readme
# ESP Encrypted Image Abstraction Layer
[](https://components.espressif.com/components/espressif/esp_encrypted_img)
This component provides an API interface to decrypt data defined in "ESP Encrypted Image" format. This format is as specified at [Image Format](#image-format)
This component can help in integrating pre encrypted firmware in over-the-air updates. Additionally, this component can also be used for other use-cases which requires addition of encryption layer for custom data.
## Image Format

```c
typedef struct {
char magic[4];
char enc_gcm[384];
char iv[16];
char bin_size[4];
char auth[16];
char extra_header[88];
} pre_enc_bin_header;
```
The above struct represents encrypted image header.
Note:
* RSA-3072 key is provided to the tool externally. You can generate RSA key pair using following command:
`openssl genrsa -out rsa_key/private.pem 3072`
* AES-GCM key and IV are generated by the tool itself.
## Tool Info
This component also contains tool ([esp_enc_img_gen.py](https://github.com/espressif/idf-extra-components/blob/master/esp_encrypted_img/tools/esp_enc_img_gen.py)) to generate encrypted images using RSA3072 public key.
### Encrypt the image
```
python esp_enc_img_gen.py encrypt /path/to/input.bin /path/to/RSA-public-key /path/to/enc.bin
```
### Decrypt the image
```
python esp_enc_img_gen.py decrypt /path/to/enc.bin /path/to/RSA-private-key /path/to/output.bin
```
To know more about the tool, use command:
`python esp_enc_img-gen.py --help`
## API Reference
To learn more about how to use this component, please check API Documentation from header file [esp_encrypted_img.h](https://github.com/espressif/idf-extra-components/blob/master/esp_encrypted_img/include/esp_encrypted_img.h)
changelog
## 2.2.0
### Enhancements:
- Added an API to get the size of pre encrypted binary image header, this could be useful while computing entire decrypted image length: `esp_encrypted_img_get_header_size`
## 2.1.0
### Enhancements:
- Added an API to abort the decryption process: `esp_encrypted_img_decrypt_abort`
- Added an API to check if the complete data has been received: `esp_encrypted_img_is_complete_data_received`
## 2.0.4
- `rsa_pub_key` member of `esp_decrypt_cfg_t` structure is now deprecated. Please use `rsa_priv_key` instead.
- `rsa_pub_key_len` member of `esp_decrypt_cfg_t` structure is now deprecated. Please use `rsa_priv_key_len` instead.