qpdf-9.1.0

[Bruce Dubbs]

New minor version.

[Bruce Dubbs]

9.1.0

• Improve behavior of wildcard expansion for msvc executable when run from the Windows cmd.exe shell. Unlike in UNIX environments, Windows leaves it up to the executable to expand its own wildcards.

• When reading /P from the encryption dictionary, use static_cast instead of QIntC to convert the value to a signed integer. The value of /P is a bit field, and PDF files have been found in the wild where /P is represented as an unsigned integer even though the spec states that it is a signed 32-bit value. By using static_cast, we allow qpdf to compensate for writers that incorrectly represent the correct bit field as an unsigned value.

• Add support for pluggable crypto providers, enabling multiple implementations of the cryptographic functions needed by qpdf. This feature was added by request of Red Hat, which recognized the use of qpdf's native crypto implementations as a potential security liability, preferring instead to get all crypto functionality from a third-party library that receives a lot of scrutiny. However it was also important to me to not impose any unnecessary third party dependencies on my users or packagers, some of which build qpdf for lots of environments, some of which may not easily support gnutls. Starting in qpdf 9.1.0, it is be possible to build qpdf with both the native and gnutls crypto providers or with either in isolation. In support of this feature, new classes QPDFCryptoProvider and QPDFCryptoImpl have been added to the public interface. See QPDFCryptoImpl.hh for details about adding your own crypto provider and QPDFCryptoProvider.hh for details about choosing which one is used. Note that selection of crypto providers is invisible to anyone who doesn't explicitly care. Neither end users nor developers have to be concerned about it.

• The environment variable QPDF_CRYPTO_PROVIDER can be used to override qpdf's default choice of crypto provider. The --show-crypto flag to the qpdf CLI can be used to present a list of supported crypto providers with the default provider always listed first.

• Add gnutls crypto provider.

• Incorporate changes to properly handle signature in the following ways:
  • Always represent /Contents in a signature dictionary as a hex string
  • Do not compress signature dictionaries when generating object streams
  • Do not encrypt/decrypt the /Contents field of the signature dictionary when creating or reading encrypted files

• Incorporate changes to add additional methods for making it possible to gain deeper insight into cross reference tables and object renumbering. These new API calls make it possible for applications to go into PDF files created by qpdf and make changes to them that go beyond working with the PDF at the object level. The specific use case for these changes was to write an external tool to perform digital signature, but there could be other uses as well. New methods include the following, all of which are described in their respective headers:
  • QPDF::getXRefTable()
  • QPDFObjectHandle::getParsedOffset()
  • QPDFWriter::getRenumberedObjGen(QPDFObjGen)
  • QPDFWriter::getWrittenXRefTable()

[Bruce Dubbs]

Fixed at revision 22383.