... (with support for 66 curves), RSA (PKCS#1 v2.2 compliant), DSA / DH, DES / 3DES / RC4 / Rijndael / AES / Blowfish / Twofish / Salsa20 / ChaCha20, GCM / Poly1305. The only requirement that phpseclib 3.0 has is that you must be using PHP 5.6+. Using phpseclib2_compat will actually bring a few enhancements to your dependency.