Certificates

From 3dbrew
Jump to: navigation, search

Overview[edit]

Certificates contain cryptography information for verifying Signatures. These certificates are also signed. The parent/child relationship between certificates, makes all the certificates effectively signed by 'Root', the public key for which is stored in NATIVE_FIRM.

Format[edit]

Offset Size Description
0x0 0x4 Signature Type
0x4 X Signature with Padding (aligning next data to 0x40 bytes)
0x4 + X 0x40 Issuer
0x44 + X 0x4 Key Type
0x48 + X 0x40 Name
0x88 + X 0x4 Unknown
0x8C + X * Public Key

Signature[edit]

The signature method used to sign the certificate can be determined by checking the Signature Type:

Value Signature Method Signature Size Padding Size
0x010000 RSA_4096 SHA1 (Unused for 3DS) 0x200 0x3C
0x010001 RSA_2048 SHA1 (Unused for 3DS) 0x100 0x3C
0x010002 Elliptic Curve with SHA1 (Unused for 3DS) 0x3C 0x40
0x010003 RSA_4096 SHA256 0x200 0x3C
0x010004 RSA_2048 SHA256 0x100 0x3C
0x010005 ECDSA with SHA256 0x3C 0x40

The hash for the signature is calculated over the actual certificate data(from the start of the "Issuer", to the end of the "Public Key", aligned to 0x40 bytes).

Public Key[edit]

Determining the type of public key stored, is done by checking the key type:

Value Key Type
0x0 RSA_4096
0x1 RSA_2048
0x2 Elliptic Curve

RSA[edit]

This contains the Public Key(i.e. Modulus & Public Exponent)

4096 Bit[edit]

Offset Size Description
0x0 0x200 Modulus
0x200 0x4 Public Exponent
0x204 0x34 Padding

2048 Bit[edit]

Offset Size Description
0x0 0x100 Modulus
0x100 0x4 Public Exponent
0x104 0x34 Padding

ECC[edit]

This contains the ECC public key, and is as follows:

Offset Size Description
0x0 0x3C Public Key
0x3C 0x3C Padding