Introduction to Information Security

partners, but in the end that might not be enough.
★ Threats:
○ compromise of confidentiality of secret keys
○ compromise of authenticity of secret or public keys.
○ unauthorized use of public or secret keys
Why are we talking about key management?
• Key predistribution
– All keying material issued in advance on
initialisation of the system
• Key distribution
– “Trusted” entity involved in establishment of
keys
• Key agreement
– Communicating parties jointly establish keys
Key establishment
• Each bit of the key should depend on each
component
• No person is ever in possession of more than one
component
• Components should be stored in separate locations
Manual key establishment
• Name of owner
– could be a person, device, or even role.
– Should uniquely identify the owner within the environment in which
the public key will be employed.
• Public key value
• Validity time period
– identifies date and time from which the public key is valid, and more
importantly the date and time of its expiry.
• Signature
– Creator of certificate digitally signs all data that forms the public key
certificate. This binds the data and acts as a guarantee that the
creator of the certificate believes the data is correct.
Public key certificates

Computer Systems Security

Digital signature and electronic signature

What Is An Electronic Signature?

• An“electronic signature” consists of some string of symbols or characters manifested by electronic means, executed by a party with an intent to authenticate a writing. Examples: the sender’s name typed at the end of an e-mail message, a digital image of a handwritten signature attached to an electronic document, a PIN number, and so on.
• The expression ‘digital signature’ is usually used to refer to a special kind of electronic signature.