(krb5_verify_checksum): New function

git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@1299 ec53bebd-3082-4978-b11e-865c3cabbd6b

lib/krb5/checksum.c

@@ -25,3 +25,26 @@ krb5_create_checksum (krb5_context context,
   md4_finito (&m, result->checksum.data);
   return 0;
 }
+
+krb5_error_code
+krb5_verify_checksum (krb5_context context,
+		      void *ptr,
+		      size_t len,
+		      Checksum *cksum)
+{
+  struct md4 m;
+  u_char csum[16];
+
+  if (cksum->cksumtype != CKSUMTYPE_RSA_MD4)
+    return KRB_AP_ERR_INAPP_CKSUM;
+  if (cksum->checksum.length != 16)
+    return KRB_AP_ERR_MODIFIED;
+
+  md4_init (&m);
+  md4_update (&m, ptr, len);
+  md4_finito (&m, csum);
+  if (memcmp (cksum->checksum.data, csum, 16) == 0)
+    return 0;
+  else
+    return KRB_AP_ERR_MODIFIED;
+}