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<?php // phpcs:ignore
/**
* Signature handling model helper
*/
class Snapshot_Model_Full_Remote_Signature {
/**
* Gets signature component (key/value pair) delimiter
*
* @return string
*/
public function get_sig_delimiter () {
return ':';
}
/**
* Gets signature component (pairs) delimiter
*
* @return string
*/
public function get_sig_pair_delimiter () {
return '::';
}
/**
* Gets signature algorithm delimiter
*
* @return string
*/
public function get_algo_delimiter () {
return '//';
}
/**
* Gets signature component (key/value pair) as string
*
* @param string $key Key component portion
* @param string $value Value component portion
*
* @return string
*/
public function get_hash_sig_pair ($key, $value) {
return $key . $this->get_sig_delimiter() . $value;
}
/**
* Gets raw (plaintext) signature string from array of components
*
* @param array $components Components to generate the signature from
*
* @return string
*/
public function get_raw_signature ($components= array()) {
$result = array();
foreach ($components as $key => $value) {
$result[] = $this->get_hash_sig_pair($key, $value);
}
return join($this->get_sig_pair_delimiter(), $result);
}
/**
* Gets the hashed version of the plaintext signature
*
* @param string $raw Plaintext signature
* @param string $secret HMAC key
* @param string $algo Preferred hash algorithm to use
*
* @return string
*/
public function get_hashed_signature ($raw, $secret, $algo) {
$algo = $this->is_preferred_algo($algo) ? $algo : $this->get_default_algo();
return $algo . $this->get_algo_delimiter() . hash_hmac($algo, $raw, $secret);
}
/**
* Gets hashed signature from array of signature components
*
* @param array $components Components to generate the signature from
* @param string $secret Secret value to use as HMAC key
* @param string $algo Optional preferred algorithm
*
* @return string
*/
public function get_signature ($components= array(), $secret = '', $algo= false) {
$raw = $this->get_raw_signature($components);
return $this->get_hashed_signature($raw, $secret, $algo);
}
/**
* Check if a signature is in valid format
*
* @param string $signature Signature to check
*
* @return bool
*/
public function is_valid_signature ($signature= false) {
if (empty($signature) || !is_string($signature)) return false;
$valid = false;
$algos = $this->get_preferred_algos();
foreach ($algos as $algo) {
if (!preg_match(
'/^' .
preg_quote($algo, '/') .
preg_quote($this->get_algo_delimiter(), '/') .
'[a-zA-Z0-9]/', $signature
)
) continue;
$valid = true;
break;
}
return $valid;
}
/**
* Gets extracted signature algorithm
*
* Falls back to default implementation algorithm
*
* @param string $signature Signature to extract the algo from
*
* @return string
*/
public function get_signature_algo ($signature= false) {
$fallback = $this->get_default_algo();
$algo = false;
if ($this->is_valid_signature($signature)) {
$tmp = explode($this->get_algo_delimiter(), $signature, 2);
$algo = !empty($tmp[0]) && $this->is_preferred_algo($tmp[0])
? $tmp[0]
: false
;
}
return !empty($algo) ? $algo : $fallback;
}
/**
* Checks if we know the requested hash algorithm
*
* @param string $algo Hash algorithm
*
* @return bool
*/
public function is_known_algo ($algo= false) {
if (empty($algo)) return false;
return in_array( $algo, hash_algos(), true );
}
/**
* Checks whether the hash algorithm is known locally, and allowed for usage
*
* @param string $algo Hash algorithm
*
* @return bool
*/
public function is_preferred_algo ($algo= false) {
if (!$this->is_known_algo($algo)) return false;
return in_array( $algo, $this->get_preferred_algos(), true );
}
/**
* Gets a finite list of preferred hash algorithms
*
* Hash algorithm are listed in order of preference
*
* @return array
*/
public function get_preferred_algos () {
return array(
'sha512',
'sha256',
'sha1',
'md5',
);
}
/**
* Gets the preferred hash algorithm
*
* @param string $preferred Optional preferred hash algorithm
*
* @return string
*/
public function get_preferred_algo ($preferred= false) {
$preferred = !empty($preferred) ? $preferred : $this->get_default_algo();
if (!$this->is_preferred_algo($preferred)) {
$preferred = $this->get_default_algo();
}
return $preferred;
}
/**
* Gets the default hash algorithm for usage
*
* @return string
*/
public function get_default_algo () {
static $preferred;
if (!$preferred) {
foreach ($this->get_preferred_algos() as $algo) {
if (!$this->is_known_algo($algo)) continue;
$preferred = $algo;
break;
}
}
return $preferred;
}
}