“A very serious PGP vulnerability was just discovered. Using
this vulnerability, an attacker can create a modified version of
someone’s public key that will force a sender to encrypt messages
to that person AND to the attacker.“
“Let me explain.”
“When Network Associates joined the Key Recovery Alliance, they
modified PGP to allow for third-party key recovery. They did this
by supporting something called an Additional Decryption Key (ADK).
Normally, when a PGP user creates a PGP certificate, it contains a
single public key (as well as identifying information as to who the
key belongs to). PGP version 5 and 6 allow the user to add
additional ADKs to the certificate. When a sender encrypts a
message to that user, PGP will automatically encrypt the message in
both the user’s public key and the ADK. The idea is that the ADK
belongs to the secret police, or the user’s employer, or some
organization, and that organization can intercept the encrypted
message and read it.”