/*
- silcSilcRng.h
+ silcrng.h
- Author: Pekka Riikonen <priikone@poseidon.pspt.fi>
+ Author: Pekka Riikonen <priikone@silcnet.org>
- Copyright (C) 1997 - 2001 Pekka Riikonen
+ Copyright (C) 1997 - 2002 Pekka Riikonen
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.
-
+ the Free Software Foundation; version 2 of the License.
+
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.
*/
-/*
-SILC Random Number Generator is cryptographically strong pseudo random
-generator. It is used to generate all the random numbers needed in the
-SILC sessions. All key material and other sources needing random numbers
-use this generator.
-
-The RNG has a random pool of 1024 bytes of size that provides the actual
-random numbers for the application. The pool is initialized when the
-RNG is allocated and initialized with silc_rng_alloc and silc_rng_init
-functions, respectively.
-
-
-Random Pool Initializing
-
-The RNG's random pool is the source of all random output data. The pool is
-initialized with silc_rng_init and application can reseed it at any time
-calling the silc_rng_add_noise function.
-
-The initializing phase attempts to set the random pool in a state that it
-is impossible to learn the input data to the RNG all any random output
-data. This is achieved by acquiring noise from various system sources. The
-first source is is called to provide "soft noise". This noise is various
-data from system's processes. The second source is called to provide
-"medium noise". This noise is various output data from executed commands.
-Usually the commands are Unix `ps' and `ls' commands with various options.
-The last source is called to provide "hard noise" and is noise from
-system's /dev/random, if it exists.
-
-
-Stirring the Random Pool
-
-Every time data is acquired from any source, the pool is stirred. The
-stirring process performs an CFB (cipher feedback) encryption with SHA1
-algorithm to the entire random pool. First it acquires an IV (Initial
-Vector) from the constant location of the pool and performs the first CFB
-pass. Then it acquires a new encryption key from variable location of the
-pool and performs the second CFB pass. The encryption key thus is always
-acquired from unguessable data.
-
-The encryption process to the entire random pool assures that it is
-impossible to learn the input data to the random pool without breaking the
-encryption process. This would effectively mean breaking the SHA1 hash
-function. The encryption process also assures that each random output from
-the random pool is secured with cryptographically strong function, the
-SHA1 in this case.
-
-The random pool can be restirred by the application at any point by
-calling the silc_rng_add_noise function. This function adds new noise to
-the pool and then stirs the entire pool.
-
-
-Stirring Threshholds
-
-The random pool has two threshholds that controls when the random pool
-needs more new noise and requires restirring. As previously mentioned, the
-application may do this by calling the silc_rng_add_noise. However, the
-RNG performs this also automatically.
-
-The first threshhold gets soft noise from system and stirs the random pool.
-The threshhold is reached after 64 bits of random data has been fetched
-from the RNG. After the 64 bits, the soft noise acquiring and restirring
-process is performed every 8 bits of random output data until the second
-threshhold is reached.
-
-The second threshhold gets hard noise from system and stirs the random
-pool. The threshhold is reached after 160 bits of random output. After the
-noise is acquired (from /dev/random) the random pool is stirred and the
-threshholds are set to zero. The process is repeated again after 64 bits of
-output for first threshhold and after 160 bits of output for the second
-threshhold.
-
-
-Internal State of the Random Pool
-
-The random pool has also internal state that provides several variable
-distinct points to the random pool where the data is fetched. The state
-changes every 8 bits of output data and it is guaranteed that the fetched
-8 bits of data is from distinct location compared to the previous 8 bits.
-It is also guaranteed that the internal state never wraps before
-restirring the entire random pool. The internal state means that the data
-is not fetched linearly from the pool, eg. starting from zero and wrapping
-at the end of the pool. The internal state is not dependent of any random
-data in the pool. The internal states are initialized (by default the pool
-is splitted to four different sections (states)) at the RNG
-initialization phase. The state's current position is added linearly and
-wraps at the the start of the next state. The states provides the distinct
-locations.
-
-
-Security Implications
-
-The security of this random number generator, like of any other RNG's,
-depends of the initial state of the RNG. The initial state of the random
-number generators must be unknown to an adversary. This means that after
-the RNG is initialized it is required that the input data to the RNG and
-the output data to the application has no correlation of any kind that
-could be used to compromise the acquired random numbers or any future
-random numbers.
-
-It is, however, clear that the correlation exists but it needs to be
-hard to solve for an adversary. To accomplish this the input data to the
-random number generator needs to be secret. Usually this is impossible to
-achieve. That is why SILC's RNG acquires the noise from three different
-sources and provides for the application an interface to add more noise at
-any time. The first source is known to the adversary but requires exact
-timing to get all of the input data. However, getting only partial data
-is easy. The second source depends on the place of execution of the
-application. Getting at least partial data is easy but securing for
-example the user's home directory from outside access makes it harder. The
-last source, the /dev/random is considered to be the most secure source of
-data. An adversary is not considered to have any access on this data. This
-of course greatly depends on the operating system.
-
-These three sources are considered to be adequate since the random pool is
-relatively large and the output of each bit of the random pool is secured
-by cryptographically secure function, the SHA1 in CFB mode encryption.
-Furthermore the application may provide other random data, such as random
-key strokes or mouse movement to the RNG. However, it is recommended that
-the application would not be the single point of source for the RNG, in
-either intializing or reseeding phases later in the session. Good solution
-is probably to use both, the application's seeds and the RNG's own
-sources, equally.
-
-The RNG must also assure that any old or future random numbers are not
-compromised if an adversary would learn the initial input data (or any
-input data for that matter). The SILC's RNG provides good protection for
-this even if the some of the output bits would be compromised in old or
-future random numbers. The RNG reinitalizes (reseeds) itself using the
-threshholds after every 64 and 160 bits of output. This is considered to be
-adequate even if some of the bits would get compromised. Also, the
-applications that use the RNG usually fetches at least 256 bits from the
-RNG. This means that everytime RNG is accessed both of the threshholds are
-reached. This should mean that the RNG is never too long in an compromised
-state and recovers as fast as possible.
-
-Currently the SILC's RNG does not use random seed files to store some
-random data for future initializing. This is important and must be
-implemented in the future.
-*/
+/****h* silccrypt/SilcRNGAPI
+ *
+ * DESCRIPTION
+ *
+ * SILC Random Number Generator is cryptographically strong pseudo random
+ * number generator. It is used to generate all the random numbers needed
+ * in the SILC sessions. All key material and other sources needing random
+ * numbers use this generator.
+ *
+ * The interface provides functions for retrieving different size of
+ * random number and arbitrary length of random data buffers. The interface
+ * also defines Global RNG API which makes it possible to call any
+ * RNG API function without specific RNG context.
+ *
+ ***/
#ifndef SILCRNG_H
#define SILCRNG_H
-/* Forward declaration. Actual object is in source file. */
-typedef struct SilcRngObjectStruct *SilcRng;
+/****s* silccrypt/SilcRNGAPI/SilcRng
+ *
+ * NAME
+ *
+ * typedef struct SilcRngStruct *SilcRng;
+ *
+ * DESCRIPTION
+ *
+ * This context is the actual Random Number Generator and is allocated
+ * by silc_rng_alloc and given as argument usually to all silc_rng_*
+ * functions. It is freed by the silc_rng_free function. The RNG is
+ * initialized by calling the silc_rng_init function.
+ *
+ ***/
+typedef struct SilcRngStruct *SilcRng;
/* Prototypes */
-SilcRng silc_rng_alloc();
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_alloc
+ *
+ * SYNOPSIS
+ *
+ * SilcRng silc_rng_alloc(void);
+ *
+ * DESCRIPTION
+ *
+ * Allocates new SILC random number generator and returns context to
+ * it. After the RNG is allocated it must be initialized by calling
+ * silc_rng_init before it actually can be used to produce any random
+ * number. This function returns NULL if RNG could not allocated.
+ *
+ ***/
+SilcRng silc_rng_alloc(void);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_free
+ *
+ * SYNOPSIS
+ *
+ * void silc_rng_free(SilcRng rng);
+ *
+ * DESCRIPTION
+ *
+ * Frees the random number generator and destroys the random number
+ * pool.
+ *
+ ***/
void silc_rng_free(SilcRng rng);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_init
+ *
+ * SYNOPSIS
+ *
+ * void silc_rng_init(SilcRng rng);
+ *
+ * DESCRIPTION
+ *
+ * This function is used to initialize the random number generator.
+ * This is the function that must be called after the RNG is allocated
+ * by calling silc_rng_alloc. RNG cannot be used before this function
+ * is called.
+ *
+ * NOTES
+ *
+ * This function may be slow since it will acquire secret noise from
+ * the environment in an attempt to set the RNG in unguessable state.
+ *
+ ***/
void silc_rng_init(SilcRng rng);
-unsigned char silc_rng_get_byte(SilcRng rng);
-uint16 silc_rng_get_rn16(SilcRng rng);
-uint32 silc_rng_get_rn32(SilcRng rng);
-unsigned char *silc_rng_get_rn_string(SilcRng rng, uint32 len);
-unsigned char *silc_rng_get_rn_data(SilcRng rng, uint32 len);
-void silc_rng_add_noise(SilcRng rng, unsigned char *buffer, uint32 len);
-
-int silc_rng_global_init(SilcRng rng);
-int silc_rng_global_uninit();
-unsigned char silc_rng_global_get_byte();
-uint16 silc_rng_global_get_rn16();
-uint32 silc_rng_global_get_rn32();
-unsigned char *silc_rng_global_get_rn_string(uint32 len);
-unsigned char *silc_rng_global_get_rn_data(uint32 len);
-void silc_rng_global_add_noise(unsigned char *buffer, uint32 len);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_get_byte
+ *
+ * SYNOPSIS
+ *
+ * SilcUInt8 silc_rng_get_byte(SilcRng rng);
+ *
+ * DESCRIPTION
+ *
+ * Returns one 8-bit random byte from the random number generator.
+ *
+ ***/
+SilcUInt8 silc_rng_get_byte(SilcRng rng);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_get_rn16
+ *
+ * SYNOPSIS
+ *
+ * SilcUInt16 silc_rng_get_rn16(SilcRng rng);
+ *
+ * DESCRIPTION
+ *
+ * Returns one 16-bit random number from the random number generator.
+ *
+ ***/
+SilcUInt16 silc_rng_get_rn16(SilcRng rng);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_get_rn32
+ *
+ * SYNOPSIS
+ *
+ * SilcUInt32 silc_rng_get_rn32(SilcRng rng);
+ *
+ * DESCRIPTION
+ *
+ * Returns one 32-bit random number from the random number generator.
+ *
+ ***/
+SilcUInt32 silc_rng_get_rn32(SilcRng rng);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_get_rn_string
+ *
+ * SYNOPSIS
+ *
+ * unsigned char *silc_rng_get_rn_string(SilcRng rng, SilcUInt32 len);
+ *
+ * DESCRIPTION
+ *
+ * Returns random string in HEX form of the length of `len' bytes.
+ * The caller must free returned data buffer.
+ *
+ ***/
+unsigned char *silc_rng_get_rn_string(SilcRng rng, SilcUInt32 len);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_get_rn_data
+ *
+ * SYNOPSIS
+ *
+ * unsigned char *silc_rng_get_rn_data(SilcRng rng, SilcUInt32 len);
+ *
+ * DESCRIPTION
+ *
+ * Returns random binary data of the length of `len' bytes. The
+ * caller must free returned data buffer.
+ *
+ ***/
+unsigned char *silc_rng_get_rn_data(SilcRng rng, SilcUInt32 len);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_add_noise
+ *
+ * SYNOPSIS
+ *
+ * void silc_rng_add_noise(SilcRng rng, unsigned char *buffer, SilcUInt32 len);
+ *
+ * DESCRIPTION
+ *
+ * Add the data buffer indicated by `buffer' of length of `len' bytes
+ * as noise to the random number generator. The random number generator
+ * is restirred (reseeded) when this function is called.
+ *
+ ***/
+void silc_rng_add_noise(SilcRng rng, unsigned char *buffer, SilcUInt32 len);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_global_init
+ *
+ * SYNOPSIS
+ *
+ * bool silc_rng_global_init(SilcRng rng);
+ *
+ * DESCRIPTION
+ *
+ * This function sets the `rng' if non-NULL as global RNG context.
+ * When any of the silc_rng_global_* functions is called the `rng' is
+ * used as RNG. If `rng' is NULL this will allocate new RNG as global
+ * RNG. The application in this case must free it later by calling
+ * silc_rng_global_uninit. Returns TRUE after Global RNG is initialized.
+ *
+ * NOTES
+ *
+ * If `rng' was non-NULL, the silc_rng_init must have been called for
+ * the `rng' already.
+ *
+ * This function can be used to define the `rng' as global RNG and then
+ * use silc_rng_global_* functions easily without need to provide
+ * the RNG as argument.
+ *
+ ***/
+bool silc_rng_global_init(SilcRng rng);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_global_uninit
+ *
+ * SYNOPSIS
+ *
+ * bool silc_rng_global_uninit(void);
+ *
+ * DESCRIPTION
+ *
+ * Uninitialized the Global RNG object and frees it. This should not
+ * be called if silc_rng_global_init was called with non-NULL RNG.
+ *
+ ***/
+bool silc_rng_global_uninit(void);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_global_get_byte
+ *
+ * SYNOPSIS
+ *
+ * SilcUInt8 silc_rng_global_get_byte(void);
+ *
+ * DESCRIPTION
+ *
+ * Returns one 8-bit random byte from the random number generator.
+ *
+ ***/
+SilcUInt8 silc_rng_global_get_byte(void);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_global_get_byte_fast
+ *
+ * SYNOPSIS
+ *
+ * SilcUInt8 silc_rng_global_get_byte_fast(void);
+ *
+ * DESCRIPTION
+ *
+ * Returns one 8-bit random byte from the random number generator as
+ * fast as possible.
+ *
+ * NOTES
+ *
+ * This will read the data from /dev/urandom if it is available in the
+ * operating system, since this may be faster than retrieving a byte
+ * from the SILC RNG. If /dev/urandom is not available this will take
+ * the byte from SILC RNG and is effectively same as silc_rng_get_byte.
+ *
+ ***/
+SilcUInt8 silc_rng_global_get_byte_fast(void);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_global_get_rn16
+ *
+ * SYNOPSIS
+ *
+ * SilcUInt16 silc_rng_global_get_rn16(void);
+ *
+ * DESCRIPTION
+ *
+ * Returns one 16-bit random number from the random number generator.
+ *
+ ***/
+SilcUInt16 silc_rng_global_get_rn16(void);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_global_get_rn32
+ *
+ * SYNOPSIS
+ *
+ * SilcUInt32 silc_rng_global_get_rn32(void);
+ *
+ * DESCRIPTION
+ *
+ * Returns one 32-bit random number from the random number generator.
+ *
+ ***/
+SilcUInt32 silc_rng_global_get_rn32(void);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_global_get_rn_string
+ *
+ * SYNOPSIS
+ *
+ * unsigned char *silc_rng_global_get_rn_string(SilcUInt32 len);
+ *
+ * DESCRIPTION
+ *
+ * Returns random string in HEX form of the length of `len' bytes.
+ * The caller must free returned data buffer.
+ *
+ ***/
+unsigned char *silc_rng_global_get_rn_string(SilcUInt32 len);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_global_get_rn_data
+ *
+ * SYNOPSIS
+ *
+ * unsigned char *silc_rng_global_get_rn_data(SilcUInt32 len);
+ *
+ * DESCRIPTION
+ *
+ * Returns random binary data of the length of `len' bytes. The
+ * caller must free returned data buffer.
+ *
+ ***/
+unsigned char *silc_rng_global_get_rn_data(SilcUInt32 len);
+
+/****f* silccrypt/SilcRNGAPI/silc_rng_global_add_noise
+ *
+ * SYNOPSIS
+ *
+ * void silc_rng_global_add_noise(unsigned char *buffer, SilcUInt32 len);
+ *
+ * DESCRIPTION
+ *
+ * Add the data buffer indicated by `buffer' of length of `len' bytes
+ * as noise to the random number generator. The random number generator
+ * is restirred (reseeded) when this function is called.
+ *
+ ***/
+
+void silc_rng_global_add_noise(unsigned char *buffer, SilcUInt32 len);
#endif
projects / silc.git / blobdiff