What is Text Decryption?

Text decryption reverses the encryption process, recovering the original plaintext from ciphertext using the correct key and algorithm. The supported algorithms are: AES-GCM (most secure, authenticated encryption — recommended), AES-CBC (common but requires padding), AES-CTR (stream cipher mode), and RSA-OAEP (asymmetric encryption using a key pair). Each algorithm has different properties for security, use cases, and key requirements. AES-GCM includes authentication — it detects if the ciphertext was tampered with. AES-CBC and CTR don't provide this protection on their own.

Supported Algorithms:

Symmetric Decryption (AES):

• AES-GCM (Recommended): Provides authenticated encryption with associated data (AEAD). Most secure for general use.
• AES-CBC: Traditional block cipher mode. Requires padding.
• AES-CTR: Counter mode. Converts block cipher to stream cipher.

Asymmetric Decryption (RSA):

• RSA-OAEP: Uses private key for decryption. Requires the corresponding private key to the public key used for encryption.

Expected Input Format:

For AES algorithms: JSON with base64-encoded components

{"iv": "base64_encoded_iv", "data": "base64_encoded_ciphertext"}

Also supports legacy hex format:

{"iv": "hex_encoded_iv", "data": "hex_encoded_ciphertext"}

For RSA: Base64-encoded ciphertext only

base64_encoded_ciphertext

How to Use the Text Decrypt Tool

1. Paste the encrypted ciphertext (usually Base64-encoded) into the input field.

2. Select the same algorithm that was used for encryption.

3. Enter the decryption key — the same secret key used during encryption.

4. For RSA-OAEP, paste the private key in PEM format.

5. Click Decrypt — the original plaintext is revealed in the output.

Additional Tips:

• For AES: Use the same secret key that was used for encryption
• For RSA: You need the private key corresponding to the public key used for encryption
• Automatic format detection: The tool automatically detects base64 or hex encoding
• Error handling: If decryption fails, check that you're using the correct algorithm and key

Security Notes

This tool uses the browser's native Web Crypto API for secure decryption. All decryption happens locally in your browser - no data or keys are ever sent to external servers. Make sure you're using the correct algorithm and key that match the encryption method used. The tool supports both base64 (standard) and hex (legacy) encoding formats for AES encrypted data.

Important Notes:

• All decryption happens locally in your browser using the Web Crypto API
• Your private keys and secrets never leave your browser
• For RSA decryption, you decrypt with a private key; the data was encrypted with the corresponding public key
• Keep your private keys and secret keys secure - they are the only way to decrypt your data
• The tool supports both base64 (standard) and hex (legacy) encoding formats

This text decryption tool uses the Web Crypto API built into your browser — decryption happens locally and your data and keys are never transmitted. Supports AES-GCM, AES-CBC, AES-CTR, and RSA-OAEP. Paired with the Text Encryption tool for symmetric encryption/decryption.

Frequently Asked Questions

Why does decryption fail even with the correct key? Common causes: wrong algorithm selected (must match what was used to encrypt), corrupted or truncated ciphertext, wrong key (even one character off produces a different key), or the IV/nonce was not correctly included with the ciphertext. AES-GCM additionally fails if the authentication tag was tampered with.

What is the difference between AES-GCM and AES-CBC? AES-GCM (Galois/Counter Mode) is an authenticated encryption mode — it encrypts and authenticates simultaneously, detecting any tampering. AES-CBC (Cipher Block Chaining) is an older mode that only encrypts without authentication — you need a separate MAC to detect tampering. AES-GCM is the modern recommended choice.

Can I decrypt data encrypted by other tools? Only if the other tool uses the same algorithm, key format, and IV/nonce encoding. Encryption implementations vary in how they encode the key, salt, IV, and output. This tool uses standard Web Crypto API formats, so compatibility with other implementations depends on matching all parameters.

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