How Digital Signatures Work

Digital signatures are a special form of encryption used for verifying the authenticity of some piece of data. Although a digital signature is a form of encryption, it doesn't mean that data itself is encrypted. In other words, digitally signed data is not encrypted—or rather, it doesn't need to be encrypted. There is nothing to stop you from encrypting the data as an additional step.

When you use digital signatures, you deal with three items: the original data, the digital signature, and the public key of the signer. Of course, if you need the public key of the signer, you can bet that the signer's private key enters into the mixture, too. Figure 34.1 shows the basic sequence in signing a document and verifying the ...

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