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/* Copyright 2019 The ChromiumOS Authors
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
/* Fingerprint sensor crypto operations */
#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|.
*
* @param outkey the pointer to buffer holding the output key.
* @param salt the salt to use in HKDF.
* @return EC_SUCCESS on success and error code otherwise.
*/
int derive_encryption_key(uint8_t *out_key, const uint8_t *salt);
/**
* Derive positive match secret from |input_positive_match_salt| and
* SBP_Src_Key.
*
* @param output buffer to store positive match secret, must be at least
* FP_POSITIVE_MATCH_SECRET_BYTES in size.
* @param input_positive_match_salt the salt for deriving secret, must be at
* least FP_POSITIVE_MATCH_SALT_BYTES in size.
* @return EC_SUCCESS on success and error code otherwise.
*/
int derive_positive_match_secret(uint8_t *output,
const uint8_t *input_positive_match_salt);
/**
* Encrypt |plaintext| using AES-GCM128.
*
* @param key the key to use in AES.
* @param key_size the size of |key| in bytes.
* @param plaintext the plain text to encrypt.
* @param ciphertext buffer to hold encryption result.
* @param text_size size of both |plaintext| and output ciphertext in bytes.
* @param nonce the nonce value to use in GCM128.
* @param nonce_size the size of |nonce| in bytes.
* @param tag the tag to hold the authenticator after encryption.
* @param tag_size the size of |tag|.
* @return EC_SUCCESS on success and error code otherwise.
*/
int aes_gcm_encrypt(const uint8_t *key, int key_size, const uint8_t *plaintext,
uint8_t *ciphertext, int text_size, const uint8_t *nonce,
int nonce_size, uint8_t *tag, int tag_size);
/**
* Decrypt |plaintext| using AES-GCM128.
*
* @param key the key to use in AES.
* @param key_size the size of |key| in bytes.
* @param ciphertext the cipher text to decrypt.
* @param plaintext buffer to hold decryption result.
* @param text_size size of both |ciphertext| and output plaintext in bytes.
* @param nonce the nonce value to use in GCM128.
* @param nonce_size the size of |nonce| in bytes.
* @param tag the tag to compare against when decryption finishes.
* @param tag_size the length of tag to compare against.
* @return EC_SUCCESS on success and error code otherwise.
*/
int aes_gcm_decrypt(const uint8_t *key, int key_size, uint8_t *plaintext,
const uint8_t *ciphertext, int text_size,
const uint8_t *nonce, int nonce_size, const uint8_t *tag,
int tag_size);
#endif /* __CROS_EC_FPSENSOR_CRYPTO_H */
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