Value,Method,Reference
0,Reserved,
1,pre-shared key,[RFC2409]
2,DSS signatures,[RFC2409]
3,RSA signatures,[RFC2409]
4,Encryption with RSA,[RFC2409]
5,Revised encryption with RSA,[RFC2409]
6,Reserved (was Encryption with El-Gamal),
7,Reserved (was Revised encryption with El-Gamal),
8,Reserved (was ECDSA signatures),
9,ECDSA with SHA-256 on the P-256 curve,[RFC4754]
10,ECDSA with SHA-384 on the P-384 curve,[RFC4754]
11,ECDSA with SHA-512 on the P-521 curve,[RFC4754]
12-65000,Unassigned,
65001-65535,Reserved for private use,