OpenSSL CheatSheet

openssl-cheatsheet.sh

# Create X509 self-signed certificate.
openssl req \
    -newkey rsa:2048 -nodes -keyout cert.key \
    -x509 -days 365 -out cert.pem

# Convert from PEM format to DER.
openssl pkcs12 \
    -inkey cert.key -in cert.pem \
    -export -out cert.pfx

# Deserialize public key.
openssl x509 -pubkey -noout -in cert.pem > cert.pub

# Deserialize private key from PKCS#12/PFX.
openssl pkcs12 -in cert.pfx -nocerts

# Create secret data
echo "hello openssl" >> secret.txt

# "Encrypt" with public key. "Decrypt" with private key.
openssl rsautl -encrypt \
    -in secret.txt -out secret.enc \
    -pubin -inkey cert.pub
openssl rsautl -decrypt \
    -in secret.enc -inkey cert.key

# "Sign" with private key. "Verify" with public key.
openssl rsautl -sign \
    -in secret.txt -out secret.sign \
    -inkey cert.key
openssl rsautl -verify \
    -in secret.sign -pubin -inkey cert.pub
    
# hash digest
openssl dgst -md5 -binary -out md5.hash secret.txt # binary
openssl dgst -md5 -binary secret.txt | xxd -p > md5.hash # hex

# HMAC
openssl dgst -sha256 -binary -hmac "rust" -out sha256.hmac secret.txt # binary
openssl dgst -sha256 -binary -hmac "rust" secret.txt | xxd -p > sha256.hmac # hex