They will not actually break encryption. The encryption is sort of the envelope in classic postal mail and will not be touched.
Your chat tool is like a paper and pencil. Right now you use normal paper. They will take care you can only use thosehwrite through paper (known from paper forms).
Once you hit 'send': the write through form gets split - the pages are
1. For your envelope, which is transported safely
2. For them - to see if you do evil