Digital signature: Difference between revisions
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'''Digital signatures''' provide [[information security#source authentication|source authentication]] for online documents, messages or records, in a manner analogous to what a signature provides for a paper document. | '''Digital signatures''' provide [[information security#source authentication|source authentication]] for online documents, messages or records, in a manner analogous to what a signature provides for a paper document. | ||
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* calculate a hash or [[message digest]] from the message | * calculate a hash or [[message digest]] from the message | ||
* encrypt that hash with the sender's private key | * encrypt that hash with the sender's private key | ||
* | * combine the encrypted hash with information identifying the signer | ||
* append the combination to the message as a signature | |||
Steps for the receiver are: | Steps for the receiver are: | ||
* obtain the sender's public key and | * obtain the sender's public key and authenticate its integrity and source | ||
* decrypt the signature, using the sender's public key, to get the hash value; call it H<sub>1</sub> | * decrypt the signature, using the sender's public key, to get the hash value; call it H<sub>1</sub> | ||
* hash the message body yourself to get another hash value, H<sub>2</sub> | * hash the message body yourself to get another hash value, H<sub>2</sub> | ||
* compare H<sub>1</sub> and H<sub>2</sub> | * compare H<sub>1</sub> and H<sub>2</sub> | ||
* if they are identical, then you know with overwhelming probability: | * if they are identical, then you know with overwhelming probability (though not with absolute certainty): | ||
** the documents signed (hash | ** the documents signed (hash H<sub>1</sub>) and the document received (hash H<sub>2</sub>) are identical (from properties of a [[cryptographic hash]]) | ||
** whoever generated the signature knew the signer's private key (which only | ** whoever generated the signature knew the signer's private key (which only the signer should know in a [[public key]] system) | ||
* so you can accept the signature as valid | * so you can accept the signature as valid | ||
If both the [[hash (cryptography) | hash]] and the [[public key]] system used are secure, and no-one except the sender knows his private key, then the signatures are trustworthy. | If both the [[hash (cryptography) | hash]] and the [[public key]] system used are secure, and no-one except the sender knows his private key, then the signatures are trustworthy. | ||
The use of digital signatures raises legal issues. There is an online reference <ref>Digital Signature Law Survey https://dsls.rechten.uvt.nl/</ref> for laws around the world. | |||
==References== | |||
{{Reflist|2}}[[Category:Suggestion Bot Tag]] |
Latest revision as of 12:00, 7 August 2024
This article may be deleted soon. | ||
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![]() Digital signatures provide source authentication for online documents, messages or records, in a manner analogous to what a signature provides for a paper document. Two cryptographic techniques are used together to produce a digital signature, a cryptographic hash and a public key cryptosystem. The steps for the sender are as follows:
Steps for the receiver are:
If both the hash and the public key system used are secure, and no-one except the sender knows his private key, then the signatures are trustworthy. The use of digital signatures raises legal issues. There is an online reference [1] for laws around the world. References
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