зеркало из https://github.com/github/putty.git
231 строка
6.8 KiB
C
231 строка
6.8 KiB
C
/*
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* Diffie-Hellman implementation for PuTTY.
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*/
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#include "ssh.h"
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/*
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* The primes used in the group1 and group14 key exchange.
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*/
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static const unsigned char P1[] = {
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0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
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0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
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0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
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0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
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0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
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0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
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0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
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0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
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0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
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0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE6, 0x53, 0x81,
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0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
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};
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static const unsigned char P14[] = {
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0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
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0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
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0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
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0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
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0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
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0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
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0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
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0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
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0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
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0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE4, 0x5B, 0x3D,
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0xC2, 0x00, 0x7C, 0xB8, 0xA1, 0x63, 0xBF, 0x05, 0x98, 0xDA, 0x48, 0x36,
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0x1C, 0x55, 0xD3, 0x9A, 0x69, 0x16, 0x3F, 0xA8, 0xFD, 0x24, 0xCF, 0x5F,
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0x83, 0x65, 0x5D, 0x23, 0xDC, 0xA3, 0xAD, 0x96, 0x1C, 0x62, 0xF3, 0x56,
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0x20, 0x85, 0x52, 0xBB, 0x9E, 0xD5, 0x29, 0x07, 0x70, 0x96, 0x96, 0x6D,
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0x67, 0x0C, 0x35, 0x4E, 0x4A, 0xBC, 0x98, 0x04, 0xF1, 0x74, 0x6C, 0x08,
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0xCA, 0x18, 0x21, 0x7C, 0x32, 0x90, 0x5E, 0x46, 0x2E, 0x36, 0xCE, 0x3B,
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0xE3, 0x9E, 0x77, 0x2C, 0x18, 0x0E, 0x86, 0x03, 0x9B, 0x27, 0x83, 0xA2,
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0xEC, 0x07, 0xA2, 0x8F, 0xB5, 0xC5, 0x5D, 0xF0, 0x6F, 0x4C, 0x52, 0xC9,
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0xDE, 0x2B, 0xCB, 0xF6, 0x95, 0x58, 0x17, 0x18, 0x39, 0x95, 0x49, 0x7C,
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0xEA, 0x95, 0x6A, 0xE5, 0x15, 0xD2, 0x26, 0x18, 0x98, 0xFA, 0x05, 0x10,
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0x15, 0x72, 0x8E, 0x5A, 0x8A, 0xAC, 0xAA, 0x68, 0xFF, 0xFF, 0xFF, 0xFF,
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0xFF, 0xFF, 0xFF, 0xFF
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};
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/*
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* The generator g = 2 (used for both group1 and group14).
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*/
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static const unsigned char G[] = { 2 };
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static const struct ssh_kex ssh_diffiehellman_group1_sha1 = {
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"diffie-hellman-group1-sha1", "group1",
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KEXTYPE_DH, P1, G, lenof(P1), lenof(G), &ssh_sha1
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};
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static const struct ssh_kex *const group1_list[] = {
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&ssh_diffiehellman_group1_sha1
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};
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const struct ssh_kexes ssh_diffiehellman_group1 = {
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sizeof(group1_list) / sizeof(*group1_list),
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group1_list
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};
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static const struct ssh_kex ssh_diffiehellman_group14_sha1 = {
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"diffie-hellman-group14-sha1", "group14",
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KEXTYPE_DH, P14, G, lenof(P14), lenof(G), &ssh_sha1
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};
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static const struct ssh_kex *const group14_list[] = {
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&ssh_diffiehellman_group14_sha1
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};
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const struct ssh_kexes ssh_diffiehellman_group14 = {
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sizeof(group14_list) / sizeof(*group14_list),
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group14_list
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};
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static const struct ssh_kex ssh_diffiehellman_gex_sha256 = {
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"diffie-hellman-group-exchange-sha256", NULL,
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KEXTYPE_DH, NULL, NULL, 0, 0, &ssh_sha256
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};
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static const struct ssh_kex ssh_diffiehellman_gex_sha1 = {
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"diffie-hellman-group-exchange-sha1", NULL,
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KEXTYPE_DH, NULL, NULL, 0, 0, &ssh_sha1
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};
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static const struct ssh_kex *const gex_list[] = {
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&ssh_diffiehellman_gex_sha256,
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&ssh_diffiehellman_gex_sha1
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};
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const struct ssh_kexes ssh_diffiehellman_gex = {
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sizeof(gex_list) / sizeof(*gex_list),
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gex_list
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};
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/*
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* Variables.
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*/
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struct dh_ctx {
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Bignum x, e, p, q, qmask, g;
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};
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/*
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* Common DH initialisation.
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*/
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static void dh_init(struct dh_ctx *ctx)
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{
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ctx->q = bignum_rshift(ctx->p, 1);
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ctx->qmask = bignum_bitmask(ctx->q);
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ctx->x = ctx->e = NULL;
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}
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/*
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* Initialise DH for a standard group.
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*/
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void *dh_setup_group(const struct ssh_kex *kex)
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{
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struct dh_ctx *ctx = snew(struct dh_ctx);
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ctx->p = bignum_from_bytes(kex->pdata, kex->plen);
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ctx->g = bignum_from_bytes(kex->gdata, kex->glen);
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dh_init(ctx);
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return ctx;
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}
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/*
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* Initialise DH for a server-supplied group.
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*/
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void *dh_setup_gex(Bignum pval, Bignum gval)
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{
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struct dh_ctx *ctx = snew(struct dh_ctx);
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ctx->p = copybn(pval);
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ctx->g = copybn(gval);
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dh_init(ctx);
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return ctx;
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}
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/*
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* Clean up and free a context.
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*/
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void dh_cleanup(void *handle)
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{
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struct dh_ctx *ctx = (struct dh_ctx *)handle;
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freebn(ctx->x);
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freebn(ctx->e);
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freebn(ctx->p);
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freebn(ctx->g);
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freebn(ctx->q);
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freebn(ctx->qmask);
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sfree(ctx);
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}
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/*
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* DH stage 1: invent a number x between 1 and q, and compute e =
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* g^x mod p. Return e.
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*
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* If `nbits' is greater than zero, it is used as an upper limit
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* for the number of bits in x. This is safe provided that (a) you
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* use twice as many bits in x as the number of bits you expect to
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* use in your session key, and (b) the DH group is a safe prime
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* (which SSH demands that it must be).
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*
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* P. C. van Oorschot, M. J. Wiener
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* "On Diffie-Hellman Key Agreement with Short Exponents".
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* Advances in Cryptology: Proceedings of Eurocrypt '96
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* Springer-Verlag, May 1996.
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*/
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Bignum dh_create_e(void *handle, int nbits)
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{
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struct dh_ctx *ctx = (struct dh_ctx *)handle;
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int i;
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int nbytes;
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unsigned char *buf;
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nbytes = ssh1_bignum_length(ctx->qmask);
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buf = snewn(nbytes, unsigned char);
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do {
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/*
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* Create a potential x, by ANDing a string of random bytes
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* with qmask.
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*/
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if (ctx->x)
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freebn(ctx->x);
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if (nbits == 0 || nbits > bignum_bitcount(ctx->qmask)) {
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ssh1_write_bignum(buf, ctx->qmask);
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for (i = 2; i < nbytes; i++)
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buf[i] &= random_byte();
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ssh1_read_bignum(buf, nbytes, &ctx->x); /* can't fail */
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} else {
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int b, nb;
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ctx->x = bn_power_2(nbits);
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b = nb = 0;
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for (i = 0; i < nbits; i++) {
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if (nb == 0) {
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nb = 8;
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b = random_byte();
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}
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bignum_set_bit(ctx->x, i, b & 1);
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b >>= 1;
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nb--;
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}
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}
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} while (bignum_cmp(ctx->x, One) <= 0 || bignum_cmp(ctx->x, ctx->q) >= 0);
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sfree(buf);
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/*
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* Done. Now compute e = g^x mod p.
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*/
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ctx->e = modpow(ctx->g, ctx->x, ctx->p);
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return ctx->e;
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}
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/*
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* DH stage 2: given a number f, compute K = f^x mod p.
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*/
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Bignum dh_find_K(void *handle, Bignum f)
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{
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struct dh_ctx *ctx = (struct dh_ctx *)handle;
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Bignum ret;
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ret = modpow(f, ctx->x, ctx->p);
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return ret;
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}
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