msdn link

The SAM_VALIDATE_PASSWORD_HASH structure holds a binary value that represents a cryptographic hash.

 typedef struct _SAM_VALIDATE_PASSWORD_HASH {
   unsigned long Length;
   [unique, size_is(Length)] unsigned char* Hash;
 } SAM_VALIDATE_PASSWORD_HASH,
  *PSAM_VALIDATE_PASSWORD_HASH;

Length: The size, in bytes, of Hash. If zero, Hash MUST be ignored.

Hash: A binary value.