Key Format:
RSA Public Key
-----BEGIN RSA PUBLIC KEY-----
-----END RSA PUBLIC KEY-----
Encrypted Private Key
-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
-----END RSA PRIVATE KEY-----
CRL
-----BEGIN X509 CRL-----
-----END X509 CRL-----
CRT
-----BEGIN CERTIFICATE-----
-----END CERTIFICATE-----
CSR
-----BEGIN CERTIFICATE REQUEST-----
-----END CERTIFICATE REQUEST-----
NEW CSR
-----BEGIN NEW CERTIFICATE REQUEST-----
-----END NEW CERTIFICATE REQUEST-----
PEM
-----BEGIN RSA PRIVATE KEY-----
-----END RSA PRIVATE KEY-----
PKCS7
-----BEGIN PKCS7-----
-----END PKCS7-----
PRIVATE KEY
-----BEGIN PRIVATE KEY-----
-----END PRIVATE KEY-----
DSA KEY
-----BEGIN DSA PRIVATE KEY-----
-----END DSA PRIVATE KEY-----
Elliptic Curve
-----BEGIN EC PRIVATE KEY-----
-----END EC PRIVATE KEY-----
PGP Private Key
-----BEGIN PGP PRIVATE KEY BLOCK-----
-----END PGP PRIVATE KEY BLOCK-----
PGP Public Key
-----BEGIN PGP PUBLIC KEY BLOCK-----
-----END PGP PUBLIC KEY BLOCK-----Check Key
openssl asn1parse -i -in a.pem
Convert PKCS8 key to ssh-rsa format
ssh-keygen -f a.pub -i -m PKCS8