Here is a progress on nintendo 3DS...guy named Crediar released a 3DSaveTool 0.1 for 3DS players.Players can use it to detect the xor key and encrypt/decrypt EEPROM savefiles from 3ds games.
It's been confirmed by now that 3DS games save inside the cartridge just like DS/DSi games, and that the saves are encrypted. Fortunately the encryption scheme seems simple, as crediar has not only found out how it works, but created a tool that will attempt to both find the key used (which differs per game), and use it to decrypt or re-encrypt a save file.
This means that users with tools such as the NDS Backup Adapter+ can now fiddle with the save games of their 3DS systems, though restoring a modified save seems iffy at the moment.
And also some related tweets
->@0xabad1dea The EEPROM of 3DS cards is encrypted via an unique per game 512byte xor'key, game roms seem(!) to use that aswell not sure yet!! vor ungefähr 3 Stunden via web als Antwort auf 0xabad1dea
->just released 3DSaveTool you can use it to find the xor key and encrypt/decrypt EEPROM savefiles from 3ds games! 3DSaveTool - 3dbrew vor ungefähr 4 Stunden via web
->Ooops looks like the same fail applies to games! Private Paste - Pastie (No April's Fool!) 2:35 AM Apr 1st via web
->That savefile is from the EEPROM which can freely be written and read! Yes 3DS card games still save to the card! 1:50 AM Apr 1st via web
->Good news everyone! Erant found a slight flaw in the savefile encryption of Ridge Racer! Line 405 is my nick Private Paste - Pastie 6:58 AM Mar 31st via web
Download : 3DSaveTool 0.1