krz/vox-populi

 1<?php
 2
 3namespace Eher\OAuth\SignatureMethod;
 4
 5/**
 6 * The RSA-SHA1 signature method uses the RSASSA-PKCS1-v1_5 signature algorithm as defined in
 7 * [RFC3447] section 8.2 (more simply known as PKCS#1), using SHA-1 as the hash function for
 8 * EMSA-PKCS1-v1_5. It is assumed that the Consumer has provided its RSA public key in a
 9 * verified way to the Service Provider, in a manner which is beyond the scope of this
10 * specification.
11 *   - Chapter 9.3 ("RSA-SHA1")
12 */
13abstract class RsaSha1 extends SignatureMethod {
14  public function get_name() {
15    return "RSA-SHA1";
16  }
17
18  // Up to the SP to implement this lookup of keys. Possible ideas are:
19  // (1) do a lookup in a table of trusted certs keyed off of consumer
20  // (2) fetch via http using a url provided by the requester
21  // (3) some sort of specific discovery code based on request
22  //
23  // Either way should return a string representation of the certificate
24  protected abstract function fetch_public_cert(&$request);
25
26  // Up to the SP to implement this lookup of keys. Possible ideas are:
27  // (1) do a lookup in a table of trusted certs keyed off of consumer
28  //
29  // Either way should return a string representation of the certificate
30  protected abstract function fetch_private_cert(&$request);
31
32  public function build_signature($request, $consumer, $token) {
33    $base_string = $request->get_signature_base_string();
34    $request->base_string = $base_string;
35
36    // Fetch the private key cert based on the request
37    $cert = $this->fetch_private_cert($request);
38
39    // Pull the private key ID from the certificate
40    $privatekeyid = openssl_get_privatekey($cert);
41
42    // Sign using the key
43    $ok = openssl_sign($base_string, $signature, $privatekeyid);
44
45    // Release the key resource
46    openssl_free_key($privatekeyid);
47
48    return base64_encode($signature);
49  }
50
51  public function check_signature($request, $consumer, $token, $signature) {
52    $decoded_sig = base64_decode($signature);
53
54    $base_string = $request->get_signature_base_string();
55
56    // Fetch the public key cert based on the request
57    $cert = $this->fetch_public_cert($request);
58
59    // Pull the public key ID from the certificate
60    $publickeyid = openssl_get_publickey($cert);
61
62    // Check the computed signature against the one passed in the query
63    $ok = openssl_verify($base_string, $decoded_sig, $publickeyid);
64
65    // Release the key resource
66    openssl_free_key($publickeyid);
67
68    return $ok == 1;
69  }
70}