mirror of
https://git.tartarus.org/simon/putty.git
synced 2025-01-09 17:38:00 +00:00
63b8f537f2
The more features and options I add to PrimeCandidateSource, the more cumbersome it will be to replicate each one in a command-line option to the ultimate primegen() function. So I'm moving to an API in which the client of primegen() constructs a PrimeCandidateSource themself, and passes it in to primegen(). Also, changed the API for pcs_new() so that you don't have to pass 'firstbits' unless you really want to. The net effect is that even though we've added flexibility, we've also simplified the call sites of primegen() in the simple case: if you want a 1234-bit prime, you just need to pass pcs_new(1234) as the argument to primegen, and you're done. The new declaration of primegen() lives in ssh_keygen.h, along with all the types it depends on. So I've had to #include that header in a few new files.
77 lines
3.1 KiB
C
77 lines
3.1 KiB
C
/*
|
|
* sshkeygen.h: routines used internally to key generation.
|
|
*/
|
|
|
|
/* ----------------------------------------------------------------------
|
|
* A table of all the primes that fit in a 16-bit integer. Call
|
|
* init_primes_array to make sure it's been initialised.
|
|
*/
|
|
|
|
#define NSMALLPRIMES 6542 /* number of primes < 65536 */
|
|
extern const unsigned short *const smallprimes;
|
|
void init_smallprimes(void);
|
|
|
|
/* ----------------------------------------------------------------------
|
|
* A system for making up random candidate integers during prime
|
|
* generation. This unconditionally ensures that the numbers have the
|
|
* right number of bits and are not divisible by any prime in the
|
|
* smallprimes[] array above. It can also impose further constraints,
|
|
* as documented below.
|
|
*/
|
|
typedef struct PrimeCandidateSource PrimeCandidateSource;
|
|
|
|
/*
|
|
* pcs_new: you say how many bits you want the prime to have (with the
|
|
* usual semantics that an n-bit number is in the range [2^{n-1},2^n))
|
|
* and also optionally specify what you want its topmost 'nfirst' bits
|
|
* to be.
|
|
*
|
|
* (The 'first' system is used for RSA keys, where you need to arrange
|
|
* that the product of your two primes is in a more tightly
|
|
* constrained range than the factor of 4 you'd get by just generating
|
|
* two (n/2)-bit primes and multiplying them.)
|
|
*/
|
|
PrimeCandidateSource *pcs_new(unsigned bits);
|
|
PrimeCandidateSource *pcs_new_with_firstbits(unsigned bits,
|
|
unsigned first, unsigned nfirst);
|
|
|
|
/* Insist that generated numbers must be congruent to 'res' mod 'mod' */
|
|
void pcs_require_residue(PrimeCandidateSource *s, mp_int *mod, mp_int *res);
|
|
|
|
/* Convenience wrapper for the common case where res = 1 */
|
|
void pcs_require_residue_1(PrimeCandidateSource *s, mp_int *mod);
|
|
|
|
/* Insist that generated numbers must _not_ be congruent to 'res' mod
|
|
* 'mod'. This is used to avoid being 1 mod the RSA public exponent,
|
|
* which is small, so it only needs ordinary integer parameters. */
|
|
void pcs_avoid_residue_small(PrimeCandidateSource *s,
|
|
unsigned mod, unsigned res);
|
|
|
|
/* Prepare a PrimeCandidateSource to actually generate numbers. This
|
|
* function does last-minute computation that has to be delayed until
|
|
* all constraints have been input. */
|
|
void pcs_ready(PrimeCandidateSource *s);
|
|
|
|
/* Actually generate a candidate integer. You must free the result, of
|
|
* course. */
|
|
mp_int *pcs_generate(PrimeCandidateSource *s);
|
|
|
|
/* Free a PrimeCandidateSource. */
|
|
void pcs_free(PrimeCandidateSource *s);
|
|
|
|
/* Return some internal fields of the PCS. Used by testcrypt for
|
|
* unit-testing this system. */
|
|
void pcs_inspect(PrimeCandidateSource *pcs, mp_int **limit_out,
|
|
mp_int **factor_out, mp_int **addend_out);
|
|
|
|
/* Query functions for primegen to use */
|
|
unsigned pcs_get_bits(PrimeCandidateSource *pcs);
|
|
|
|
/* ----------------------------------------------------------------------
|
|
* The top-level API for generating primes.
|
|
*/
|
|
|
|
/* This function consumes and frees the PrimeCandidateSource you give it */
|
|
mp_int *primegen(PrimeCandidateSource *pcs,
|
|
int phase, progfn_t pfn, void *pfnparam);
|