Fix signature parse verification
This commit is contained in:
Django Doucet
parent
8f80a70ee5
commit
0c7cec3eba
2 changed files with 172 additions and 125 deletions
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@ -1,7 +1,8 @@
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<?php
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namespace Activitypub;
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use phpseclib3\Crypt\RSA;
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// use DateTime;
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// use DateTimeZone;
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/**
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* ActivityPub Signature Class
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@ -10,16 +11,13 @@ use phpseclib3\Crypt\RSA;
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*/
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class Signature {
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const SIGNATURE_PATTERN = '/^
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keyId="(?P<keyId>
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(https?:\/\/[\w\-\.]+[\w]+)
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(:[\d]+)?
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([\w\-\.#\/@]+)
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)",
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(algorithm="(?P<algorithm>[\w\s-]+)",)?
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(headers="(?P<headers>[\(\)\w\s-]+)",)?
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signature="(?P<signature>[\w+\/]+={0,2})"
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/x';
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/**
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* How much leeway to provide on the date header in seconds.
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* Not everybody uses NTP.
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*/
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const MAX_TIME_OFFSET = 10800;
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const DEFAULT_SIGNING_ALGORITHM = 'sha256';
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/**
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* @param int $user_id
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@ -120,136 +118,176 @@ class Signature {
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}
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}
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public static function verify_signature( $request ) {
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public static function verify_signature( $request = null ) {
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$headers = $request->get_headers();
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$headers["(request-target)"][0] = strtolower( $request->get_method() ) . ' /wp-json' . $request->get_route();
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// https://github.com/landrok/activitypub/blob/master/src/ActivityPhp/Server/Http/HttpSignature.php
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$header_data = $request->get_headers();
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$body = $request->get_body();
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if ( !$header_data['signature'][0] ) {
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if ( !$headers ) {
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$headers = self::default_server_headers();
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}
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if ( array_key_exists( 'signature', $headers ) ) {
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$signature_block = self::parse_signature_header( $headers['signature'] );
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} elseif ( array_key_exists( 'authorization', $headers ) ) {
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$signature_block = self::parse_signature_header( $headers['authorization'] );
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}
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if ( !$signature_block ) {
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return false;
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}
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// Split signature into its parts
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$signature_parts = self::splitSignature( $header_data['signature'][0] );
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if ( !count( $signature_parts ) ) {
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$signed_headers = $signature_block['headers'];
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if ( ! $signed_headers ) {
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$signed_headers = ['date'];
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}
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$signed_data = self::get_signed_data( $signed_headers, $signature_block, $headers );
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if ( ! $signed_data ) {
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return false;
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}
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extract( $signature_parts );// $keyId, $algorithm, $headers, $signature
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// Fetch the public key linked from keyId
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$algorithm = self::get_signature_algorithm( $signature_block );
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if ( ! $algorithm ) {
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return false;
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}
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if ( in_array( 'digest', $signed_headers ) && isset( $body ) ) {
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$digest = explode( '=', $headers['digest'], 2 );
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if ( $digest[0] === 'SHA-256' ) {
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$hashalg = 'sha256';
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}
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if ( $digest[0] === 'SHA-512' ) {
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$hashalg = 'sha512';
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}
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// TODO Test
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if ( base64_encode( hash( $hashalg, $body, true ) ) !== $digest[1] ) {
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return false;
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}
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}
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$public_key = $key?? self::get_key( $signature_block['keyId'] );
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return \openssl_verify( $signed_data,$signature_block['signature'], $public_key, $algorithm ) > 0;
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}
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public static function default_server_headers() {
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$headers = array(
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'(request-target)' => strtolower( $_SERVER['REQUEST_METHOD'] ) . ' ' . $_SERVER['REQUEST_URI'],
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'content-type' => $_SERVER['CONTENT_TYPE'],
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'content-length' => $_SERVER['CONTENT_LENGTH'],
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);
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foreach ( $_SERVER as $k => $v ) {
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if ( strpos( $k, 'HTTP_' ) === 0 ) {
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$field = str_replace( '_', '-', strtolower( substr( $k, 5 ) ) );
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$headers[$field] = $v;
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}
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}
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return $headers;
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}
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public static function get_signature_algorithm( $signature_block ) {
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switch ( $signature_block['algorithm'] ) {
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case 'rsa-sha256':
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return 'sha256';
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case 'rsa-sha-512':
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return 'sha512';
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case 'hs2019':
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return self::DEFAULT_SIGNING_ALGORITHM;
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}
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return false;
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}
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public static function parse_signature_header( $header ) {
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$ret = [];
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$matches = [];
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$h_string = implode( ',', (array) $header[0] );
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if ( preg_match( '/keyId="(.*?)"/ism', $h_string, $matches ) ) {
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$ret['keyId'] = $matches[1];
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}
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if ( preg_match( '/created=([0-9]*)/ism', $h_string, $matches ) ) {
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$ret['(created)'] = $matches[1];
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}
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if ( preg_match( '/expires=([0-9]*)/ism', $h_string, $matches ) ) {
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$ret['(expires)'] = $matches[1];
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}
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if ( preg_match( '/algorithm="(.*?)"/ism', $h_string, $matches ) ) {
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$ret['algorithm'] = $matches[1];
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}
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if ( preg_match( '/headers="(.*?)"/ism', $h_string, $matches ) ) {
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$ret['headers'] = explode( ' ', $matches[1] );
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}
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if ( preg_match( '/signature="(.*?)"/ism', $h_string, $matches ) ) {
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$ret['signature'] = base64_decode( preg_replace( '/\s+/', '', $matches[1] ) );
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}
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if ( ( $ret['signature'] ) && ( $ret['algorithm'] ) && ( !$ret['headers'] ) ) {
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$ret['headers'] = ['date'];
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}
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return $ret;
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}
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public static function get_key( $keyId ) {
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// If there was no key passed to verify, it will find the keyId and call this
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// function to fetch the public key from stored data or a network fetch.
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$actor = \strip_fragment_from_url( $keyId );
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$publicKeyPem = \Activitypub\get_publickey_by_actor( $actor, $keyId );
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return rtrim( $publicKeyPem );
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}
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if ( !is_wp_error( $publicKeyPem ) ) {
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// Probably overkill since we already have a seemingly weelformed PEM
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$pkey = \openssl_pkey_get_details( \openssl_pkey_get_public( $publicKeyPem ) );
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// Verify Digest
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$digest_gen = 'SHA-256=' . \base64_encode( \hash( 'sha256', $body, true ) );
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if ( ! isset( $header_data['digest'][0] ) || ( $digest_gen !== $header_data['digest'][0] ) ) {
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public static function get_signed_data( $signed_headers, $signature_block, $headers ) {
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$signed_data = '';
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// This also verifies time-based values by returning false if any of these are out of range.
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foreach ( $signed_headers as $header ) {
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if ( array_key_exists($header, $headers ) ) {
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if ( $header === 'host' ) {
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if ( isset( $headers['x_original_host'] ) ) {
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$signed_data .= 'host: ' . $headers['x_original_host'][0] . "\n";
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} else {
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$signed_data .= $header . ': ' . $headers[$header][0] . "\n";
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}
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} else {
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$signed_data .= $header . ': ' . $headers[$header][0] . "\n";
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}
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}
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if ( $header === '(created)' ) {
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if ( !empty( $signature_block['(created)'] ) && intval( $signature_block['(created)'] ) > time() ) {
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// created in future
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return false;
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}
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// Create a comparison string from the plaintext headers we got
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// in the same order as was given in the signature header,
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$signing_headers = self::getPlainText(
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explode(' ', trim( $headers ) ),
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$request
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);
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// 2 methods because neither works ¯\_(ツ)_/¯
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// phpseclib method
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$rsa = RSA::createKey()
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->loadPublicKey( $pkey['key'])
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->withHash('sha256');
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$verified = $rsa->verify( $signing_headers, \base64_decode( $signature ) );
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if ( $verified > 0 ) {
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\error_log( '$rsa->verify: //return true;' );
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return true;
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} else {
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while ( $ossl_error = openssl_error_string() ) {
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\error_log( '$rsa->verify(): ' . $ossl_error );
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}
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$activity = \json_decode( $body );
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\error_log( 'activity->type: ' . print_r( $activity->type, true ) );
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//return false;
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}
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// openssl method
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$verified = \openssl_verify( $signing_headers,
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\base64_decode( \normalize_whitespace( $signature ) ),
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$pkey['key'],
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\OPENSSL_ALGO_SHA256
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);
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if ( $verified > 0 ) {
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\error_log( 'openssl_verify: //return true;' );
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return true;
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} else {
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while ( $ossl_error = openssl_error_string() ) {
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\error_log( 'openssl_error_string(): ' . $ossl_error );
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}
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//return false;
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}
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$signed_data .= '(created): ' . $signature_block['(created)'] . "\n";
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}
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if ( $header === '(expires)' ) {
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if ( !empty( $signature_block['(expires)'] ) && intval( $signature_block['(expires)'] ) < time() ) {
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// expired in past
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return false;
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}
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/**
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* Split HTTP signature into its parts (keyId, headers and signature)
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*/
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public static function splitSignature( $signature ) {
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$allowedKeys = [
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'keyId',
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'algorithm', // optional
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'headers', // optional
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'signature',
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];
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if (!preg_match(self::SIGNATURE_PATTERN, $signature, $matches)) {
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return [];
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$signed_data .= '(expires): ' . $signature_block['(expires)'] . "\n";
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}
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// Headers are optional
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if (!isset($matches['headers']) || $matches['headers'] == '') {
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$matches['headers'] = 'date';
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if ( $header === 'content-type' ) {
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$signed_data .= $header . ': ' . $headers['content_type'][0] . "\n";
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}
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if ( $header === 'date' ) {
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// allow a bit of leeway for misconfigured clocks.
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$d = new DateTime( $headers[$header][0] );
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$d->setTimeZone( new DateTimeZone('UTC') );
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return array_filter($matches, function($key) use ($allowedKeys) {
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return !is_int($key) && in_array($key, $allowedKeys);
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}, ARRAY_FILTER_USE_KEY );
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}
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$dplus = time() + self::MAX_TIME_OFFSET;
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$dminus = time() - self::MAX_TIME_OFFSET;
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$c = wp_date( 'U' );
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/**
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* Get plain text that has been originally signed
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*
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* @param array $headers HTTP header keys
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* @param \Symfony\Component\HttpFoundation\Request $request
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*/
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public static function getPlainText( $headers, $request ) {
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$url_params = $request->get_url_params();
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if ( isset( $url_params ) && isset( $url_params['user_id'] ) ) {
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$url_params = '';
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}
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$strings = [];
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$request_target = sprintf(
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'%s %s%s',
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strtolower($request->get_method()),
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$request->get_route(),
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$url_params
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);
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foreach ($headers as $value) {
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if ( $value == '(request-target)' ) {
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$strings[] = "$value: " . $request_target;
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} else {
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$strings[] = "$value: " . $request->get_header($value);
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if ( $c > $dplus || $c < $dminus ) {
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// time out of range
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return false;
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}
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}
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return implode("\n", $strings);
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}
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// error_log( '$signed_data: ' . print_r( rtrim( $signed_data, "\n" ), true ) );
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return rtrim($signed_data, "\n");
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}
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public static function generate_digest( $body ) {
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@ -84,7 +84,6 @@ class Inbox {
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// verify signature
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\Activitypub\Signature::verify_signature( $request );
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//\Activitypub\Signature::verify_signature( $headers, $key );
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return $served;
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}
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@ -340,6 +339,16 @@ class Inbox {
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},
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);
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$params['validated'] = array(
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'sanitize_callback' => function( $param, $request, $key ) {
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if ( \is_string( $param ) ) {
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$param = array( $param );
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}
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return $param;
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},
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);
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return $params;
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}
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