Hashing, Signatures & TLS

Hashes · Signatures · Certificates · TLS

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How cryptographic hashes, digital signatures, and the TLS handshake combine to prove what was sent and who sent it.

By the end, you can

List the four properties of a cryptographic hash and explain why each matters.
Describe the avalanche effect and explain why it makes file-integrity checking reliable.
Distinguish cryptographic hashing from hash-table hashing and from encryption.
Explain why passwords need a per-user salt and a slow hash algorithm.
Describe how HMAC works and state its non-repudiation limitation.
Trace the sign-then-verify steps of a digital signature, identifying which key is used at each step.
Explain what non-repudiation is and why digital signatures provide it while HMAC does not.
Describe what a TLS certificate contains and how the chain of trust validates it.
Sequence the six steps of a TLS handshake and explain why ephemeral Diffie-Hellman gives forward secrecy.
State correctly what the browser padlock icon does and does not guarantee.

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