📧 Crypto Lab

1. Install Docker Desktop

On Mac:

https://docs.docker.com/desktop/setup/install/mac-install/

On Windows:

https://docs.docker.com/desktop/setup/install/windows-install/

2. Run Debian linux

2.1 Mac

Open the Terminal (Terminal) app and run:

docker run -it debian

2.2 Windows

2.2.1 Instal Terminal app

It is recommended that you install the Terminal app for Windows available at:

https://www.microsoft.com/en-us/p/windows-terminal/9n0dx20hk701

2.2.2 Run

Open the Terminal (Terminal) app and run:

docker run -it debian

2.3 Install OpenSSL

Install the cryptographic library OpenSSL:

apt-get update && apt-get install -y openssl

3. 🔑 Symetric key cryptography

Encrypt and decrypt a plaintext message with symetric key cryptography.

3.1 Plaintext message

3.1.1 Create a message file

Create a file with a message:

echo Attack at 5:00 > message.txt

3.1.2 Read the message file

Read the file with a message:

cat message.txt

3.2 Encryption and decryption

3.2.1 Encrypt message

Encrypt the message:

openssl enc -AES-256-CBC -base64 -pbkdf2 -in message.txt -out encrypted.txt -p -pass pass:password

3.2.2 Show encrypted ciphertext

Show the encrypted ciphertext:

cat encrypted.txt

3.2.3 Decrypt the ciphertext

Decrypt the ciphertext:

openssl enc -AES-256-CBC -base64 -pbkdf2 -in encrypted.txt -out decrypted.txt -p -pass pass:password -d

3.2.4 Show decrypted message

Show the decrypted message:

cat decrypted.txt

4. 🔐 Asymetric (a.k.a. public / private key) cryptography using RSA

Encrypt and decrypt a plaintext message using the RSA (Rivest–Shamir–Adleman) public / private key cryptography.

4.1 Plaintext message

4.1.1 Create a message file

Create a file with a message:

echo Retreat at 6:00 > message.txt

4.1.2 Read the message file

Read the file with a message:

cat message.txt

4.2 Create a RSA key pair

4.2.1 Create a private key

Create a private key:

openssl genpkey -algorithm RSA -out private.txt

4.2.1 View the private key

View the created private key:

cat private.txt

4.2.3 Derive public key

Derive a public key:

openssl rsa -pubout -in private.txt -out public.txt

4.2.4 View the public key

View the created public key:

cat public.txt

4.3 Encryption and decryption

4.3.1 Encrypt message

Encrypt the message using the public key:

openssl pkeyutl -encrypt -pubin -inkey public.txt -in message.txt -out encrypted.bin

4.3.2 Show encrypted ciphertext

Show the encrypted ciphertext:

base64 encrypted.bin

4.3.3 Decrypt the ciphertext

Decrypt the ciphertext using the private key:

openssl pkeyutl -decrypt -inkey private.txt -in encrypted.bin -out decrypted.txt

4.3.4 Show decrypted message

Show the decrypted message:

cat decrypted.txt

5. 🔏Asymetric (a.k.a. public / private key) cryptography using EC

Sign and verify a plaintext message using EC (Elliptic-curve) public / private key cryptography.

5.1 Plaintext message

5.1.1 Create a message file

Create a file with a message:

echo Send 1 million USD to John Smith > message.txt

5.1.2 Read the message file

Read the file with a message:

cat message.txt

5.2 Create a EC key pair

5.2.1 Create a private key

Create a private key:

openssl ecparam -name secp256k1 -genkey -noout -out private.txt

5.2.2 View the private key

View the created private key:

cat private.txt

5.2.3 Derive public key

Derive a public key:

openssl ec -pubout -in private.txt -out public.txt

5.2.4 View the public key

View the created public key:

cat public.txt

5.3 Sign and verify

5.3.1 Sign message

Sign the message using the private key:

openssl dgst -sha256 -sign private.txt -out signature.bin message.txt

5.3.2 Show signature

Show the message signature:

base64 signature.bin

5.3.3 Verify the signature

Verify the signature using the public key:

openssl dgst -sha256 -verify public.txt -signature signature.bin message.txt

5.3.4 Alter message

Alter the message:

echo Send 2 million USD to John Smith > message.txt

5.3.5 Verify the signature again

Verify the signature using the public key:

openssl dgst -sha256 -verify public.txt -signature signature.bin message.txt