An organisation transmits a highly confidential contract over a public network. To protect the transmission, they must guarantee both confidentiality (so eavesdroppers cannot read the contract) and non-repudiation (proving the contract was sent by Sender S S\,S and has not been altered).
Which of the following describes the correct sequence of cryptographic operations performed by Sender S S\,S and Receiver R R\,R using asymmetric key pairs SprivateS_{\text{private}}Sprivate / SpublicS_{\text{public}}Spublic and RprivateR_{\text{private}}Rprivate / RpublicR_{\text{public}}Rpublic?
Sender SSS encrypts the contract's hash using SprivateS_{\text{private}}Sprivate to create a digital signature, and encrypts both the contract and signature using RpublicR_{\text{public}}Rpublic. Receiver RRR decrypts using RprivateR_{\text{private}}Rprivate, and decrypts the signature using SpublicS_{\text{public}}Spublic to verify the hash.
Sender SSS encrypts the contract's hash using RpublicR_{\text{public}}Rpublic to create a digital signature, and encrypts both the contract and signature using SprivateS_{\text{private}}Sprivate. Receiver RRR decrypts using SpublicS_{\text{public}}Spublic, and decrypts the signature using RprivateR_{\text{private}}Rprivate to verify the hash.
Sender SSS encrypts the contract's hash using SprivateS_{\text{private}}Sprivate to create a digital signature, and encrypts both the contract and signature using SpublicS_{\text{public}}Spublic. Receiver RRR decrypts using SprivateS_{\text{private}}Sprivate, and decrypts the signature using RpublicR_{\text{public}}Rpublic to verify the hash.
Sender SSS encrypts the contract's hash using RprivateR_{\text{private}}Rprivate to create a digital signature, and encrypts both the contract and signature using RpublicR_{\text{public}}Rpublic. Receiver RRR decrypts using RprivateR_{\text{private}}Rprivate, and decrypts the signature using RpublicR_{\text{public}}Rpublic to verify the hash.
Practise Edexcel GCSE Computer Science Cybersecurity with exam-style questions for GCSE Computer Science. 41 questions covering Malware threats and cyberattack methods and Protecting digital systems and data, matched to the Edexcel GCSE Computer Science (1CP2) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.