Cryptography Protocols Question:

PEM-MIME, also known as MIME Object Security Standard or MOSS, is a proposed Internet Draft [CFG95] that is designed to be a successor to PEM. It proposes adding PEM- based security services to MIME messages in much the same manner as S/MIME. Due to the nature of MIME, it is possible to apply different security services to each part of the body. For example, the MIME body may contain two copies of a message, with one copy digitally signed and the other copy not modified in any way. This will allow a recipient to read the message even if the recipient does not have a MIME-compliant mail reader. If the recipient has a privacy-enhanced MIME compliant mail reader, the recipient will be able to verify the digital signature as well. Another possibility would be to encrypt different blocks of the message body using different keys and algorithms, or to sign some blocks and not others need not b.