A public key infrastructure (PKI) is an arrangement that binds public keys with respective identities of entities (like people and organizations). The binding is established through a process of registration and issuance of certificates by a certificate authority (CA). The primary role of the CA is to digitally sign and publish the public key bound to a given user. This is done using the CA's own private key, so that trust in the user key relies on one's trust in the validity of the CA's key.
Consider a mixed encryption scheme, which combines asymmetric key scheme with symmetric key scheme. We can define a mixed encryption scheme for transmitting a message m from user P to user Q, as follows:
- m := message
- k := key of symmetric key scheme
- skP := secret key for user P
- pkP := public key for user P
- skQ := secret key for user Q
- pkQ := public key for user Q
- ES := Encryption algorithm for symmetric key scheme
- DS := Decryption algorithm for symmetric key scheme
- EA := Encryption algorithm for asymmetric key scheme
- DA := Decryption algorithm for asymmetric key scheme
- cs ← ES(m, k)
- (c, k') ← EA(DA((cs, k), skP), pkQ)
- (cs, k) ← EA(DA((c, k'), skQ), pkP)
- m ← DS(cs, k)
In this project, RSA has been used as asymmetric key scheme and Vigenere as symmetric key scheme.
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GNU Multiple Precision Arithmetic Library
apt-get install libgmp-dev
make./rsa < <file_containing_message>./rsa < input.txtmake clean