openssl keys and cert generation, signed digest generation, verification of signed digest

openssl

# Creating a RSA private key
$ openssl genrsa -out rsaprivkey.pem 1024

# Creating a cert file from priv key
$ openssl req -new -x509 -key rsaprivkey.pem -out rsacert.pem

# Converting from PEM to DER
$ openssl x509 -outform der -in rsacert.pem -out rsacert.der

# Convertin from DER to PEM
$ openssl x509 -inform der -in rsacert.der -out rsacert.pem

# Signing a digest of a file
$ openssl dgst -sha1 -sign rsaprivkey.pem -out file.sig file

# Extracting pub key from cert
$ openssl x509 -pubkey -noout -in rsacert.pem > pubkey.pem

# Verifyig the signature
$ openssl dgst -sha1 -verify pubkey.pem -signature file.sig file

# Getting the fingerpring of the cert, from pem cert
$ openssl x509 -in rsacert.pem -fingerprint -noout
SHA1 Fingerprint=B4:4B:81:58:DA:9A:17:1E:42:54:83:ED:3E:F8:BD:0B:8E:7C:9B:F9

# Getting the fingerprint or the cert, from der (cer)
$ openssl dgst -sha1 rsacert.der
SHA1(rsacert.der)= b44b8158da9a171e425483ed3ef8bd0b8e7c9bf9