1.1 KiB
1.1 KiB
- #CT255 - Next Generation Technologies II
- Previous Topic: Block Ciphers & Stream Ciphers
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- Relevant Slides:
- There are four types of attacks in the context of communication across a network, which are addressed by message authentication:
- Masquerade (insertion of messages into the network from a fraudulent source).
- Content modification.
- Sequence modification.
- Timing modification (delete or repeat messages).
- Message authentication is concerned with:
- Protecting the integrity of a message.
- Validating the identity of the originator of the message.
- Validating sequencing & timeliness.
- Non-repudiation of origin (dispute resolution).
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Hash Functions
- A hash function is a variation of a MAC, which produces a fixed-size hash code ("fingerprint") based on a variably-sized input message.
- A hash function is public and is not keyed, therefore the hash value must be encrypted.
- Traditional CRCs are too weak and cannot be used.
- 128-512 bit hash values are regarded as suitable.
