In this story, we review six products that provide Internet e-mail security. Secret Codes E-mail security relies on encryption. Conventional encryption, called symmetric encryption , uses the same key for encoding and decoding. Phone lines and unencrypted e-mail may not be secure. You could meet your correspondent in the park and hand off the key on a slip of paper, but this is often inconvenient.
Asymmetric encryption eliminates the problem by using two keys, one public and one private.
The sender uses the recipient's public key to encode the message, and the recipient uses his or her private key to decode it. The two keys are mathematically related, but it is virtually impossible to derive the private key from the public key. E-mail security programs keep a private key private by requiring you to enter a password before using it. The asymmetric method eliminates one problem but introduces two new ones. First, you need to find a person's public key to encrypt the message, and second, encryption and decryption by this method are very slow.