Amiibo

From 3dbrew
Jump to navigation Jump to search

Amiibo are NFC figures made by Nintendo, used in games in different forms (different in each game). It can be used with the New3DS and the Old3DS with an IR peripheral.

Technical specifications

See also here.

Specifications can be found on this image, which is a compilation of screenshots made by scanning a Samus amiibo with the Android App "NFC TagInfo": Amiibonfctaginfo.png

See here regarding the Amiibo encryption.

The NFC tag for Amiibo is NTAG215.

AUTH_PWD

The NFC 32bit password for the PWD_AUTH command(for enabling write-access to the encrypted NFC pages / etc), appears to be generated from unknown data that doesn't change when the Amiibo data pages are being updated.

NTAG215 commands

Amiibo reading

  • GET_VERSION
  • READ, startpage=0x03
  • PWD_AUTH
  • FAST_READ: startpage=0x00, endpage=0x3B
  • FAST_READ: startpage=0x3C, endpage=0x77
  • FAST_READ: startpage=0x78, endpage=0x86

Therefore, *all* pages from the Amiibo NFC tag are read, including the configuration pages at the end.

Amiibo writing

  • Use the same commands under the above reading section, then use those first 3 commands again.
  • Multiple WRITE commands for writing to pages 0x04..0x0C. The first byte for page[4] is zero here.
  • Multiple WRITE commands for writing to pages 0x20..0x81.
  • Use the last 3 commands from the above reading section.
  • WRITE: page=0x04, same data as before except first byte is 0xA5 this time.
  • FAST_READ: startpage=0x04, endpage=0x04

NFC pages

Each page is 4-bytes, there is a total of 0x87/135 pages. The following is the structure of the NFC pages:

NFC page Total pages Raw byte offset in EEPROM Total byte size Description
0 4 0x10 0x10 Same as standard NTAG215: 9-byte serial-number, "internal" u8 value, two lock bytes then the "Capability Container (CC)" page.
4 1 0x10 0x4 Last 3-bytes here are used with the following HMAC. The first byte is normally 0xA5. The remaining bytes are initially(before the Amiibo is written to) all-zero. Byte[2] here is increased each time the Amiibo is written to.
5 0x14 The system crypts 0x1A0-bytes with a buffer containing data loaded from here.
0x20/32 8 0x80 0x20 SHA256-HMAC over 0x1DF-bytes: first 3-bytes are from the last 3-bytes of page[4], the rest is over the first 0x1DC-bytes of the plaintext data.

Encrypted data buffer structure

Encrypted buffer offset Byte offset in the actual NFC data, relative to page[5] Size Notes
0x0 0x0 0x20
0x20 0x8C 0x114
0x134 0x1A0 0x54
0x188 0x20 0x18 This data is included in the crypto buffer, even though this data isn't actually encrypted(this is part of a hash).

Structure of the plaintext data

Offset Size Description
0x0 0xB0 Amiibo settings are stored within here.
0xB0 0xD8 AppData, for the user-application with the programID specified in the above Amiibo settings. The data stored here is application-specific.
0x188 0x18 Not used in "decrypted" form, since this isn't encrypted to begin with.

Structure of Amiibo settings

Offset Size Description
0x0 0x1 Unknown. The low 4-bits here are copied to the struct used with NFC:GetAmiiboSettings.
0x1 0x1 Unknown. The low 4-bits here are copied to the struct used with NFC:GetAmiiboSettings.
0x2 0x2 ?
0x4 0x2 u16 big-endian, unknown.
0x6 0x6 ?
0xC 0x14(10*2) UTF-16BE Amiibo nickname.
0x20 0x60 Owner Mii.
0x80 0x8 Application programID for the AppData, zero otherwise.
0x88 0x4 ?
0x8C 0x4 ?
0x90 0x20 Probably a SHA256-HMAC hash.