• eleijeep@piefed.social
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        8 days ago

        DroidCrypt uses scrypt with N=32768 r=16 p=4 as PBKDF, and AES-256 in GCM mode with tag-length of 128 bits. The ciphertext is output as:

        +------------------------+-----------------------+-------------------------  
        | scrypt salt (16 bytes) | AES-GCM IV (12 bytes) | ciphertext (N bytes) ...  
        +------------------------+-----------------------+-------------------------  
        

        and base64 encoded.

        Your recipient would need to know all of these details to be able to decrypt the text (or use the same app) which is why cryptography is a bit more complicated than just “encrypt it with aes256.”