(also digital wrapper, digital envelope encryption)
A digital envelope (or a digital wrapper) is a secure digital data container that protects an electronic message through data authentication and encryption. Digital envelopes are the equivalent of placing a letter into a sealed envelope to make it more secure and resistant to tampering. A digital envelope is encrypted twice using both the secret and public key encryption methods.
Pretty Good Privacy (PGP) encryption. Developed in 1991 by Phil Zimmermann, this popular cryptography software provides privacy and guarantees the authenticity of sent and received data. PGP encryption can encrypt and decrypt emails, text messages, and files or create digital signatures.