add new output policy in TODO

Author: Lucien Grondin

README.md

@@ -415,6 +415,7 @@ You can specify an optional index :
 * [ ] put everything in a single file
 * [x] use [Jacobian coordinates](https://en.wikibooks.org/wiki/Cryptography/Prime_Curve/Jacobian_Coordinates)
 * [ ] use a better exponentiation method, for instance using precomputations
+* [ ] always output public keys in ASCII, and private keys in binary
 
 
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