Crypto library
Introduction
I allow student to complete programming exercises in their programming language of choice.
I can’t provide examples in all possible programming languages.
Therefore, I want you to write your own code example for how to use various cryptographic functions.
I will provide name and configuration, then you do some research on what libraries or APIs to use in your favorite programming language.
Some functions will be built into the standard library. But others, might require you to search for packages.
You will need to do some research on your own.
Deliverables
I don’t expect you to implement any of the algorithms on your own. Just provide examples using existing implementations.
You will need to submit a PDF document with a code example for each algorithm listed below.
Please include links to resources and libraries you use.
Algorithms
cryptographic random number generator (CRNG)
Provide a code example that use secure random generate to generate a 256 bit value.
This value can be used as encryption key.
You can find some hints here.
Shared-key (symmetric) cipher
Provide and example of using AES-256-GCM or AES-256-CBC to encrypt and decrypt a message.
That is AES (Advanced Encryption Standard) algorithm, with a key size of 256 bit and used in either Galois/counter (GCM) or CBC (Cipher block chaining) mode.
Your example should encrypt a message a decrypt it again.
Use previous code example to generate an encryption key.
You also need an IV, short for initialization vector, also sometimes referred
to as Nonce.
An IV is just a random value generated using a cryptographically secure
pseudorandom number generator (CSPRNG).
The same IV that was use for encryption is also required for decryption.
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You need to generate a new IV for each plain-text that you encrypt. Same IV shall not be used to encrypt multiple times with the same key.
GCM will both produce a cipher-text and an authentication tag. You will need the authentication tag to decrypt.
CBC doesn’t have an authentication tag.
Hashing
Provide an example that uses SHA512 to generate a hash of an input.
That is SHA-2 with a size of 512 bits.
SHA256 is also commonly used, as a side note.
Message Authentication Code (MAC)
Provide an example that have a function to generate a hash-based message authentication (HMAC) using HMAC-SHA256 and a function to verify the HMAC.
You can generate a shared secret using the code from your first example.
Diffie-Hellman key exchange
Provide an example of using Curve25519 ECDH key exchange for two parties to compute the same shared secret.
That is elliptic-curve diffie-Hellman (ECDH) with Curve25519.
Digital signatures
Provide an example of how to use Ed25519 to sign a message and verify its signature.
Ed25519 is short for EdDSA with Curve25519.
RSA (Rivest–Shamir–Adleman)
Provide an example of encrypting with RSA and decrypting.
Key derivation
Provide an example of using PBKDF2-HMAC-SHA512 to derive a key from a password.
That is PBKDF2 (Password-Based Key Derivation Function 2) using HMAC-SHA512 as the underlaying algorithm.
OWASP recommended to use 600,000 iterations.
For password storage I recommend using Argon2id.