Add SSH-KDF to cryptography registry (#899)

fixes #898

Author: stevespringett

schema/cryptography-defs.json

@@ -865,6 +865,21 @@
         }
       ]
     },
+    {
+      "family": "SSH-KDF",
+      "standard": [
+        {
+          "name": "RFC4253",
+          "url": "https://doi.org/10.17487/RFC4253"
+        }
+      ],
+      "variant": [
+        {
+          "pattern": "SSH-KDF[-{hashAlgorithm}]",
+          "primitive": "kdf"
+        }
+      ]
+    },
     {
       "family": "TLS-PRF",
       "standard": [