1 files changed, 93 insertions, 0 deletions
diff --git a/usr.bin/ssh/mpaux.c b/usr.bin/ssh/mpaux.c
new file mode 100644
index 00000000000..78ff1f93d68
--- /dev/null
+++ b/usr.bin/ssh/mpaux.c
@@ -0,0 +1,93 @@
+/*
+
+mpaux.c
+
+Author: Tatu Ylonen <ylo@cs.hut.fi>
+
+Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+                   All rights reserved
+
+Created: Sun Jul 16 04:29:30 1995 ylo
+
+This file contains various auxiliary functions related to multiple
+precision integers.
+
+*/
+
+#include "includes.h"
+RCSID("$Id: mpaux.c,v 1.1 1999/09/26 20:53:36 deraadt Exp $");
+
+#include <gmp.h>
+#include "getput.h"
+#include "xmalloc.h"
+#include "ssh_md5.h"
+
+/* Converts a multiple-precision integer into bytes to be stored in the buffer.
+   The buffer will contain the value of the integer, msb first. */
+
+void mp_linearize_msb_first(unsigned char *buf, unsigned int len, 
+			    MP_INT *value)
+{
+  unsigned int i;
+  MP_INT aux;
+  mpz_init_set(&aux, value);
+  for (i = len; i >= 4; i -= 4)
+    {
+      unsigned int limb = mpz_get_ui(&aux);
+      PUT_32BIT(buf + i - 4, limb);
+      mpz_div_2exp(&aux, &aux, 32);
+    }
+  for (; i > 0; i--)
+    {
+      buf[i - 1] = mpz_get_ui(&aux);
+      mpz_div_2exp(&aux, &aux, 8);
+    }
+  mpz_clear(&aux);
+}
+
+/* Extract a multiple-precision integer from buffer.  The value is stored
+   in the buffer msb first. */
+
+void mp_unlinearize_msb_first(MP_INT *value, const unsigned char *buf,
+			      unsigned int len)
+{
+  unsigned int i;
+  mpz_set_ui(value, 0);
+  for (i = 0; i + 4 <= len; i += 4)
+    {
+      unsigned int limb = GET_32BIT(buf + i);
+      mpz_mul_2exp(value, value, 32);
+      mpz_add_ui(value, value, limb);
+    }
+  for (; i < len; i++)
+    {
+      mpz_mul_2exp(value, value, 8);
+      mpz_add_ui(value, value, buf[i]);
+    }
+}
+
+/* Computes a 16-byte session id in the global variable session_id.
+   The session id is computed by concatenating the linearized, msb
+   first representations of host_key_n, session_key_n, and the cookie. */
+
+void compute_session_id(unsigned char session_id[16],
+			unsigned char cookie[8],
+			unsigned int host_key_bits,
+			MP_INT *host_key_n,
+			unsigned int session_key_bits,
+			MP_INT *session_key_n)
+{
+  unsigned int bytes = (host_key_bits + 7) / 8 + (session_key_bits + 7) / 8 + 8;
+  unsigned char *buf = xmalloc(bytes);
+  struct MD5Context md;
+  
+  mp_linearize_msb_first(buf, (host_key_bits + 7 ) / 8, host_key_n);
+  mp_linearize_msb_first(buf + (host_key_bits + 7 ) / 8, 
+			 (session_key_bits + 7) / 8, session_key_n);
+  memcpy(buf + (host_key_bits + 7) / 8 + (session_key_bits + 7) / 8,
+	 cookie, 8);
+  MD5Init(&md);
+  MD5Update(&md, buf, bytes);
+  MD5Final(session_id, &md);
+  xfree(buf);
+}