API Overview

int scramble_init_from_file(const char *keyfile, scramble_crypt_t c4, scramble_crypt_t c6, int *do_mac)

Initializes library from a keyfile and sets up underlying cryptographical mechanism for scrambling of IPv4 (c4) and IPv6 (c6) addresses. See scramble_crypt_t for possible values of c4 and c6. Typically used are: SCRAMBLE_NONE for no scrambling or SCRAMBLE_AES for scrambling using fast AES cypher. If the keyfile does not exist, it is created. This function internally calls scramble_readstate() and scrable_init(). Returns 0 if successful. SCRAMBLE_BLOWFISH uses blowfish cypher. While previously widely used, it's no longer recommended, as scrambling of ipv6 addresses can be very slow.

int32_t   scramble_ip4(uint32_t input, int pass_bits)
int32_t unscramble_ip4(uint32_t input, int pass_bits)

Scrambles or un-scrambles (input) IP address passing through first (pass_bits); the scrambled ip address is returned. Please note that even if (pass_bits) is 0, first few bits will be passed through to preserve class of the input IP. Both input and output IPs are in network byte order. Note that unscrambling is a costly operation and unscrambling a large number of different addresses can take a long time.

void   scramble_ip6(struct in6_addr *input, int pass_bits)
void unscramble_ip6(struct in6_addr *input, int pass_bits)

Scrambles or un-scrambles IPv6 address pointed to by (input) in-place , passing through first (pass_bits). Addresses are in network byte order. Note that unscrambling is a costly operation and unscrambling a large number of different addresses can take a long time.

int scramble_readstate(const char *keyfile, scramble_state_t *s)
int scramble_savestate(const char *keyfile, const scramble_state_t *s)

These functions can read scrambling keys from keyfile into memory pointed to by (s), or save/write previously initialized state (s) to a (keyfile). After state is read, the library still needs to be initialized by calling scramble_init() Return 0 on success.

int scramble_init(const scramble_state_t *s)

Initializes library using state pointed by (s). Returns 0 on success.