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Security Fundamentals & Crypto · Foundational

Digital Signature

Cryptographic value created with a private key over a message hash that proves origin, integrity, and non-repudiation.

Definition

A sender hashes a message and signs the hash with their private key; recipients verify with the sender's public key. A valid signature proves the message came from the private key holder and was not altered. Digital signatures do not provide confidentiality on their own.

Example

Code-signed software lets Windows verify the publisher and detect tampering before installation.

Exam tip

Sign with your private key; verify with the signer's public key. Signatures provide integrity, authentication, and non-repudiation, not confidentiality.

Don't confuse it with

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