Symmetric encryption · ChaCha20

Decrypt ChaCha20-Poly1305 Files

Validate ciphertext and recover plaintext files using ChaCha20-Poly1305. As long as the key, nonce, and AAD match the sender, the tag is verified locally and decryption completes offline.

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Files are processed entirely in this browser tab.

Processed output

Processed files will appear here once encryption or decryption completes.

Secret key

Keys shorter than 32 bytes are zero-padded; longer inputs are truncated.

Nonce

Provide a 12-byte nonce. Never reuse it with the same key.

Additional authenticated data (optional)

ChaCha20-Poly1305 file tips

ChaCha20-Poly1305 keeps large files confidential and tamper-evident. The downloaded ciphertext already includes the authentication tag, so keep it intact when sharing or storing data.

Always pair a unique nonce with each key + file combination. Reusing nonces with ChaCha20 compromises confidentiality and tag verification.

Additional authenticated data (AAD) is not encrypted but is protected by the tag. Use it for filenames, metadata, or protocol headers you want to guard against tampering.