File containing a digital certificate that uses PKCS#12 (Public Key Cryptography Standard #12) encryption; used as a portable format for transferring personal private keys or other sensitive information; used by various security and encryption programs. P12 keys store a private key that can encrypt information which can only be decrypted by the corresponding public key. Likewise, data encrypted with the public key can only be decrypted by the private key. This helps validate the source of transmitted information.