esp_efuse_write_key() function

Program a block of key data to an efuse block The burn of a key, protection bits, and a purpose happens in batch mode.

Syntax

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Summary

Declaration

Definition

from esp_efuse.h:729

esp_err_t esp_efuse_write_key(esp_efuse_block_t block, esp_efuse_purpose_t purpose, const void *key, size_t key_size_bytes);

Implemented in esp_efuse_api_key.c:187

Arguments

Argument

Description

block

Block to read purpose for. Must be in range EFUSE_BLK_KEY0 to EFUSE_BLK_KEY_MAX. Key block must be unused (esp_efuse_key_block_unused).

purpose

Purpose to set for this key. Purpose must be already unset.

key

Pointer to data to write.

key_size_bytes

Bytes length of data to write.

Return value

- ESP_OK: Successful. - ESP_ERR_INVALID_ARG: Error in the passed arguments. - ESP_ERR_INVALID_STATE: Error in efuses state, unused block not found. - ESP_ERR_EFUSE_REPEATED_PROG: Error repeated programming of programmed bits is strictly forbidden. - ESP_ERR_CODING: Error range of data does not match the coding scheme.

Notes

This API also enables the read protection efuse bit for certain key blocks like XTS-AES, HMAC, ECDSA etc. This ensures that the key is only accessible to hardware peripheral. For SoC's with capability `SOC_EFUSE_ECDSA_USE_HARDWARE_K` (e.g., ESP32-H2), this API writes an additional efuse bit for ECDSA key purpose to enforce hardware TRNG generated k mode in the peripheral.