https://pdfsigna.com/blog/ Product news from PDFsigna, and plain-language articles on digital signatures, certificates, PAdES and the five legal levels. en https://pdfsigna.com/blog/how-to-sign-a-pdf-with-a-digital-certificate-on-a-mac/ https://pdfsigna.com/blog/how-to-sign-a-pdf-with-a-digital-certificate-on-a-mac/ Mon, 19 Oct 2026 00:00:00 GMT Digital signatures From a certificate file to a signed PDF: what a signing certificate is, how it gets into the macOS keychain, how to sign with Adobe Acrobat and with PDFsigna, and how to check the signature afterwards. https://pdfsigna.com/blog/preview-breaks-pdf-signatures/ https://pdfsigna.com/blog/preview-breaks-pdf-signatures/ Mon, 19 Oct 2026 00:00:00 GMT Help Preview only places a picture of your signature. Worse, saving a digitally signed PDF from Preview rewrites the file and the signature stops being valid. We measured it on macOS 27: what happens, how to tell, and how to avoid it. https://pdfsigna.com/blog/acrobat-alternatives-you-buy-once/ https://pdfsigna.com/blog/acrobat-alternatives-you-buy-once/ Fri, 16 Oct 2026 00:00:00 GMT Digital signatures Adobe no longer sells a perpetual Acrobat. What it sells instead, which PDF editors still have a one-time price, the four questions to ask before you pay — with every figure checked on the vendor’s own site in October 2026. https://pdfsigna.com/blog/a-visual-signature-is-not-a-digital-signature/ https://pdfsigna.com/blog/a-visual-signature-is-not-a-digital-signature/ Mon, 12 Oct 2026 00:00:00 GMT Digital signatures Your handwriting placed on a PDF is not an advanced electronic signature. What each one is, what it is worth, and how PDFsigna tells you before you sign. https://pdfsigna.com/blog/coming-to-the-mac-app-store-and-the-microsoft-store/ https://pdfsigna.com/blog/coming-to-the-mac-app-store-and-the-microsoft-store/ Mon, 12 Oct 2026 00:00:00 GMT News Where to get PDFsigna, why only there, what it costs, and what isn’t ready yet. https://pdfsigna.com/blog/how-to-check-a-pdf-signature-is-valid/ https://pdfsigna.com/blog/how-to-check-a-pdf-signature-is-valid/ Mon, 12 Oct 2026 00:00:00 GMT Digital signatures Three free ways to validate the signature on a PDF someone sent you — the European Commission’s DSS demo, Spain’s VALIDe and Adobe Acrobat — and what valid, indeterminate, invalid and modified actually mean. https://pdfsigna.com/blog/pades-signature-levels-b-b-b-t-b-lt-b-lta/ https://pdfsigna.com/blog/pades-signature-levels-b-b-b-t-b-lt-b-lta/ Mon, 12 Oct 2026 00:00:00 GMT Digital signatures The four levels of a PAdES signature in plain language: what each one adds, and when it is enough for an agreement, an invoice, or a document someone must still be able to verify in ten years. https://pdfsigna.com/blog/which-certificate-do-you-need-to-sign/ https://pdfsigna.com/blog/which-certificate-do-you-need-to-sign/ Mon, 12 Oct 2026 00:00:00 GMT Certificates Qualified or not, software or smart card: what a signing certificate is, the Spanish options (FNMT, ACCV, the national ID card) explained for everyone, and which ones PDFsigna can use today. https://pdfsigna.com/blog/why-your-signature-needs-a-trusted-timestamp/ https://pdfsigna.com/blog/why-your-signature-needs-a-trusted-timestamp/ Mon, 12 Oct 2026 00:00:00 GMT Digital signatures What a timestamping authority is, why your own computer’s clock proves nothing, and why PDFsigna timestamps signatures with a qualified, free-for-personal-use authority.