known_hosts.c File Reference

📜 SSH known_hosts file parser for host key verification and trust management More...

Go to the source code of this file.

Functions
asciichat_error_t	check_known_host (const char *server_ip, uint16_t port, const uint8_t server_key[32])
	Check if server key is in known_hosts.
asciichat_error_t	check_known_host_no_identity (const char *server_ip, uint16_t port)
	Check known_hosts for servers without identity key (no-identity entries)
asciichat_error_t	add_known_host (const char *server_ip, uint16_t port, const uint8_t server_key[32])
	Add server to known_hosts.
asciichat_error_t	remove_known_host (const char *server_ip, uint16_t port)
	Remove server from known_hosts.
void	compute_key_fingerprint (const uint8_t key[ED25519_PUBLIC_KEY_SIZE], char fingerprint[CRYPTO_HEX_KEY_SIZE_NULL])
bool	prompt_unknown_host (const char *server_ip, uint16_t port, const uint8_t server_key[32])
	Interactive prompt for unknown host - returns true if user wants to add, false to abort.
bool	display_mitm_warning (const char *server_ip, uint16_t port, const uint8_t expected_key[32], const uint8_t received_key[32])
	Display MITM warning with key comparison and prompt user for confirmation.
bool	prompt_unknown_host_no_identity (const char *server_ip, uint16_t port)
	Interactive prompt for unknown host without identity key - returns true if user wants to continue, false to abort.
void	known_hosts_cleanup (void)
	Cleanup function to free cached known_hosts path.
Known Hosts Management
const char *	get_known_hosts_path (void)
	Get the path to the known_hosts file.

Detailed Description

📜 SSH known_hosts file parser for host key verification and trust management

Definition in file known_hosts.c.

Function Documentation

compute_key_fingerprint()

void compute_key_fingerprint	(	const uint8_t	key[ED25519_PUBLIC_KEY_SIZE],
		char	fingerprint[CRYPTO_HEX_KEY_SIZE_NULL]
	)

Definition at line 536 of file known_hosts.c.

                                                                                                                     {
  uint8_t hash[HMAC_SHA256_SIZE];
  crypto_hash_sha256(hash, key, ED25519_PUBLIC_KEY_SIZE);
 
  // Build hex string byte by byte to avoid buffer overflow issues
  for (int i = 0; i < HMAC_SHA256_SIZE; i++) {
    uint8_t byte = hash[i];
    fingerprint[i * 2] = "0123456789abcdef"[byte >> 4];      // High nibble
    fingerprint[i * 2 + 1] = "0123456789abcdef"[byte & 0xf]; // Low nibble
  }
  fingerprint[CRYPTO_HEX_KEY_SIZE] = '\0';
}

References CRYPTO_HEX_KEY_SIZE, ED25519_PUBLIC_KEY_SIZE, and HMAC_SHA256_SIZE.

Referenced by display_mitm_warning(), and prompt_unknown_host().