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mtlcl410andClaude Opus 5.5
76ae58c8be
Combine refuses to copy an embedded file stream that its source holds encrypted (opened without the password its embedded files need), rather than write that data into another document as the file. An engine test opens and saves such a document through the session, and the parity entry core.attachment-only-encryption records what this covers. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Pq7HyDBXygTf7jcqdsjcfn
79 lines
3.5 KiB
Rust
79 lines
3.5 KiB
Rust
//! A document that encrypts only its embedded files (`/AuthEvent /EFOpen`, ISO 32000-2 §7.6.6,
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//! Table 25), opened without its password, holds them encrypted: combining it into another
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//! document must not copy that data as if it were the files.
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use std::sync::Arc;
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use pdfcraft_cos::{Algorithm, Document, NewEncryption, SaveOptions, write_full};
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use pdfcraft_organize::{OrganizeError, combine};
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/// The password values (`/O`, `/U`, `/OE`, `/UE`, `/Perms`) of an AES-256 (R6) protection with a
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/// user password, as a save writes them.
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fn r6_password_values() -> String {
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let plain = b"%PDF-1.7\n1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj\n2 0 obj << /Type /Pages /Kids [] /Count 0 >> endobj\ntrailer << /Root 1 0 R >>\n%%EOF".to_vec();
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let mut doc = Document::open(Arc::new(plain)).unwrap();
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let params = NewEncryption {
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algorithm: Algorithm::Aes256,
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user_password: "user pw",
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owner_password: "owner pw",
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permissions: -4,
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encrypt_metadata: true,
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seed: [5; 32],
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};
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doc.set_encryption(¶ms).unwrap();
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let saved = Document::open_with_password(Arc::new(write_full(&doc, &SaveOptions::default()).unwrap()), Some("user pw")).unwrap();
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let encrypt = saved.resolve(saved.trailer().get(b"Encrypt").unwrap());
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let encrypt = encrypt.as_dict().unwrap();
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["O", "U", "OE", "UE", "Perms"]
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.iter()
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.map(|k| {
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let value = saved.resolve(encrypt.get(k.as_bytes()).unwrap());
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let hex: String = value.as_string().unwrap().bytes.iter().map(|b| format!("{b:02X}")).collect();
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format!("/{k} <{hex}>")
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})
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.collect::<Vec<_>>()
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.join(" ")
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}
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/// One page in the clear and one attached file encrypted with `/StdCF`, authorised by `/EFOpen`.
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fn efopen_pdf() -> Vec<u8> {
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let encrypt = format!(
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"<< /Filter /Standard /V 5 /R 6 {} /P -4 /CF << /StdCF << /AuthEvent /EFOpen /CFM /AESV3 /Length 32 >> >> /StmF /Identity /StrF /Identity /EFF /StdCF >>",
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r6_password_values()
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);
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let objs = [
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"<< /Type /Catalog /Pages 2 0 R /Names << /EmbeddedFiles << /Names [(note.txt) 4 0 R] >> >> >>".to_string(),
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"<< /Type /Pages /Kids [3 0 R] /Count 1 >>".to_string(),
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"<< /Type /Page /Parent 2 0 R /MediaBox [0 0 200 200] >>".to_string(),
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"<< /Type /Filespec /F (note.txt) /EF << /F 5 0 R >> >>".to_string(),
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"<< /Type /EmbeddedFile /Length 32 >>\nstream\n0123456789abcdef0123456789abcdef\nendstream".to_string(),
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encrypt,
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];
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let mut out = b"%PDF-1.7\n".to_vec();
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let mut offsets = Vec::new();
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for (i, o) in objs.iter().enumerate() {
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offsets.push(out.len());
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out.extend_from_slice(format!("{} 0 obj\n{o}\nendobj\n", i + 1).as_bytes());
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}
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let xref = out.len();
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out.extend_from_slice(format!("xref\n0 {}\n0000000000 65535 f \n", objs.len() + 1).as_bytes());
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for o in offsets {
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out.extend_from_slice(format!("{o:010} 00000 n \n").as_bytes());
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}
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out.extend_from_slice(
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format!("trailer\n<< /Size {} /Root 1 0 R /Encrypt 6 0 R /ID [<00> <00>] >>\nstartxref\n{xref}\n%%EOF\n", objs.len() + 1).as_bytes(),
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);
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out
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}
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#[test]
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fn combining_does_not_copy_attachments_held_encrypted() {
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let src = Document::open(Arc::new(efopen_pdf())).unwrap();
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assert!(src.embedded_files_locked());
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match combine(&[("efopen.pdf", &src)]) {
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Err(OrganizeError::Invalid(why)) => assert!(why.contains("password"), "{why}"),
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Err(other) => panic!("{other}"),
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Ok(_) => panic!("an encrypted attachment was copied as the file"),
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}
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}
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