Padding flags for asymmetric encryption
PKCS7 Flags/Constants
Predefined Constants
PHP Manual

## Key types

`OPENSSL_KEYTYPE_RSA` (integer)
`OPENSSL_KEYTYPE_DSA` (integer)
`OPENSSL_KEYTYPE_DH` (integer)
`OPENSSL_KEYTYPE_EC` (integer)
  This constant is only available when PHP is compiled with OpenSSL 0.9.8+.

> Note:

> This constant was added in 5.2.0.

> `OPENSSL_KEYTYPE_EC`

Padding flags for asymmetric encryption
PKCS7 Flags/Constants
Predefined Constants
PHP Manual