Pretty Good Privacy

PGP diagram

Pretty Good Privacy (PGP) is an encryption program that provides cryptographic privacy and authentication for data communication. PGP is used for securing emails, files, directories, and whole disk partitions and to increase the security of email communications. It was created by Phil Zimmermann in 1991.

History

PGP was developed by Phil Zimmermann in 1991. Zimmermann created PGP as a human rights tool to protect the privacy of activists and dissidents. The initial release of PGP was distributed via the Internet and quickly spread worldwide. This led to a legal controversy in the United States because PGP used strong cryptography, which was then classified as munitions and subject to export restrictions.

Functionality

PGP combines features of both symmetric-key cryptography and public-key cryptography. It uses a combination of data compression, hashing, and public-key cryptography to ensure the confidentiality and authenticity of messages.

Symmetric-Key Cryptography

In symmetric-key cryptography, the same key is used for both encryption and decryption. PGP uses a symmetric encryption algorithm to encrypt the plaintext message. The symmetric key is then encrypted with the recipient's public key and sent along with the encrypted message.

Public-Key Cryptography

Public-key cryptography involves a pair of keys: a public key, which can be shared with anyone, and a private key, which is kept secret. PGP uses public-key cryptography to encrypt the symmetric key used for the message encryption. Only the recipient's private key can decrypt the symmetric key, which is then used to decrypt the message.

Digital Signatures

PGP also provides a way to digitally sign a message. A digital signature is created using the sender's private key and can be verified by anyone with access to the sender's public key. This ensures the authenticity and integrity of the message.

Applications

PGP is widely used for securing email communications. It can also be used to encrypt files and directories, ensuring that sensitive data is protected from unauthorized access. PGP has been integrated into various email clients and is also available as standalone software.

Legal Issues

The initial release of PGP led to a legal controversy in the United States. At the time, cryptographic software was classified as munitions and subject to export restrictions. Zimmermann was investigated by the United States Customs Service for allegedly violating export regulations. The investigation was eventually dropped, and PGP was made available worldwide.

Related Pages

• Cryptography
• Public-key cryptography
• Symmetric-key algorithm
• Digital signature
• Phil Zimmermann
• Email encryption

See Also

• GNU Privacy Guard
• OpenPGP
• Encryption software