I reuse one nonce for different Ascon messages?

Use a different nonce for each new encryption under the same key. The tool accepts your supplied nonce; completion does not check your previous usage. Keep the nonce and associated-data convention with the ciphertext.