# OpenSSL

For my SSL keys and certificates I always use:
* `.crt` for the certificates,
* `.key` for the keys and
* `.csr` for the CSRs
While technically not correct I think this is more verbose.

## General commands

* Generate a new private key and Certificate Signing Request

```
openssl req -out signing_request.csr -new -newkey rsa:2048 -nodes -keyout private_key.key
```

* Generate a certificate signing request (CSR) for an existing private key

```
openssl req -out signing_request.csr -key private_key.key -new
```

* Generate a certificate signing request based on an existing certificate

```
openssl x509 -x509toreq -in certificate.crt -out signing_request.csr -signkey private_key.key
```

* Remove a passphrase from a private key

```
openssl rsa -in old_private_key.key -out new_private_key.key
```

## Checking commands


* Check a Certificate Signing Request (CSR)

```
openssl req -text -noout -verify -in signing_request.csr
```

* Check a private key

```
openssl rsa -in private_key.key -check
```

* Check a certificate

```
openssl x509 -in certificate.crt -text -noout
```

* Check a PKCS#12 file (.pfx or .p12)

```
openssl pkcs12 -info -in keystore.p12
```

## Debugging commands

* Compare md5 hashes of certificate, key and CSR

```
openssl x509 -noout -modulus -in certificate.crt | openssl md5
openssl rsa -noout -modulus -in privateKey.key | openssl md5
openssl req -noout -modulus -in CSR.csr | openssl md5
```

* Check an SSL connection. All the certificates (including Intermediates) should be displayed

```
openssl s_client -connect www.paypal.com:443
```