# Certificates

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## 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 | Expiration time as UNIX Timestamp, used at least for CTCert |

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 |