From 6133770db4d827ee5834a96b81627875811c6eab Mon Sep 17 00:00:00 2001
From: Tobias Brunner <tobias@strongswan.org>
Date: Thu, 18 Dec 2014 09:13:38 +0100
Subject: [PATCH] x509: Use subjectKeyIdentifier provided by issuer cert when
 checking CRL issuer

Some CAs don't use SHA-1 hashes of the public key as subjectKeyIdentifier and
authorityKeyIdentifier.  If that's the case we can't force the
calculation of the hash to compare that to authorityKeyIdentifier in the CRL,
instead we use the subjectKeyIdentifier stored in the issuer certificate, if
available.  Otherwise, we fall back to the SHA-1 hash (or comparing the
DNs) as before.
---
 src/libstrongswan/plugins/x509/x509_crl.c | 39 +++++++++++------------
 1 file changed, 18 insertions(+), 21 deletions(-)

diff --git a/src/libstrongswan/plugins/x509/x509_crl.c b/src/libstrongswan/plugins/x509/x509_crl.c
index 1f3f60daa..4d7e7bd10 100644
--- a/src/libstrongswan/plugins/x509/x509_crl.c
+++ b/src/libstrongswan/plugins/x509/x509_crl.c
@@ -451,6 +451,7 @@ METHOD(certificate_t, issued_by, bool,
 	signature_scheme_t scheme;
 	bool valid;
 	x509_t *x509 = (x509_t*)issuer;
+	chunk_t keyid = chunk_empty;
 
 	/* check if issuer is an X.509 CA certificate */
 	if (issuer->get_type(issuer) != CERT_X509)
@@ -462,6 +463,23 @@ METHOD(certificate_t, issued_by, bool,
 		return FALSE;
 	}
 
+	/* compare keyIdentifiers if available, otherwise use DNs */
+	if (this->authKeyIdentifier.ptr)
+	{
+		keyid = x509->get_subjectKeyIdentifier(x509);
+		if (keyid.len && !chunk_equals(keyid, this->authKeyIdentifier))
+		{
+			return FALSE;
+		}
+	}
+	if (!keyid.len)
+	{
+		if (!this->issuer->equals(this->issuer, issuer->get_subject(issuer)))
+		{
+			return FALSE;
+		}
+	}
+
 	scheme = signature_scheme_from_oid(this->algorithm);
 	if (scheme == SIGN_UNKNOWN)
 	{
@@ -472,27 +490,6 @@ METHOD(certificate_t, issued_by, bool,
 	{
 		return FALSE;
 	}
-
-	/* compare keyIdentifiers if available, otherwise use DNs */
-	if (this->authKeyIdentifier.ptr)
-	{
-		chunk_t fingerprint;
-
-		if (!key->get_fingerprint(key, KEYID_PUBKEY_SHA1, &fingerprint) ||
-			!chunk_equals(fingerprint, this->authKeyIdentifier))
-		{
-			key->destroy(key);
-			return FALSE;
-		}
-	}
-	else
-	{
-		if (!this->issuer->equals(this->issuer, issuer->get_subject(issuer)))
-		{
-			key->destroy(key);
-			return FALSE;
-		}
-	}
 	valid = key->verify(key, scheme, this->tbsCertList, this->signature);
 	key->destroy(key);
 	if (valid && schemep)