Cythrix

Advanced end-to-end encryption for secure communication

What is Cythrix?

Cythrix is an advanced encryption tool that combines asymmetric and symmetric cryptography to provide maximum security for sensitive messages. The tool implements industry-standard cryptographic algorithms and offers end-to-end encryption with digital signatures for authentication.

With Cythrix, you can 'obscure' (encrypt) and 'expose' (decrypt) messages where every step is cryptographically secured. The system ensures not only the confidentiality of your messages, but also their integrity and authenticity.

Why do you need Cythrix?

🔒 Confidentiality

Your messages are fully encrypted and can only be read by the intended recipient.

✍️ Authenticity

Digital signatures guarantee that the message actually came from the sender.

🛡️ Integrity

Any modification to the message is detected via cryptographic hashing.

⏱️ Anti-Replay

Timestamps prevent old messages from being reused in replay attacks.

Ideal for sensitive communication, business documents, or situations where you want absolute certainty about the security and origin of a message.

How does Cythrix work?

Obscure (Encryption)

When you encrypt a message, Cythrix goes through the following steps:

  1. A timestamp is added to the original message for replay-attack prevention
  2. A unique symmetric key (AESGCM AES-256) is generated
  3. The message is encrypted with this symmetric key
  4. A SHA-512 hash of the original message is calculated
  5. The hash is digitally signed with your private key (RSA-4096)
  6. The symmetric key is encrypted with the recipient's public key (RSA-4096 with OAEP)
  7. All components are combined into a structured format

Expose (Decryption)

When decrypting, the process is reversed:

  1. The obscured message is split into its components
  2. The symmetric key is decrypted with the recipient's private key
  3. The message is decrypted with the symmetric key
  4. The digital signature is verified with the sender's public key
  5. The timestamp is checked and displayed
  6. Authenticity is confirmed or rejected
⚠️ Important: The combination of asymmetric and symmetric encryption ensures that large messages can be encrypted efficiently, while asymmetric cryptography provides secure key exchange.

Technical Specifications

Asymmetric Algorithm RSA
RSA Key Size 4096 bits
RSA Padding OAEP with SHA-512 and MGF1
Symmetric Algorithm AESGCM (AES-256 in GCM mode with HMAC)
Hash Algorithm SHA-512
Signature Padding PSS with SHA-512 and MGF1
Private Key Protection PKCS8 with password encryption (BestAvailableEncryption)
Encoding Base64 for transport
Timestamp Format Unix timestamp (seconds since epoch)

Message Structure

An obscured message has the following structure:

==Cythrix==[encrypted_symmetric_key]==Cythrix==[encrypted_message]==Cythrix==[signature]==Cythrix==

All components are Base64-encoded for safe transport.

How to use Cythrix?

1

Download Cythrix

Download the tool here, extract the ZIP, don't change any file location and keep them in the same folder. Upon opening, you will receive a warning, this is because we don't pay for a Code Signing Certificate. Just expand and press continue anyway.

2

Generate Keys

When starting Cythrix, you can generate new key pairs. Enter 'G' when prompted and choose a strong password for your private key. Keep your private key safe and secret, and share your public key with people who want to send you encrypted messages.

3

Load Keys

Enter your own private key and its corresponding password. Then enter the public key of the person you want to communicate with (for obscure) or from whom you want to read a message (for expose).

4

Obscure a Message

Type or paste your message in the text field. Click the "Obscure" button. The encrypted message appears in a new window. Copy this obscured message and send it to the recipient through any channel (email, chat, etc.).

5

Expose a Message

Paste the received obscured message in the text field. Click the "Expose" button. The original message is shown along with the authentication status and timestamp. Check that "Authoritive: True" is displayed for a valid message.

🔐 Security Tips:
  • Always keep your private key safe and make backups
  • Use a strong password for your private key
  • Always verify authenticity (Authoritive status) when exposing
  • Check the timestamp to detect replay attacks
  • Exchange public keys through a trusted channel