Merge lorikeet-heimdal -r 787 into Samba4 tree.

Andrew Bartlett
(This used to be commit d88b530522d3cef67c24422bd5182fb875d87ee2)

1 files changed, 206 insertions, 9 deletions

diff --git a/source4/heimdal/lib/hcrypto/dh.c b/source4/heimdal/lib/hcrypto/dh.c
index b558eb901c..9f1af0b3b1 100644
--- a/source4/heimdal/lib/hcrypto/dh.c
+++ b/source4/heimdal/lib/hcrypto/dh.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2006 Kungliga Tekniska Högskolan
+ * Copyright (c) 2006 - 2007 Kungliga Tekniska Högskolan
  * (Royal Institute of Technology, Stockholm, Sweden). 
  * All rights reserved. 
  *
@@ -35,7 +35,7 @@
 #include <config.h>
 #endif
 
-RCSID("$Id: dh.c 18618 2006-10-19 17:31:51Z lha $");
+RCSID("$Id: dh.c 22397 2008-01-01 20:20:31Z lha $");
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -43,8 +43,23 @@ RCSID("$Id: dh.c 18618 2006-10-19 17:31:51Z lha $");
 
 #include <roken.h>
 
-/*
+/**
+ * @page page_dh DH - Diffie-Hellman key exchange
+ *
+ * Diffie-Hellman key exchange is a protocol that allows two parties
+ * to establish a shared secret key.
+ *
+ * Include and example how to use DH_new() and friends here.
  *
+ * See the library functions here: @ref hcrypto_dh
+ */
+
+/**
+ * Create a new DH object using DH_new_method(NULL), see DH_new_method().
+ *
+ * @return a newly allocated DH object.
+ *
+ * @ingroup hcrypto_dh
  */
 
 DH *
@@ -53,6 +68,17 @@ DH_new(void)
     return DH_new_method(NULL);
 }
 
+/**
+ * Create a new DH object from the given engine, if the NULL is used,
+ * the default engine is used. Free the DH object with DH_free().
+ *
+ * @param engine The engine to use to allocate the DH object. 
+ *
+ * @return a newly allocated DH object.
+ *
+ * @ingroup hcrypto_dh
+ */
+
 DH *
 DH_new_method(ENGINE *engine)
 {
@@ -88,6 +114,15 @@ DH_new_method(ENGINE *engine)
     return dh;
 }
 
+/**
+ * Free a DH object and release related resources, like ENGINE, that
+ * the object was using.
+ *
+ * @param dh object to be freed.
+ *
+ * @ingroup hcrypto_dh
+ */
+
 void
 DH_free(DH *dh)
 {
@@ -116,18 +151,52 @@ DH_free(DH *dh)
     free(dh);
 }    
 
+/**
+ * Add a reference to the DH object. The object should be free with
+ * DH_free() to drop the reference.
+ *
+ * @param dh the object to increase the reference count too.
+ *
+ * @return the updated reference count, can't safely be used except
+ * for debug printing.
+ * 
+ * @ingroup hcrypto_dh
+ */
+
 int
 DH_up_ref(DH *dh)
 {
     return ++dh->references;
 }
 
+/**
+ * The maximum output size of the DH_compute_key() function.
+ *
+ * @param dh The DH object to get the size from.
+ *
+ * @return the maximum size in bytes of the out data.
+ *
+ * @ingroup hcrypto_dh
+ */
+
 int
 DH_size(const DH *dh)
 {
     return BN_num_bytes(dh->p);
 }
 
+/**
+ * Set the data index idx in the DH object to data.
+ *
+ * @param dh DH object.
+ * @param idx index to set the data for.
+ * @param data data to store for the index idx.
+ *
+ * @return 1 on success.
+ *
+ * @ingroup hcrypto_dh
+ */
+
 int
 DH_set_ex_data(DH *dh, int idx, void *data)
 {
@@ -135,12 +204,36 @@ DH_set_ex_data(DH *dh, int idx, void *data)
     return 1;
 }
 
+/**
+ * Get the data for index idx in the DH object.
+ *
+ * @param dh DH object.
+ * @param idx index to get the data for.
+ *
+ * @return the object store in index idx
+ *
+ * @ingroup hcrypto_dh
+ */
+
 void *
 DH_get_ex_data(DH *dh, int idx)
 {
     return dh->ex_data.sk;
 }
 
+/**
+ * Generate DH parameters for the DH object give parameters.
+ *
+ * @param dh The DH object to generate parameters for.
+ * @param prime_len length of the prime
+ * @param generator generator, g
+ * @param cb Callback parameters to show progress, can be NULL.
+ *
+ * @return the maximum size in bytes of the out data.
+ *
+ * @ingroup hcrypto_dh
+ */
+
 int
 DH_generate_parameters_ex(DH *dh, int prime_len, int generator, BN_GENCB *cb)
 {
@@ -149,12 +242,17 @@ DH_generate_parameters_ex(DH *dh, int prime_len, int generator, BN_GENCB *cb)
     return 0;
 }
 
-/*
- * Check that
+/**
+ * Check that the public key is sane.
  *
- * 	pub_key > 1    and    pub_key < p - 1
+ * @param dh the local peer DH parameters.
+ * @param pub_key the remote peer public key parameters.
+ * @param codes return that the failures of the pub_key are.
  *
- * to avoid small subgroups attack.
+ * @return 1 on success, 0 on failure and *codes is set the the
+ * combined fail check for the public key
+ *
+ * @ingroup hcrypto_dh
  */
 
 int
@@ -165,6 +263,19 @@ DH_check_pubkey(const DH *dh, const BIGNUM *pub_key, int *codes)
 
     *codes = 0;
 
+    /**
+     * Checks that the function performs are:
+     * - pub_key is not negative 
+     */
+
+    if (BN_is_negative(pub_key))
+	goto out;
+
+    /**
+     * - pub_key > 1    and    pub_key < p - 1,
+     *    to avoid small subgroups attack.
+     */
+
     bn = BN_new();
     if (bn == NULL)
 	goto out;
@@ -184,6 +295,28 @@ DH_check_pubkey(const DH *dh, const BIGNUM *pub_key, int *codes)
     if (BN_cmp(sum, dh->p) >= 0)
 	*codes |= DH_CHECK_PUBKEY_TOO_LARGE;
 
+    /**
+     * - if g == 2, pub_key have more then one bit set,
+     *   if bits set is 1, log_2(pub_key) is trival
+     */
+
+    if (!BN_set_word(bn, 2))
+	goto out;
+
+    if (BN_cmp(bn, pub_key) == 0) {
+	unsigned i, n = BN_num_bits(pub_key);
+	unsigned bits = 0;
+
+	for (i = 0; i <= n; i++)
+	    if (BN_is_bit_set(pub_key, i))
+		bits++;
+
+	if (bits > 1) {
+	    *codes |= DH_CHECK_PUBKEY_TOO_SMALL;
+	    goto out;
+	}
+    }
+
     ret = 1;
 out:
     if (bn)
@@ -194,24 +327,64 @@ out:
     return ret;
 }
 
+/**
+ * Generate a new DH private-public key pair. The dh parameter must be
+ * allocted first with DH_new(). dh->p and dp->g must be set.
+ *
+ * @param dh dh parameter.
+ *
+ * @return 1 on success.
+ *
+ * @ingroup hcrypto_dh
+ */
+
 int
 DH_generate_key(DH *dh)
 {
     return dh->meth->generate_key(dh);
 }
 
+/**
+ * Complute the shared secret key.
+ *
+ * @param shared_key the resulting shared key, need to be at least
+ * DH_size() large.
+ * @param peer_pub_key the peer's public key.
+ * @param dh the dh key pair.
+ *
+ * @return 1 on success.
+ *
+ * @ingroup hcrypto_dh
+ */
+
 int
 DH_compute_key(unsigned char *shared_key,
 	       const BIGNUM *peer_pub_key, DH *dh)
 {
     int codes;
 
+    /**
+     * Checks that the pubkey passed in is valid using
+     * DH_check_pubkey().
+     */
+
     if (!DH_check_pubkey(dh, peer_pub_key, &codes) || codes != 0)
 	return -1;
 
     return dh->meth->compute_key(shared_key, peer_pub_key, dh);
 }
 
+/**
+ * Set a new method for the DH keypair.
+ *
+ * @param dh dh parameter.
+ * @param method the new method for the DH parameter.
+ *
+ * @return 1 on success.
+ *
+ * @ingroup hcrypto_dh
+ */
+
 int
 DH_set_method(DH *dh, const DH_METHOD *method)
 {
@@ -271,8 +444,16 @@ static const DH_METHOD dh_null_method = {
     dh_null_generate_params
 };
 
-extern const DH_METHOD hc_dh_imath_method;
-static const DH_METHOD *dh_default_method = &hc_dh_imath_method;
+extern const DH_METHOD _hc_dh_imath_method;
+static const DH_METHOD *dh_default_method = &_hc_dh_imath_method;
+
+/**
+ * Return the dummy DH implementation.
+ *
+ * @return pointer to a DH_METHOD.
+ *
+ * @ingroup hcrypto_dh
+ */
 
 const DH_METHOD *
 DH_null_method(void)
@@ -280,12 +461,28 @@ DH_null_method(void)
     return &dh_null_method;
 }
 
+/**
+ * Set the default DH implementation.
+ *
+ * @param meth pointer to a DH_METHOD.
+ *
+ * @ingroup hcrypto_dh
+ */
+
 void
 DH_set_default_method(const DH_METHOD *meth)
 {
     dh_default_method = meth;
 }
 
+/**
+ * Return the default DH implementation.
+ *
+ * @return pointer to a DH_METHOD.
+ *
+ * @ingroup hcrypto_dh
+ */
+
 const DH_METHOD *
 DH_get_default_method(void)
 {