diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/fpsensor_crypto.h | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/include/fpsensor_crypto.h b/include/fpsensor_crypto.h index ebda41bcb9..e01a38799d 100644 --- a/include/fpsensor_crypto.h +++ b/include/fpsensor_crypto.h @@ -8,6 +8,29 @@ #ifndef __CROS_EC_FPSENSOR_CRYPTO_H #define __CROS_EC_FPSENSOR_CRYPTO_H +#include <stddef.h> + +#include "sha256.h" + +#define HKDF_MAX_INFO_SIZE 128 +#define HKDF_SHA256_MAX_BLOCK_COUNT 255 + +/** + * Expand hkdf pseudorandom key |prk| to length |out_key_size|. + * + * @param out_key the buffer to hold output key material. + * @param out_key_size length of output key in bytes. Must be less than + * or equal to HKDF_SHA256_MAX_BLOCK_COUNT * SHA256_DIGEST_SIZE bytes. + * @param prk pseudorandom key. + * @param prk_size length of |prk| in bytes. + * @param info optional context. + * @param info_size size of |info| in bytes, must be less than or equal to + * HKDF_MAX_INFO_SIZE bytes. + * @return EC_SUCCESS on success and error code otherwise. + */ +int hkdf_expand(uint8_t *out_key, size_t out_key_size, const uint8_t *prk, + size_t prk_size, const uint8_t *info, size_t info_size); + /** * Derive hardware encryption key from rollback secret and |salt|. * |