+#define CHAP_MICROSOFT_V2 0x81 /* use Microsoft-compatible alg. */
+
+/*
+ * Digest type and selection.
+ */
+
+/* bitmask of supported algorithms */
+#define MDTYPE_MICROSOFT_V2 0x1
+#define MDTYPE_MICROSOFT 0x2
+#define MDTYPE_MD5 0x4
+
+#ifdef CHAPMS
+#define MDTYPE_ALL (MDTYPE_MICROSOFT_V2 | MDTYPE_MICROSOFT | MDTYPE_MD5)
+#else
+#define MDTYPE_ALL (MDTYPE_MD5)
+#endif
+#define MDTYPE_NONE 0
+
+/* Return the digest alg. ID for the most preferred digest type. */
+#define CHAP_DIGEST(mdtype) \
+ ((mdtype) & MDTYPE_MICROSOFT_V2)? CHAP_MICROSOFT_V2: \
+ ((mdtype) & MDTYPE_MICROSOFT)? CHAP_MICROSOFT: \
+ ((mdtype) & MDTYPE_MD5)? CHAP_DIGEST_MD5: \
+ 0
+
+/* Return the bit flag (lsb set) for our most preferred digest type. */
+#define CHAP_MDTYPE(mdtype) ((mdtype) ^ ((mdtype) - 1)) & (mdtype)
+
+/* Return the bit flag for a given digest algorithm ID. */
+#define CHAP_MDTYPE_D(digest) \
+ ((digest) == CHAP_MICROSOFT_V2)? MDTYPE_MICROSOFT_V2: \
+ ((digest) == CHAP_MICROSOFT)? MDTYPE_MICROSOFT: \
+ ((digest) == CHAP_DIGEST_MD5)? MDTYPE_MD5: \
+ 0
+
+/* Can we do the requested digest? */
+#define CHAP_CANDIGEST(mdtype, digest) \
+ ((digest) == CHAP_MICROSOFT_V2)? (mdtype) & MDTYPE_MICROSOFT_V2: \
+ ((digest) == CHAP_MICROSOFT)? (mdtype) & MDTYPE_MICROSOFT: \
+ ((digest) == CHAP_DIGEST_MD5)? (mdtype) & MDTYPE_MD5: \
+ 0