What are common OpenSSL commands?

Here are some common OpenSSL commands used for various cryptographic tasks:

1. Generate a Private Key

openssl genrsa -out private.key 2048

2. Generate a Public Key from a Private Key

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

3. Create a Certificate Signing Request (CSR)

openssl req -new -key private.key -out request.csr

4. Generate a Self-Signed Certificate

openssl req -x509 -new -nodes -key private.key -sha256 -days 365 -out certificate.crt

5. View Certificate Details

openssl x509 -in certificate.crt -text -noout

6. Convert Certificate Formats

• PEM to DER:

  openssl x509 -in certificate.crt -outform DER -out certificate.der

• DER to PEM:

  openssl x509 -in certificate.der -inform DER -outform PEM -out certificate.pem

7. Check a Certificate's Validity

openssl verify -CAfile ca.crt certificate.crt

8. Encrypt a File

openssl enc -aes-256-cbc -salt -in plaintext.txt -out encrypted.txt

9. Decrypt a File

openssl enc -d -aes-256-cbc -in encrypted.txt -out decrypted.txt

10. Create a Certificate Authority (CA) Certificate

openssl req -x509 -new -nodes -key private.key -sha256 -days 365 -out ca.crt

Summary:

These commands cover a range of common tasks in OpenSSL, including key generation, certificate management, encryption, and format conversion. If you have further questions or need specific examples, feel free to ask!