| NTLMEngine | Abstract NTLM authentication engine. |
| AuthSchemeBase | Abstract authentication scheme class that serves as a basis for all authentication schemes supported by HttpClient. |
| BasicScheme | Basic authentication scheme as defined in RFC 2617. |
| BasicSchemeFactory | |
| DigestScheme | Digest authentication scheme as defined in RFC 2617. |
| DigestSchemeFactory | |
| NTLMScheme | |
| RFC2617Scheme | Abstract authentication scheme class that lays foundation for all RFC 2617 compliant authetication schemes and provides capabilities common to all authentication schemes defined in RFC 2617. |
| NTLMEngineException | Signals NTLM protocol failure. |
| UnsupportedDigestAlgorithmException | Authentication credentials required to respond to a authentication challenge are invalid |
