A digital signature is a cryptographic mechanism used to secure electronic documents and verify identity.
Digital signatures rely on Public Key Infrastructure (PKI). When a document is digitally signed:
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A unique cryptographic hash of the document is created
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The hash is encrypted using the signer’s private key
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The signature can be verified using the corresponding public key
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A digital certificate, issued by a trusted authority, binds the public key to the signer’s identity
This ensures two things:
Identity — the signer can be verified.
Integrity — any change to the document invalidates the signature.
Digital signatures are commonly used in high-assurance environments such as financial services, government systems, healthcare, and cross-border trade where tamper-evidence and non-repudiation are critical.
While digital signatures are often used to implement advanced or qualified electronic signatures under legal frameworks like eIDAS, the technical term “digital signature” refers specifically to the cryptographic method — not the legal classification.