Nokia C3

Nokia C3 official promotional image.

Nokia C3 is an entry-level device released in August 2020.

### vbmeta signature parsing

Following content is parsed from HMDSW\_GMR-1040-0-00CN-B01\_600CN\_10\_20200605\_sprocomm\_E6005N.devkit.pac.lzma2.[SHA256SUM].7z firmware.
Hope it can be helpful for bootloader unlock key calculation.

```
Minimum libavb version:   1.0
Header Block:             256 bytes
Authentication Block:     576 bytes
Auxiliary Block:          13568 bytes
Algorithm:                SHA256_RSA4096
Rollback Index:           0
Flags:                    0
Release String:           'avbtool 1.1.0'
      Partition Name:          boot
      Rollback Index Location: 1
      Public key (sha1):       52be5dab4dea1313b824173667719d056808179d
    Chain Partition descriptor:
      Partition Name:          dtbo
      Rollback Index Location: 10
      Public key (sha1):       52be5dab4dea1313b824173667719d056808179d
    Chain Partition descriptor:
      Partition Name:          recovery
      Rollback Index Location: 2
      Public key (sha1):       abdb7f1028b247d8074cbaf64f436e75bf725a9e
    Chain Partition descriptor:
      Partition Name:          socko
      Rollback Index Location: 11
      Public key (sha1):       cb2a7e23d7bfa29c4b7aeb5cf0a92b6dcc63c029
    Chain Partition descriptor:
      Partition Name:          odmko
      Rollback Index Location: 12
      Public key (sha1):       605bfce862206a8cbf4ab65e1fdc6bb1327ab388
    Chain Partition descriptor:
      Partition Name:          vbmeta_system
      Rollback Index Location: 3
      Public key (sha1):       3c03bda3a52708d51c3ea1f69f7e739e4f00eb75
    Chain Partition descriptor:
      Partition Name:          vbmeta_vendor
      Rollback Index Location: 4
      Public key (sha1):       720f86571aa64a77c1a49f034e6f8b8289d61e2d
    Chain Partition descriptor:
      Partition Name:          l_modem
      Rollback Index Location: 6
      Public key (sha1):       cbb8bd85d34be4fa1212f44be8febf2118fc406d
    Chain Partition descriptor:
      Partition Name:          l_ldsp
      Rollback Index Location: 7
      Public key (sha1):       cbb8bd85d34be4fa1212f44be8febf2118fc406d
    Chain Partition descriptor:
      Partition Name:          l_gdsp
      Rollback Index Location: 8
      Public key (sha1):       cbb8bd85d34be4fa1212f44be8febf2118fc406d
    Chain Partition descriptor:
      Partition Name:          pm_sys
      Rollback Index Location: 9
      Public key (sha1):       cbb8bd85d34be4fa1212f44be8febf2118fc406d

```

### Permission Granting

All of Nokia C3 seems using the same auth response message with security version 105:

```
BXJvMWRfMocDA6IbjeRgZ59ZQL5vuYgESoBvFApYSSpI0ISNBRV9ght6OwuHxl+u+2G66ZSa0ao5SWfCsRu3u/s6hiAb+M78Ht9DGPspwrYOvp8rdJIxZicGIJlRbK4QA4eDDQiBjFEOCxG5bmNejt2scDE/9g9VaXXdQL307EDXoIlCpBaaTWTBh1W7nw+VsJ25gh3NqcHevLQq3Snmh2wL5bRECaGGZmqZL0WDHMMR9cnOo/0bb2PpAiKBiJevP6cw1zGzr4vphvvNtwb0qnhMA0nxYZcqZkAVqHUGvgB5EL3WEM2ppKQ+pfGCu8CW4SSFrELPCeCFMjqXrEYLdw==

```

### Bootloader Unlock Theory

You may use the special fastboot binary compiled by Unisoc, which contains this command:

```
fastboot flashing unlock_bootloader /path/to/unlock/key/file
```

Unisoc has a Linux binary available, in fact fastboot-android.exe contained in OST LA also has this command available.