Validation of SignedInfo

xml-security is a library that implements XML signatures and encryption. Validation of an XML signature requires verification that the hash value of the related XML-document matches a specific DigestValue-value, but also that the cryptographic signature on the SignedInfo-tree (the one that contains the DigestValue) verifies and matches a trusted public key. If an attacker somehow (i.e. by exploiting a bug in PHP's canonicalization function) manages to manipulate the canonicalized version's DigestValue, it would be possible to forge the signature. This issue has been patched in version 1.6.12 and 5.0.0-alpha.13.