Initializing, please wait a moment

Cach ky mot PDF sau khi xoa mat khau

Mot hop dong den voi mat khau PDF, ban nhap mat khau de mo, nhung PDF tu choi chu ky cua ban vi gioi han mat khau chu so huu. Ban duoc uy quyen ky - nguoi gui da cho ban mat khau - nhung gioi han chinh sua cua PDF chan cong cu ky. Huong dan nay bao quat luong cong viec hop phap: xoa gioi han ma ban duoc phep xoa, ap dung chu ky cua ban, sau do hoac ma hoa lai hoac gui PDF da ky nhu nguoi gui mong doi.


Tai sao dieu nay xay ra - mat khau chu so huu vs nguoi dung

PDF co hai mat khau rieng: mat khau nguoi dung (mo tai lieu) va mat khau chu so huu (cho phep chinh sua, in, ky, hoac sao chep). Nhieu PDF hop dong mo ma khong can mat khau nguoi dung nhung co mat khau chu so huu chan chinh sua. Adobe Reader, Preview va hau het cong cu chu ky ton trong gioi han mat khau chu so huu va tu choi ap dung chu ky ma khong co no. Xem huong dan cac loai mat khau PDF cua chung toi cho co che day du.

Neu nguoi gui da cho ban quyen de ky (va thuong cung da cho ban mat khau chu so huu, hoac PDF khong co mat khau chu so huu duoc dat nhung duoc tao voi gioi han mac dinh), ban co quyen xoa gioi han va ap dung chu ky.


Luong cong viec hop phap

  1. Xac nhan quyen. Gui email hoac hoi nguoi gui: "Toi co duoc uy quyen de ky PDF nay khong?" Cau "co" cua ho la ho so cua ban. Giu lai email.
  2. Xoa gioi han mat khau chu so huu bang cach dung xoa mat khau PDF. No chay trong trinh duyet - PDF khong bao gio duoc tai len. Neu PDF co mat khau chu so huu, nhap vao; neu co gioi han mac dinh ma khong co mat khau duoc dat, cong cu xoa gioi han ngay lap tuc.
  3. Ap dung chu ky cua ban. Hau het cac he dieu hanh co mot cong cu chu ky:
    • macOS: Preview → thanh cong cu Chu thich → bieu tuong Chu ky → ve hoac chup anh chu ky cua ban, sau do bam noi ban muon ap dung.
    • Windows: Adobe Acrobat Reader (mien phi) → Dien va Ky → Tu Ky → Them Chu Ky.
    • iOS: ung dung Files → cham PDF → Markup → cong cu chu ky.
    • Android: Adobe Acrobat Reader mobile → Dien va Ky.
  4. Luu nhu da ky. Dung "Xuat ra PDF" hoac "Luu Mot Ban Sao" - dieu nay lam phang chu ky vao tai lieu.
  5. Tuy chon lam phang PDF voi lam phang PDF de ngan chu ky bi chinh sua hoac di chuyen sau khi ky.
  6. Tuy chon ap dung lai mat khau voi bao ve PDF bang mat khau neu nguoi gui mong doi phien ban da ky duoc bao ve bang mat khau.
  7. Tra lai PDF da ky cho nguoi gui qua email hoac bat ky kenh nao ho chi dinh.

Cac cong cu trong trinh duyet lam gi - va khong lam gi

Cong cu xoa mat khau doc PDF vao tab trinh duyet cua ban, goi rutin decrypt() cua thu vien PDF voi mat khau cua ban, va viet lai PDF da giai ma. Khong gi duoc tai len; khong gi duoc ghi nhat ky. Cong cu co the xu ly PDF duoc bao ve bang mat khau chu so huu, PDF voi gioi han mac dinh, va PDF noi ban biet mat khau nguoi dung. No khong the be khoa mot mat khau khong xac dinh - dieu do khong duoc ho tro va khong hop phap o hau het cac quoc gia.

Cong cu lam phang gop cac ghi chu (chu ky, truong bieu mau, binh luan) vao noi dung trang ben duoi. Sau khi lam phang, chu ky la mot phan vinh vien cua trang; khong ai - bao gom ban - co the di chuyen hoac chinh sua ma khong tao lai toan bo PDF.


Xu ly cac truong hop dac biet

"Da ky va ma hoa" trong mot buoc. Mot so nguoi nhan mong doi PDF tra ve duoc CA hai da ky VA duoc bao ve bang mat khau. Ky truoc (lam phang), sau do ap dung lai mat khau. Cac cong cu PDF tren trang nay noi chuoi sach se: xoa mat khau → ky (offline) → bao ve.

Chu ky chung chi so (PAdES). Mot chu ky ma hoa nhung trong PDF qua mot chung chi ky (tu CA hoac tu ky) manh hon mot chu ky duoc ve. macOS Preview co the ap dung mot chung chi luu Keychain; Acrobat Reader co luong "ID So". Cong cu lam phang trong trinh duyet cua chung toi khong the ap dung PAdES - dieu do yeu cau mot chung chi ky cuc bo va UI ky native.

Chu ky xuat hien nhung canh bao "Tai lieu nay da bi sua doi" hien thi. Mong doi neu PDF goc duoc ky so boi nguoi gui. Xoa mat khau pha vo chu ky so goc (bat ky sua doi nao deu lam). Neu nguoi gui dac biet muon chu ky goc cua ho duoc bao toan, lien lac ho va yeu cau ho gui mot PDF khong bi gioi han de ky.


Can nhac phap ly

Xoa mot mat khau PDF ma ban duoc phep xoa la hop phap o moi quoc gia ma chung toi biet. Xoa mot mat khau ma ban khong duoc phep xoa (bo qua DRM tren mot tai lieu ma ban khong duoc uy quyen chinh sua) co the vi pham luat lam dung may tinh, luat ban quyen, hoac dieu khoan hop dong. Quy tac vang: neu nguoi gui da cho ban mat khau, hoac da uy quyen ro rang cho ban ky, luong xoa-va-ky la hop phap. Neu ban khong chac, hay hoi.

PDF da ky co rang buoc phap ly o hau het cac quoc gia, tuong duong voi mot hop dong da ky tay tren giay. Mot chu ky duoc ve hoac dua tren hinh anh nha chung du cho cac thoa thuan khong nguy hiem; cac hop dong nguy hiem (mua nha, mua lai doanh nghiep, ho so phap ly) ngay cang yeu cau chu ky so duoc ho tro boi chung chi qua DocuSign, Adobe Sign hoac tuong duong.


Rieng tu va cac cong cu trong trinh duyet

Moi buoc trong luong nay chay trong trinh duyet qua cac thu vien PDF WebAssembly. Khong gi duoc tai len; khong gi duoc luu tru; khong gi duoc ghi nhat ky. Dong tab trinh duyet va PDF di. Cho luong cong viec lien quan den tai lieu mat, day la quyen rieng tu manh hon bat ky dich vu PDF dua tren dam may nao.


Cong cu lien quan


← Quay lai Cong Cu PDF

Reviewed by the Free Tool Online editorial team · Tested in the current versions of Chrome, Firefox, Safari, and Edge before publishing. Your file is processed in your browser and never uploaded. Report a bug - we triage within 72 hours. · Last refreshed April 2026.

Why trust these tools

  • Ten-plus years of web tooling. The freetoolonline editorial team has shipped browser-based utilities since 2015. The goal has never changed: get you to a working output fast, without an install.
  • Truly in-browser - no upload. Every file-processing tool on this site runs in your browser through modern Web APIs (File, FileReader, Canvas, Web Audio, WebGL, Web Workers). Your photo, PDF, audio, or text never leaves your device.
  • No tracking during tool use. Analytics ends at the page view. The actual input you paste, drop, or capture is never sent to any server and never written to any log.
  • Open-source core components. The processing engines underneath (libheif, libde265, pdf-lib, terser, clean-css, ffmpeg.wasm, and others) are public and audit-able. We link to each one in its tool page's footer.
  • Free, with or without ads. All tools are fully functional without sign-up. The Disable Ads button in the header is always available if you need a distraction-free run.