Difference between revisions of "Amiibo"

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Revision as of 04:54, 17 April 2015

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. The read page data for page[0x3] must match little-endian 0xEEFF10F1.
  • 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. Minus the configuration pages at the end, the total is 0x82/130 pages. The following is the structure of the NFC pages:

NFC page Total pages Raw byte offset in EEPROM Total byte size Description
0x0 0x4 0x10 0x10 Same as standard NTAG215: 9-byte serial-number, "internal" u8 value, two lock bytes then the "Capability Container (CC)" page.
0x4 0x1 0x10 0x4 Last 3-bytes here are used with the following HMAC where the size is 0x1DF-bytes. The u16 starting at byte1 is used for the first two bytes in the 0x40-byte input buffer for Amiibo crypto init. The first byte is normally 0xA5. The remaining bytes are initially(before the Amiibo is written to) all-zero. Byte[2](maybe big-endian u16 starting at byte1?) here is incremented each time the Amiibo is written to.
0x5 0x8 0x14 0x20 The system crypts 0x1A0-bytes with some data from here, see below.
0xD 0x8 0x34 0x20 SHA256-HMAC hash. The first 0x18-bytes of this hash is section3 in the encrypted buffer.
0x15 0xB 0x54 0x2C This is plaintext data, see below.
0x20 0x8 0x80 0x20 SHA256-HMAC hash 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.
0x28 0x45 0xA0 0x114 This is section1 in the encrypted buffer.
0x6D 0x15 0x1B4 0x54 This is section2 in the encrypted buffer.

Structure of the data starting at page 0x15

Offset Size Description
0x0 0xC ?
0xC 0x20 Probably a SHA256-HMAC hash.

Encrypted data buffer structure

Encrypted buffer offset Raw byte offset in NFC EEPROM NFC page Byte size Notes
0x0 0x14 0x5 0x20
0x20 0xA0 0x28 0x114
0x134 0x1B4 0x6D 0x54
0x188 0x34 0xD 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 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 Flags. The low 4-bits here are copied to the struct used with NFC:GetAmiiboSettings. The below setup date is only loaded when bit4 and/or bit5 here are set, otherwise value 0 is used instead for the date. Bit4=1 indicates that the Amiibo was setup with amiibo Settings: NFC:GetAmiiboSettings will return an all-zero struct when this is not set.

Bit5=1 indicates that the AppData was initialized. NFC:InitializeWriteAppData will return an error if this is value 1, when successful that command will then set this bit to value 1.

0x1 0x1 Unknown. The low 4-bits here are copied to the struct used with NFC:GetAmiiboSettings.
0x2 0x2 This big-endian u16 counter is incremented each time that the CRC32 at offset 0x8 gets updated by NFC:InitializeWriteAppData, due to that value not matching the calculated one. When this value is already 0xFFFF, this counter won't be updated anymore.
0x4 0x2 u16 big-endian date value, see below. This is the date for when the Amiibo was initially setup in amiibo Settings. This is also written by NFC:InitializeWriteAppData.
0x6 0x2 u16 big-endian date value, see below. This is the date for when the Amiibo was last written to.
0x8 0x4 Big-endian CRC32 value with initialval=~0, with the 8-byte output from Cfg:GenHashConsoleUnique. This is written by NFC:InitializeWriteAppData, when the current value doesn't match the calculated one.
0xC 0x14(10*2) UTF-16BE Amiibo nickname.
0x20 0x60 Owner Mii.
0x80 0x8 Big-endian application programID/titleID from the application which initialized the AppData, zero otherwise. This is only written, not compared with the user application titleID: doing the latter would break games' cross-platform compatibility with 3DS<>Wii U(Super Smash Bros 3DS/Wii U for example).
0x88 0x2 u16 big-endian. This value is incremented each time the Amiibo is written to. When this value is already 0xFFFF, this counter won't be updated anymore.
0x8A 0x4 Big-endian u32 Amiibo AppID.
0x8E 0x2 ?
0x90 0x20 Probably a SHA256-HMAC hash.

Format of the big-endian date values:

Bit Description
0-4 Day
5-8 Month
9-15 Year, relative to 2000.