AES-GCM (AES in Galois/Counter Mode) is an authenticated encryption mode that provides both confidentiality (like AES-CBC) and integrity/authenticity (unlike AES-CBC). In AES-GCM, the encryption process produces not only cipher text but also an authentication tag — a short value that any would-be tamperer cannot forge without knowing the key. When decrypting, the recipient verifies the authentication tag before trusting the plaintext. In AES-CBC (the older PDF 1.7 encryption mode), an attacker who modifies cipher text bytes can cause decryption to produce modified plaintext without detection — a property exploited in padding oracle attacks. AES-GCM eliminates this class of attack. PDF 2.0's addition of AES-GCM encryption is primarily relevant for high-security document workflows where tamper detection alongside confidentiality is required.

XFA (XML Forms Architecture) was Adobe's proprietary format for dynamic PDF forms, introduced in LiveCycle Designer. An XFA form embeds XML data streams within a PDF that describe form layout, data binding, and JavaScript-based behaviour. XFA enabled sophisticated dynamic forms that could reflow, grow, and interact with backend systems — capabilities beyond standard AcroForms. However, XFA required Adobe's LiveCycle runtime for full functionality — standard PDF viewers showed only a static rendering. XFA was never part of the ISO 32000 standard (it was referenced normatively in PDF 1.7 but specified in separate Adobe documents). PDF 2.0 deprecated XFA because: it was not interoperable across non-Adobe viewers; it required proprietary Adobe infrastructure; and modern HTML5 forms, properly designed AcroForms, and accessible web-based forms could serve the same purposes with broader compatibility.

An unencrypted wrapper document is a PDF 2.0 feature that allows an encrypted PDF to be wrapped inside an unencrypted container PDF. The wrapper PDF is a fully valid, unencrypted PDF — typically with a cover page explaining that the content is protected. It contains an /EncryptedPayload file specification that references the actual encrypted PDF, which is embedded as a file attachment. The practical benefit: document management systems, search engines, and email gateways can index the wrapper's metadata and cover text (author, title, keywords, document description) without having the decryption key. The encrypted payload is protected, but its existence and basic metadata are discoverable. This architecture is useful for rights-managed documents, secure delivery of sensitive documents to specific recipients, and DRM workflows where document discovery and content protection need to be separated.