ciphers.h

Headers for the packet encryption class.

They are used to encrypt single packets.

CIPHERS_MAX_KEY_SIZE

the length of keys in bytes 

1
20
CIPHER_MAX_BLOCK_SIZE
1
16
CIPHER_MAX_CONTEXT_SIZE

Context sizes needed for the different ciphers. 

1
1

Always order by number of bytes descending!!!

threedes needs 24 bytes aes needs CIPHERS_MAX_KEY_SIZE bytes

CIPHER_ERR_INVALID_KEY_SIZE
1
-3
CIPHER_ERR_INVALID_LENGTH
1
-4
CIPHER_ERR_ENC_FAILED
1
-5
CIPHER_ERR_DEC_FAILED
1
-6
CIPHER_ERR_BAD_CONTEXT_SIZE

Is returned by the cipher_init functions, if the coresponding alogirithm has not been included in the build. 

1
0
CIPHER_INIT_SUCCESS

Returned by cipher_init upon succesful initialization of a cipher. 

1
1
struct cipher_interface_st cipher_interface_t

BlockCipher-Interface for the Cipher-Algorithms.

const ciphers.h::cipher_interface_t * cipher_id_t
const cipher_id_t CIPHER_AES_128
int cipher_init(cipher_t * cipher, cipher_id_t cipher_id, const uint8_t * key, uint8_t key_size)

Initialize new cipher state.

Parameters

cipher:cipher struct to init (already allocated memory)
cipher_id:cipher algorithm id
key:encryption key to use
key_size:length of the encryption key

Return values

  • CIPHER_INIT_SUCCESS if the initialization was successful.
  • CIPHER_ERR_BAD_CONTEXT_SIZE if CIPHER_MAX_CONTEXT_SIZE has not been defined (which means that the cipher has not been included in the build)
  • The command may return CIPHER_ERR_INVALID_KEY_SIZE if the key size is not valid.
int cipher_encrypt(const cipher_t * cipher, const uint8_t * input, uint8_t * output)

Encrypt data of BLOCK_SIZE length *.

Parameters

cipher:Already initialized cipher struct
input:pointer to input data to encrypt
output:pointer to allocated memory for encrypted data. It has to be of size BLOCK_SIZE

Return values

  • The result of the encrypt operation of the underlying cipher, which is always 1 in case of success
  • A negative value for an error
int cipher_decrypt(const cipher_t * cipher, const uint8_t * input, uint8_t * output)

Decrypt data of BLOCK_SIZE length *.

Parameters

cipher:Already initialized cipher struct
input:pointer to input data (of size BLOCKS_SIZE) to decrypt
output:pointer to allocated memory for decrypted data. It has to be of size BLOCK_SIZE

Return values

  • The result of the decrypt operation of the underlying cipher, which is always 1 in case of success
  • A negative value for an error
int cipher_get_block_size(const cipher_t * cipher)

Get block size of cipher *.

Parameters

cipher:Already initialized cipher struct

Return values

  • The cipher’s block size (in bytes)
struct cipher_context_t

the context for cipher-operations

uint8_t context()

buffer for cipher operations

struct cipher_interface_st

BlockCipher-Interface for the Cipher-Algorithms.

uint8_t block_size

Blocksize of this cipher.

uint8_t max_key_size

Maximum key size for this cipher.

int(* init()

the init function

int(* encrypt()

the encrypt function

int(* decrypt()

the decrypt function

struct cipher_t

basic struct for using block ciphers contains the cipher interface and the context

const ciphers.h::cipher_interface_t * interface

BlockCipher-Interface for the Cipher-Algorithms.

cipher_context_t context

The encryption context (buffer) for the algorithm.