Introduction into Cryptography

The presentation will offer valuable insights into why cryptography matters and how we can use and apply different algorithms in real world scenarios.

Asymmetric Encryption

RSA Algorithm

The RSA (Rivest-Shamir-Adleman) algorithm plays a pivotal role in public-key cryptography. To generate public and private keys using RSA, you can use the following commands:

openssl genrsa -out private-key.pem 2048

To derive a public key from the private key:

openssl rsa -in private-key.pem -pubout -out public-key.pem

You can inspect the RSA algorithm's private and public parameters using:

openssl rsa -in private-key.pem -text -noout

Encrypting data, such as a file named plaintext.txt, with the public key can be done as follows:

openssl pkeyutl -encrypt -in plaintext.txt -out ciphertext -inkey public-key.pem -pubin

Decrypting the data requires the use of the private key:

openssl pkeyutl -decrypt -in ciphertext -inkey private-key.pem -out decrypted.txt

Deffie Hellman key exchange

The Diffie-Hellman key exchange method enables secure communication by establishing shared secret keys. To generate Diffie-Hellman parameters, you can utilize the following command:

openssl dhparam -out dhparams.pem 2045

You can also examine the generated parameters:

openssl dhparam -in dhparams.pem -text -noout

Public Key Infrastructure (PKI)

Public Key Infrastructure is essential for secure online transactions and communication. To create a certificate using RSA encryption, you can employ the following command:

openssl req -new -nodes -newkey rsa:4096 -keyout key.pem -out cert.csr

You can view the certificate data with:

openssl req -in cert.csr -text -noout

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