File Extension SIG
File extension SIG denotes a signature file, and are commonly used in conjunction with popular E-Mail clients such as Microsoft Outlook or QUALCOMM Eudora Pro. SIG files are also used by encryption programs such as Pretty Good Privacy (PGP), and are used to verify the origin of an E-Mail. Though less common, the SIG file extension is also a proprietary image format used by Broderbund graphics software.
The majority of SIG files are small, text files that are either embedded within an E-Mail, or sent as an attachment. They are typically used to store information that a user would wish to send with every E-Mail, such as name, E-Mail address or a favourite quote. E-Mails sent from businesses may also include the company name, address or job title of the sender. Most E-Mail clients can support multiple SIG files, allowing the user can specify which signature(s) to attach when composing an E-Mail.
SIG files are also used in conjunction with encryption software such as PGP. These applications generate a hash from the text of the E-Mail along with a digital signature from this hash using the sender's private key. This will then be typically attached to the E-Mail as a SIG attachment, or as plaintext at the bottom of the E-Mail. This signature can be used by the recipient with the same software and the sender's public key to verify that the E-Mail has not been altered since it was sent and that it actually came from the specified sender.
SIG signature files can be opened using appropriate E-Mail clients such as Microsoft Outlook, Outlook Express or QUALCOMM Eudora Pro. SIG files are also used by privacy and security software to check the integrity and origin of E-Mails, and so can be used by a recipient to confirm these details. SIG image files can be opened using appropriate versions of Broderbund software such as PrintMaster or The Print Shop.