Aloaha PDFCrypter seals your PDF with the public key of the recipient. Non PDF files are beeing compressed and PKCS#7 enveloped. No special decryption client needed. Adobe Reader 6 or 7 is enough. Seal PDF Documents secure that they can only be displayed with the right private key.
Ideal solution to sell documents/ebooks online or prohibit re-distribution of confidential documents!
Encryption of non-PDF files and S/MIME Mailer are FREEWARE.
OK, so you want to stamp your document. Maybe you need to give reviewers some advice about the document's status or sensitivity. This tip from author Ted Padova demonstrates how to add stamps with the Stamp Tool along with related comments.