CryptoSym v1.8, January 2022
http://sectools.free.fr

CryptoSym is a tool for understanding secret key cryptography,
and particularly illustrate the relationship between key and passphrase.

It's obviously not the best way of protecting everyday data ... (use PGP ou GnuPG instead).

how to use it :
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1) choose a cipher,
2) choose a mode of operation,
3) AEAD only (GCM or CCM modes) : enter the tag (for decryption) and/or addional authenticated data,
4) generate a key and an initialisation vector,
5) enter clear or cipher text and select the appropriate encoding (text, hexa or base64),
6) then click on encrypt, decrypt, authenticate or verify.

key generation :
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The key is derived from the passphrase depending on the choosen algorithm and arguments. 

In random mode, key and IV will be randomly produced, therefore without using any other data.

In simple mode, key is directly the passphrase, null padded if too short, 
or 'folded and mixed' with itself if too long.
It is not a secure way to produce a key, but some software do proceed that way (MySQL for example).

'Generate' button is enabled when passphrase contains at least one character.

computing authentication code :
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Choose the digest function to use in the list of the 'Authentication (HMAC)' group.
Note : key will be exactly the one displayed, its length will NOT be adjusted to the bloc size,
unlike for encryption.

version 1.7 et above : if no keu is supplied, a simple digest is calculated when possible (SipHash or Poly1305 excepted).

'Clear' button reset all input fields.