Major new upstream release, just ran svn-upgrade for now (and wrote some

debian/changelong entries).

6 files changed, 733 insertions, 0 deletions

diff --git a/src/libstrongswan/crypto/prfs/fips_prf.c b/src/libstrongswan/crypto/prfs/fips_prf.c
new file mode 100644
index 000000000..0ab80b089
--- /dev/null
+++ b/src/libstrongswan/crypto/prfs/fips_prf.c
@@ -0,0 +1,258 @@
+/**
+ * @file fips_prf.c
+ * 
+ * @brief Implementation for fips_prf_t.
+ * 
+ */
+
+/*
+ * Copyright (C) 2006 Martin Willi
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "fips_prf.h"
+
+#include <arpa/inet.h>
+
+#include <debug.h>
+
+typedef struct private_fips_prf_t private_fips_prf_t;
+
+/**
+ * Private data of a fips_prf_t object.
+ */
+struct private_fips_prf_t {
+	/**
+	 * Public fips_prf_t interface.
+	 */
+	fips_prf_t public;
+	
+	/**
+	 * key of prf function, "b" long
+	 */
+	u_int8_t *key;
+	
+	/**
+	 * size of "b" in bytes
+	 */
+	size_t b;
+	
+	/**
+	 * G function, either SHA1 or DES
+	 */
+	void (*g)(u_int8_t t[], chunk_t c, u_int8_t res[]);
+};
+
+/**
+ * t used in G(), equals to initial SHA1 value
+ */
+static u_int8_t t[] = {
+	0x67,0x45,0x23,0x01,0xEF,0xCD,0xAB,0x89,0x98,0xBA,
+	0xDC,0xFE,0x10,0x32,0x54,0x76,0xC3,0xD2,0xE1,0xF0,
+};
+
+/**
+ * sum = (a + b) mod 2 ^ (length * 8)
+ */
+static void add_mod(size_t length, u_int8_t a[], u_int8_t b[], u_int8_t sum[])
+{
+	int i, c = 0;
+	
+	for(i = length - 1; i >= 0; i--)
+	{
+		u_int32_t tmp;
+		
+		tmp = a[i] + b[i] + c;
+		sum[i] = 0xff & tmp;
+		c = tmp >> 8;
+	}
+}
+
+/**
+ * calculate "chunk mod 2^(length*8)" and save it into buffer
+ */
+static void chunk_mod(size_t length, chunk_t chunk, u_int8_t buffer[])
+{
+	if (chunk.len < length)
+	{
+		/* apply seed as least significant bits, others are zero */
+		memset(buffer, 0, length - chunk.len);
+		memcpy(buffer + length - chunk.len, chunk.ptr, chunk.len);
+	}
+	else
+	{
+		/* use least significant bytes from seed, as we use mod 2^b */
+		memcpy(buffer, chunk.ptr + chunk.len - length, length);
+	}
+}
+
+/**
+ * Implementation of prf_t.get_bytes.
+ *
+ * Test vector:
+ *
+ * key:
+ * 0xbd, 0x02, 0x9b, 0xbe, 0x7f, 0x51, 0x96, 0x0b,
+ * 0xcf, 0x9e, 0xdb, 0x2b, 0x61, 0xf0, 0x6f, 0x0f,
+ * 0xeb, 0x5a, 0x38, 0xb6
+ *
+ * seed:
+ * 0x00
+ *
+ * result:
+ * 0x20, 0x70, 0xb3, 0x22, 0x3d, 0xba, 0x37, 0x2f,
+ * 0xde, 0x1c, 0x0f, 0xfc, 0x7b, 0x2e, 0x3b, 0x49,
+ * 0x8b, 0x26, 0x06, 0x14, 0x3c, 0x6c, 0x18, 0xba,
+ * 0xcb, 0x0f, 0x6c, 0x55, 0xba, 0xbb, 0x13, 0x78,
+ * 0x8e, 0x20, 0xd7, 0x37, 0xa3, 0x27, 0x51, 0x16
+ */
+static void get_bytes(private_fips_prf_t *this, chunk_t seed, u_int8_t w[])
+{
+	int i;
+	u_int8_t xval[this->b];
+	u_int8_t xseed[this->b];
+	u_int8_t sum[this->b];
+	u_int8_t *xkey = this->key;
+	u_int8_t one[this->b];
+	chunk_t xval_chunk = chunk_from_buf(xval);
+	
+	memset(one, 0, this->b);
+	one[this->b - 1] = 0x01;
+	
+	/* 3.1 */
+	chunk_mod(this->b, seed, xseed);
+	
+	/* 3.2 */
+	for (i = 0; i < 2; i++) /* twice */
+	{
+		/* a. XVAL = (XKEY + XSEED j) mod 2^b */
+		add_mod(this->b, xkey, xseed, xval);
+		DBG3("XVAL %b", xval, this->b);
+		/* b. wi = G(t, XVAL ) */
+		this->g(t, xval_chunk, &w[i * this->b]);
+		DBG3("w[%d] %b", i, &w[i * this->b], this->b);
+		/* c. XKEY = (1 + XKEY + wi) mod 2b */
+		add_mod(this->b, xkey, &w[i * this->b], sum);
+		add_mod(this->b, sum, one, xkey);
+		DBG3("XKEY %b", xkey, this->b);
+	}
+	
+	/* 3.3 done already, mod q not used */
+}
+
+/**
+ * Implementation of prf_t.get_block_size.
+ */
+static size_t get_block_size(private_fips_prf_t *this)
+{
+	return 2 * this->b;
+}
+/**
+ * Implementation of prf_t.allocate_bytes.
+ */
+static void allocate_bytes(private_fips_prf_t *this, chunk_t seed, chunk_t *chunk)
+{
+	*chunk = chunk_alloc(get_block_size(this));
+	get_bytes(this, seed, chunk->ptr);
+}
+
+/**
+ * Implementation of prf_t.get_key_size.
+ */
+static size_t get_key_size(private_fips_prf_t *this)
+{
+	return this->b;
+}
+
+/**
+ * Implementation of prf_t.set_key.
+ */
+static void set_key(private_fips_prf_t *this, chunk_t key)
+{
+	/* save key as "key mod 2^b" */
+	chunk_mod(this->b, key, this->key);
+}
+
+/**
+ * Implementation of the G() function based on SHA1
+ */
+void g_sha1(u_int8_t t[], chunk_t c, u_int8_t res[])
+{
+	hasher_t *hasher;
+	u_int8_t buf[64];
+	chunk_t state_chunk;
+	u_int32_t *state, *iv, *hash;
+	
+	if (c.len < sizeof(buf))
+	{
+		/* pad c with zeros */
+		memset(buf, 0, sizeof(buf));
+		memcpy(buf, c.ptr, c.len);
+		c.ptr = buf;
+		c.len = sizeof(buf);
+	}
+	else
+	{
+		/* not more than 512 bits can be G()-ed */
+		c.len = sizeof(buf);
+	}
+	
+	/* our SHA1 hasher's state is 32-Bit integers in host order. We must
+	 * convert them */
+	hasher = hasher_create(HASH_SHA1);
+	state_chunk = hasher->get_state(hasher);
+	state = (u_int32_t*)state_chunk.ptr;
+	iv = (u_int32_t*)t;
+	hash = (u_int32_t*)res;
+	state[0] = htonl(iv[0]);
+	state[1] = htonl(iv[1]);
+	state[2] = htonl(iv[2]);
+	state[3] = htonl(iv[3]);
+	hasher->get_hash(hasher, c, NULL);
+	hash[0] = htonl(state[0]);
+	hash[1] = htonl(state[1]);
+	hash[2] = htonl(state[2]);
+	hash[3] = htonl(state[3]);
+	hash[4] = htonl(state[4]);
+	hasher->destroy(hasher);
+}
+
+/**
+ * Implementation of prf_t.destroy.
+ */
+static void destroy(private_fips_prf_t *this)
+{
+	free(this->key);
+	free(this);
+}
+
+/*
+ * Described in header.
+ */
+fips_prf_t *fips_prf_create(size_t b, void(*g)(u_int8_t[],chunk_t,u_int8_t[]))
+{
+	private_fips_prf_t *this = malloc_thing(private_fips_prf_t);
+	
+	this->public.prf_interface.get_bytes = (void (*) (prf_t *,chunk_t,u_int8_t*))get_bytes;
+	this->public.prf_interface.allocate_bytes = (void (*) (prf_t*,chunk_t,chunk_t*))allocate_bytes;
+	this->public.prf_interface.get_block_size = (size_t (*) (prf_t*))get_block_size;
+	this->public.prf_interface.get_key_size = (size_t (*) (prf_t*))get_key_size;
+	this->public.prf_interface.set_key = (void (*) (prf_t *,chunk_t))set_key;
+	this->public.prf_interface.destroy = (void (*) (prf_t *))destroy;
+	
+	this->g = g;
+	this->b = b;
+	this->key = malloc(b);
+	
+	return &(this->public);
+}
diff --git a/src/libstrongswan/crypto/prfs/fips_prf.h b/src/libstrongswan/crypto/prfs/fips_prf.h
new file mode 100644
index 000000000..283ee1f61
--- /dev/null
+++ b/src/libstrongswan/crypto/prfs/fips_prf.h
@@ -0,0 +1,80 @@
+/**
+ * @file fips_prf.h
+ * 
+ * @brief Interface of fips_prf_t.
+ * 
+ */
+
+/*
+ * Copyright (C) 2006 Martin Willi
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#ifndef FIPS_PRF_H_
+#define FIPS_PRF_H_
+
+typedef struct fips_prf_t fips_prf_t;
+
+#include <library.h>
+#include <crypto/prfs/prf.h>
+#include <crypto/hashers/hasher.h>
+
+/**
+ * @brief Implementation of prf_t using the FIPS 186-2-change1 standard.
+ *
+ * FIPS defines a "General Purpose Random Number Generator" (Revised
+ * Algorithm for Computing m values of x (Appendix 3.1 of FIPS 186-2)). This
+ * implementation is not intended for private key generation and therefore does
+ * not include the "mod q" operation (see FIPS 186-2-change1 p74).
+ * The FIPS PRF is stateful; the key changes every time when bytes are acquired.
+ *
+ * @b Constructors:
+ *  - fips_prf_create()
+ *  - prf_create() using one of the FIPS algorithms
+ * 
+ * @ingroup prfs
+ */
+struct fips_prf_t {
+	
+	/**
+	 * Generic prf_t interface for this fips_prf_t class.
+	 */
+	prf_t prf_interface;
+};
+
+/**
+ * @brief Creates a new fips_prf_t object.
+ * 
+ * FIPS 186-2 defines G() functions used in the PRF function. It can
+ * be implemented either based on SHA1 or DES.
+ *
+ * @param b		size of b (in bytes, not bits)
+ * @param g		G() function to use (e.g. g_sha1)
+ * @return
+ *				- fips_prf_t object
+ *				- NULL if b invalid not supported
+ * 
+ * @ingroup prfs
+ */
+fips_prf_t *fips_prf_create(size_t b, void(*g)(u_int8_t[],chunk_t,u_int8_t[]));
+
+/**
+ * @brief Implementation of the G() function based on SHA1.
+ *
+ * @param t		initialization vector for SHA1 hasher, 20 bytes long
+ * @param c		value to hash, not longer than 512 bit
+ * @param res	result of G(), requries 20 bytes
+ */
+void g_sha1(u_int8_t t[], chunk_t c, u_int8_t res[]);
+
+#endif /* FIPS_PRF_H_ */
diff --git a/src/libstrongswan/crypto/prfs/hmac_prf.c b/src/libstrongswan/crypto/prfs/hmac_prf.c
new file mode 100644
index 000000000..f315f880d
--- /dev/null
+++ b/src/libstrongswan/crypto/prfs/hmac_prf.c
@@ -0,0 +1,118 @@
+/**
+ * @file hmac_prf.c
+ * 
+ * @brief Implementation for hmac_prf_t.
+ * 
+ */
+
+/*
+ * Copyright (C) 2005-2006 Martin Willi
+ * Copyright (C) 2005 Jan Hutter
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "hmac_prf.h"
+
+#include <crypto/hmac.h>
+
+
+typedef struct private_hmac_prf_t private_hmac_prf_t;
+
+/**
+ * Private data of a hma_prf_t object.
+ */
+struct private_hmac_prf_t {
+	/**
+	 * Public hmac_prf_t interface.
+	 */
+	hmac_prf_t public;	
+	
+	/**
+	 * Hmac to use for generation.
+	 */
+	hmac_t *hmac;
+};
+
+/**
+ * Implementation of prf_t.get_bytes.
+ */
+static void get_bytes(private_hmac_prf_t *this, chunk_t seed, u_int8_t *buffer)
+{
+	this->hmac->get_mac(this->hmac, seed, buffer);
+}
+
+/**
+ * Implementation of prf_t.allocate_bytes.
+ */
+static void allocate_bytes(private_hmac_prf_t *this, chunk_t seed, chunk_t *chunk)
+{
+	this->hmac->allocate_mac(this->hmac, seed, chunk);
+}
+
+/**
+ * Implementation of prf_t.get_block_size.
+ */
+static size_t get_block_size(private_hmac_prf_t *this)
+{
+	return this->hmac->get_block_size(this->hmac);
+}
+
+/**
+ * Implementation of prf_t.get_block_size.
+ */
+static size_t get_key_size(private_hmac_prf_t *this)
+{
+	/* for HMAC prfs, IKEv2 uses block size as key size */
+	return this->hmac->get_block_size(this->hmac);
+}
+
+/**
+ * Implementation of prf_t.set_key.
+ */
+static void set_key(private_hmac_prf_t *this, chunk_t key)
+{
+	this->hmac->set_key(this->hmac, key);
+}
+
+/**
+ * Implementation of prf_t.destroy.
+ */
+static void destroy(private_hmac_prf_t *this)
+{
+	this->hmac->destroy(this->hmac);
+	free(this);
+}
+
+/*
+ * Described in header.
+ */
+hmac_prf_t *hmac_prf_create(hash_algorithm_t hash_algorithm)
+{
+	private_hmac_prf_t *this = malloc_thing(private_hmac_prf_t);
+	
+	this->public.prf_interface.get_bytes = (void (*) (prf_t *,chunk_t,u_int8_t*))get_bytes;
+	this->public.prf_interface.allocate_bytes = (void (*) (prf_t*,chunk_t,chunk_t*))allocate_bytes;
+	this->public.prf_interface.get_block_size = (size_t (*) (prf_t*))get_block_size;
+	this->public.prf_interface.get_key_size = (size_t (*) (prf_t*))get_key_size;
+	this->public.prf_interface.set_key = (void (*) (prf_t *,chunk_t))set_key;
+	this->public.prf_interface.destroy = (void (*) (prf_t *))destroy;
+	
+	this->hmac = hmac_create(hash_algorithm);
+	if (this->hmac == NULL)
+	{
+		free(this);
+		return NULL;	
+	}
+	
+	return &(this->public);
+}
diff --git a/src/libstrongswan/crypto/prfs/hmac_prf.h b/src/libstrongswan/crypto/prfs/hmac_prf.h
new file mode 100644
index 000000000..9b06ee3a2
--- /dev/null
+++ b/src/libstrongswan/crypto/prfs/hmac_prf.h
@@ -0,0 +1,65 @@
+/**
+ * @file hmac_prf.h
+ * 
+ * @brief Interface of hmac_prf_t.
+ * 
+ */
+
+/*
+ * Copyright (C) 2005-2006 Martin Willi
+ * Copyright (C) 2005 Jan Hutter
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#ifndef PRF_HMAC_H_
+#define PRF_HMAC_H_
+
+typedef struct hmac_prf_t hmac_prf_t;
+
+#include <library.h>
+#include <crypto/prfs/prf.h>
+#include <crypto/hashers/hasher.h>
+
+/**
+ * @brief Implementation of prf_t interface using the
+ * HMAC algorithm.
+ * 
+ * This simply wraps a hmac_t in a prf_t. More a question of
+ * interface matching.
+ * 
+ * @b Constructors:
+ *  - hmac_prf_create()
+ * 
+ * @ingroup prfs
+ */
+struct hmac_prf_t {
+	
+	/**
+	 * Generic prf_t interface for this hmac_prf_t class.
+	 */
+	prf_t prf_interface;
+};
+
+/**
+ * @brief Creates a new hmac_prf_t object.
+ * 
+ * @param hash_algorithm	hmac's hash algorithm
+ * @return
+ * 							- hmac_prf_t object
+ * 							- NULL if hash not supported
+ * 
+ * @ingroup prfs
+ */
+hmac_prf_t *hmac_prf_create(hash_algorithm_t hash_algorithm);
+
+#endif /*PRF_HMAC_SHA1_H_*/
diff --git a/src/libstrongswan/crypto/prfs/prf.c b/src/libstrongswan/crypto/prfs/prf.c
new file mode 100644
index 000000000..f803829af
--- /dev/null
+++ b/src/libstrongswan/crypto/prfs/prf.c
@@ -0,0 +1,70 @@
+/**
+ * @file prf.c
+ * 
+ * @brief Generic constructor for all prf_t
+ * 
+ */
+
+/*
+ * Copyright (C) 2005-2006 Martin Willi
+ * Copyright (C) 2005 Jan Hutter
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+
+#include "prf.h"
+
+#include <crypto/hashers/hasher.h>
+#include <crypto/prfs/hmac_prf.h>
+#include <crypto/prfs/fips_prf.h>
+
+ENUM_BEGIN(pseudo_random_function_names, PRF_UNDEFINED, PRF_FIPS_DES,
+	"PRF_UNDEFINED",
+	"PRF_FIPS_SHA1_160",
+	"PRF_FIPS_DES");
+ENUM_NEXT(pseudo_random_function_names, PRF_HMAC_MD5, PRF_HMAC_SHA2_512, PRF_FIPS_DES,
+	"PRF_HMAC_MD5",
+	"PRF_HMAC_SHA1",
+	"PRF_HMAC_TIGER",
+	"PRF_AES128_CBC",
+	"PRF_HMAC_SHA2_256",
+	"PRF_HMAC_SHA2_384",
+	"PRF_HMAC_SHA2_512");
+ENUM_END(pseudo_random_function_names, PRF_HMAC_SHA2_512);
+
+/*
+ * Described in header.
+ */
+prf_t *prf_create(pseudo_random_function_t pseudo_random_function)
+{
+	switch (pseudo_random_function)
+	{
+		case PRF_HMAC_SHA1:
+			return (prf_t*)hmac_prf_create(HASH_SHA1);
+		case PRF_HMAC_MD5:
+			return (prf_t*)hmac_prf_create(HASH_MD5);
+		case PRF_HMAC_SHA2_256:
+			return (prf_t*)hmac_prf_create(HASH_SHA256);
+		case PRF_HMAC_SHA2_384:
+			return (prf_t*)hmac_prf_create(HASH_SHA384);
+		case PRF_HMAC_SHA2_512:
+			return (prf_t*)hmac_prf_create(HASH_SHA512);
+		case PRF_FIPS_SHA1_160:
+			return (prf_t*)fips_prf_create(20, g_sha1);
+		case PRF_FIPS_DES:
+		case PRF_HMAC_TIGER:
+		case PRF_AES128_CBC:
+		default:
+			return NULL;
+	}
+}
diff --git a/src/libstrongswan/crypto/prfs/prf.h b/src/libstrongswan/crypto/prfs/prf.h
new file mode 100644
index 000000000..8560a4a9c
--- /dev/null
+++ b/src/libstrongswan/crypto/prfs/prf.h
@@ -0,0 +1,142 @@
+/**
+ * @file prf.h
+ * 
+ * @brief Interface prf_t.
+ * 
+ */
+
+/*
+ * Copyright (C) 2005-2006 Martin Willi
+ * Copyright (C) 2005 Jan Hutter
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#ifndef PRF_H_
+#define PRF_H_
+
+typedef enum pseudo_random_function_t pseudo_random_function_t;
+typedef struct prf_t prf_t;
+
+#include <library.h>
+
+/**
+ * @brief Pseudo random function, as in IKEv2 RFC 3.3.2.
+ *
+ * PRF algorithms not defined in IKEv2 are allocated in "private use"
+ * space.
+ *
+ * @ingroup prfs
+ */
+enum pseudo_random_function_t {
+	PRF_UNDEFINED = 1024,
+	/** Implemented via hmac_prf_t. */
+	PRF_HMAC_MD5 = 1,
+	/** Implemented via hmac_prf_t. */
+	PRF_HMAC_SHA1 = 2,
+	PRF_HMAC_TIGER = 3,
+	PRF_AES128_CBC = 4,
+	/** Implemented via hmac_prf_t. */
+	PRF_HMAC_SHA2_256 = 5,
+	/** Implemented via hmac_prf_t. */
+	PRF_HMAC_SHA2_384 = 6,
+	/** Implemented via hmac_prf_t. */
+	PRF_HMAC_SHA2_512 = 7,
+	/** Implemented via fips_prf_t, other output sizes would be possible */
+	PRF_FIPS_SHA1_160 = 1025,
+	/** Could be implemented via fips_prf_t, uses fixed output size of 160bit */
+	PRF_FIPS_DES = 1026,
+};
+
+/**
+ * enum name for encryption_algorithm_t.
+ */
+extern enum_name_t *pseudo_random_function_names;
+
+/**
+ * @brief Generic interface for pseudo-random-functions.
+ * 
+ * @b Constructors:
+ *  - prf_create()
+ *  - hmac_prf_create()
+ * 
+ * @todo Implement more prf algorithms
+ * 
+ * @ingroup prfs
+ */
+struct prf_t {
+	/**
+	 * @brief Generates pseudo random bytes and writes them in the buffer.
+	 *
+	 * @param this			calling object
+	 * @param seed			a chunk containing the seed for the next bytes
+	 * @param[out] buffer	pointer where the generated bytes will be written
+	 */
+	void (*get_bytes) (prf_t *this, chunk_t seed, u_int8_t *buffer);
+	
+	/**
+	 * @brief Generates pseudo random bytes and allocate space for them.
+	 * 
+	 * @param this			calling object
+	 * @param seed			a chunk containing the seed for the next bytes
+	 * @param[out] chunk	chunk which will hold generated bytes
+	 */
+	void (*allocate_bytes) (prf_t *this, chunk_t seed, chunk_t *chunk);
+	
+	/**
+	 * @brief Get the block size of this prf_t object.
+	 * 
+	 * @param this			calling object
+	 * @return				block size in bytes
+	 */
+	size_t (*get_block_size) (prf_t *this);
+	
+	/**
+	 * @brief Get the key size of this prf_t object.
+	 *
+	 * This is a suggestion only, all implemented PRFs accept variable key
+	 * length.
+	 * 
+	 * @param this			calling object
+	 * @return				key size in bytes
+	 */
+	size_t (*get_key_size) (prf_t *this);
+	
+	/**
+	 * @brief Set the key for this prf_t object.
+	 * 
+	 * @param this			calling object
+	 * @param key			key to set
+	 */
+	void (*set_key) (prf_t *this, chunk_t key);
+	
+	/**
+	 * @brief Destroys a prf object.
+	 *
+	 * @param this 			calling object
+	 */
+	void (*destroy) (prf_t *this);
+};
+
+/**
+ * @brief Generic constructor for a prf_t oject.
+ * 
+ * @param pseudo_random_function	Algorithm to use
+ * @return
+ * 									- prf_t object
+ * 									- NULL if prf algorithm not supported
+ *
+ * @ingroup prfs
+ */
+prf_t *prf_create(pseudo_random_function_t pseudo_random_function);
+
+#endif /*PRF_H_*/