For a full list of articles about security, see Overview of security in Acrobat and PDF content.
A digital ID is like an electronic driver’s license or passport that proves your identity. A digital ID usually contains your name and email address, the name of the organization that issued it, a serial number, and an expiration date. Digital IDs are used for certificate security and digital signatures.
Digital IDs contain two keys: the public key locks, or encrypts data; the private key unlocks, or decrypts that data. When you sign PDFs, you use the private key to apply your digital signature. The public key is
You don’t need a digital ID for most of the work you do in PDFs. For example, you don’t need a digital ID to create PDFs, comment on them, and edit them. You need a digital ID to sign a document or encrypt PDFs through a certificate.
You can get a digital ID from a third-party provider, or you can create a self-signed digital ID.
Self-signed digital IDs
Self-signed digital IDs can be adequate for personal use or small-to-medium businesses. Their use should be limited to parties that have established mutual trust.
IDs from certificate authorities
Most business transactions require a digital ID from a trusted third-party provider, called a certificate authority. Because the certificate authority is responsible for verifying your identity to others, choose one that is trusted by major companies doing business on the Internet. The Adobe website gives the names of Adobe security partners that offer digital IDs and other security solutions. See Adobe Approved Trust List members.
Sensitive transactions between businesses generally require an ID from a certificate authority rather than a self-signed one.
New PKCS#12 Digital ID File
Stores the digital ID information in a file, which has the extension .pfx in Windows and .p12 in Mac OS. You can use the files interchangeably between operating systems. If you move a file from one operating system to another, Acrobat still recognizes it.
Type a password for the digital ID file. For each keystroke, the password strength meter evaluates your password and indicates the password strength using color patterns. Reconfirm your password.
You can export and send your certificate file to contacts who can use it to validate your signature.
Make a backup copy of your digital ID file. If your digital ID file is lost or corrupted, or if you forget your password, you cannot use that profile to add signatures.
Select this option if you obtained a digital ID as an electronic file. Follow the prompts to select the digital ID file, type your password, and add the digital ID to the list.
A Roaming Digital ID Stored On A Server
Select this option to use a digital ID that’s stored on a signing server. When prompted, type the server name and URL where the roaming ID is located.
To avoid being prompted to select a digital ID each time your sign or certify a PDF, you can select a default digital ID.
Click the Usage Options button , and choose a task for which you want the digital ID as the default. To specify the digital ID as the default for two tasks, click the Usage Options button again and select
A check mark appears next to selected options. If you select only the signing option, the Sign icon appears next to the digital ID. If you select only the encryption option, the Lock icon appears. If you select only the certifying option, or if you select the signing and certifying options, the Blue Ribbon icon appears.
To clear a default digital ID, repeat these steps, and deselect the usage options you selected.
Passwords and timeouts can be set for PKCS #12 IDs. If the PKCS #12 ID contains multiple IDs, configure the password and timeout at the file level.
Self-signed digital IDs expire in five years. After the expiration date, you can use the ID to open, but not sign or encrypt, a document.
Be sure to back up your password in a secure place. If you lose your password, either create a new self-signed digital ID and delete the old one, or purchase one from a third-party provider.
When you delete a digital ID in Acrobat, you delete the actual PKCS #12 file that contains both the private key and the certificate. Before you delete your digital ID, ensure that it isn’t in use by other programs or required by any documents for decrypting.
You can delete only self-signed digital IDs that you created in Acrobat. A digital ID obtained from another provider cannot be deleted.
By protecting your digital IDs, you can prevent unauthorized use of your private keys for signing or decrypting confidential documents. Ensure that you have a procedure in place in the event your digital ID is lost or stolen.
When private keys are stored on hardware tokens, smart cards, and other hardware devices that are password- or PIN-protected, use a strong password or PIN. Never divulge your password to others. If you must write down your password, store it in a secure location. Contact your system administrator for guidelines on choosing a strong password. Keep your password strong by following these rules:
Use eight or more characters.
Mix uppercase and lowercase letters with numbers and special characters.
Choose a password that is difficult to guess or hack, but that you can remember without having to write it down.
Do not use a correctly spelled word in any language, as they are subject to “dictionary attacks” that can crack these passwords in minutes.
Change your password on a regular basis.
Contact your system administrator for guidelines on choosing a strong password.
To protect private keys stored in P12/PFX files, use a strong password and set your password timeout options appropriately. If using a P12 file to store private keys that you use for signing, use the default setting for password timeout option. This setting ensures that your password is always required. If using your P12 file to store private keys that are used to decrypt documents, make a backup copy of your private key or P12 file. You can use the backed up private key of P12 file to open encrypted documents if you lose your keys.
The mechanisms used to protect private keys stored in the Windows certificate store vary depending on the company that has provided the storage. Contact the provider to determine how to back up and protect these keys from unauthorized access. In general, use the strongest authentication mechanism available and create a strong password or PIN when possible.
If your digital ID was issued by a certificate authority, immediately notify the certificate authority and request the revocation of your certificate. In addition, you should not use your private key.
If your digital ID was self-issued, destroy the private key and notify anyone to whom you sent the corresponding public key (certificate).
A smart card looks like a credit card and stores your digital ID on an embedded microprocessor chip. Use the digital ID on a smart card to sign and decrypt documents on computers that can be connected to a smart card reader. Some smart card readers include a keypad for typing a personal identification number (PIN).
Similarly, a security hardware token is a small, keychain-sized device that you can use to store digital IDs and authentication data. You can access your digital ID by connecting the token to a USB port on your computer or mobile device.
If you store your digital ID on a smart card or hardware token, connect it to your device to use it for signing documents.