From 4644b0ce3adad5efe574dc125bc3b0cd8f6c2aa7 Mon Sep 17 00:00:00 2001 From: simon Date: Tue, 6 Jul 1999 19:38:54 +0000 Subject: [PATCH] Joris's RSA works; reformat and remove old version git-svn-id: svn://svn.tartarus.org/sgt/putty@173 cda61777-01e9-0310-a592-d414129be87e --- sshrsa.c | 501 +++++++++++++++++++-------------------------------------------- 1 file changed, 149 insertions(+), 352 deletions(-) diff --git a/sshrsa.c b/sshrsa.c index bac360fe..71e1d634 100644 --- a/sshrsa.c +++ b/sshrsa.c @@ -1,16 +1,10 @@ /* * RSA implementation just sufficient for ssh client-side * initialisation step - * Modified by Joris, Jun 1999. + * + * Rewritten for more speed by Joris van Rantwijk, Jun 1999. */ -#define JORIS_RSA - -/*#include -#define RSADEBUG -#define DLVL 2 -#include "stel.h"*/ - #include #include #include @@ -60,386 +54,189 @@ static void freebn(Bignum b) { free(b); } -#ifdef JORIS_RSA - /* - * Compute c = a * b. - * Input is in the first len words of a and b. - * Result is returned in the first 2*len words of c. + * Compute c = a * b. + * Input is in the first len words of a and b. + * Result is returned in the first 2*len words of c. */ static void bigmul(unsigned short *a, unsigned short *b, unsigned short *c, int len) { - int i, j; - unsigned long ai, t; - - for (j = len - 1; j >= 0; j--) - c[j+len] = 0; - - for (i = len - 1; i >= 0; i--) { - ai = a[i]; - t = 0; - for (j = len - 1; j >= 0; j--) { - t += ai * (unsigned long) b[j]; - t += (unsigned long) c[i+j+1]; - c[i+j+1] = t; - t = t >> 16; - } - c[i] = t; - } + int i, j; + unsigned long ai, t; + + for (j = len - 1; j >= 0; j--) + c[j+len] = 0; + + for (i = len - 1; i >= 0; i--) { + ai = a[i]; + t = 0; + for (j = len - 1; j >= 0; j--) { + t += ai * (unsigned long) b[j]; + t += (unsigned long) c[i+j+1]; + c[i+j+1] = (unsigned short)t; + t = t >> 16; + } + c[i] = (unsigned short)t; + } } - /* - * Compute a = a % m. - * Input in first 2*len words of a and first len words of m. - * Output in first 2*len words of a (of which first len words will be zero). - * The MSW of m MUST have its high bit set. + * Compute a = a % m. + * Input in first 2*len words of a and first len words of m. + * Output in first 2*len words of a (of which first len words will be zero). + * The MSW of m MUST have its high bit set. */ static void bigmod(unsigned short *a, unsigned short *m, int len) { - unsigned short m0, m1; - unsigned int h; - int i, k; - - /* Special case for len == 1 */ - if (len == 1) { - a[1] = (((long) a[0] << 16) + a[1]) % m[0]; - a[0] = 0; - return; - } + unsigned short m0, m1; + unsigned int h; + int i, k; + + /* Special case for len == 1 */ + if (len == 1) { + a[1] = (((long) a[0] << 16) + a[1]) % m[0]; + a[0] = 0; + return; + } - m0 = m[0]; - m1 = m[1]; - - for (i = 0; i <= len; i++) { - unsigned long t; - unsigned int q, r, c; - - if (i == 0) { - h = 0; - } else { - h = a[i-1]; - a[i-1] = 0; - } - - /* Find q = h:a[i] / m0 */ - t = ((unsigned long) h << 16) + a[i]; - q = t / m0; - r = t % m0; - - /* Refine our estimate of q by looking at - h:a[i]:a[i+1] / m0:m1 */ - t = (long) m1 * (long) q; - if (t > ((unsigned long) r << 16) + a[i+1]) { - q--; - t -= m1; - r = (r + m0) & 0xffff; /* overflow? */ - if (r >= m0 && t > ((unsigned long) r << 16) + a[i+1]) - q--; - } - - /* Substract q * m from a[i...] */ - c = 0; - for (k = len - 1; k >= 0; k--) { - t = (long) q * (long) m[k]; - t += c; - c = t >> 16; - if ((unsigned short) t > a[i+k]) c++; - a[i+k] -= (unsigned short) t; - } - - /* Add back m in case of borrow */ - if (c != h) { - t = 0; - for (k = len - 1; k >= 0; k--) { - t += m[k]; - t += a[i+k]; - a[i+k] = t; - t = t >> 16; - } - } - } -} + m0 = m[0]; + m1 = m[1]; + for (i = 0; i <= len; i++) { + unsigned long t; + unsigned int q, r, c; -/* - * Compute (base ^ exp) % mod. - * The base MUST be smaller than the modulus. - * The most significant word of mod MUST be non-zero. - * We assume that the result array is the same size as the mod array. - */ -static void modpow(Bignum base, Bignum exp, Bignum mod, Bignum result) -{ - unsigned short *a, *b, *n, *m; - int mshift; - int mlen, i, j; - - /* Allocate m of size mlen, copy mod to m */ - /* We use big endian internally */ - mlen = mod[0]; - m = malloc(mlen * sizeof(unsigned short)); - for (j = 0; j < mlen; j++) m[j] = mod[mod[0] - j]; - - /* Shift m left to make msb bit set */ - for (mshift = 0; mshift < 15; mshift++) - if ((m[0] << mshift) & 0x8000) break; - if (mshift) { - for (i = 0; i < mlen - 1; i++) - m[i] = (m[i] << mshift) | (m[i+1] >> (16-mshift)); - m[mlen-1] = m[mlen-1] << mshift; + if (i == 0) { + h = 0; + } else { + h = a[i-1]; + a[i-1] = 0; } - /* Allocate n of size mlen, copy base to n */ - n = malloc(mlen * sizeof(unsigned short)); - i = mlen - base[0]; - for (j = 0; j < i; j++) n[j] = 0; - for (j = 0; j < base[0]; j++) n[i+j] = base[base[0] - j]; - - /* Allocate a and b of size 2*mlen. Set a = 1 */ - a = malloc(2 * mlen * sizeof(unsigned short)); - b = malloc(2 * mlen * sizeof(unsigned short)); - for (i = 0; i < 2*mlen; i++) a[i] = 0; - a[2*mlen-1] = 1; - - /* Skip leading zero bits of exp. */ - i = 0; j = 15; - while (i < exp[0] && (exp[exp[0] - i] & (1 << j)) == 0) { - j--; - if (j < 0) { i++; j = 15; } + /* Find q = h:a[i] / m0 */ + t = ((unsigned long) h << 16) + a[i]; + q = t / m0; + r = t % m0; + + /* Refine our estimate of q by looking at + h:a[i]:a[i+1] / m0:m1 */ + t = (long) m1 * (long) q; + if (t > ((unsigned long) r << 16) + a[i+1]) { + q--; + t -= m1; + r = (r + m0) & 0xffff; /* overflow? */ + if (r >= m0 && t > ((unsigned long) r << 16) + a[i+1]) + q--; } - /* Main computation */ - while (i < exp[0]) { - while (j >= 0) { - bigmul(a + mlen, a + mlen, b, mlen); - bigmod(b, m, mlen); - if ((exp[exp[0] - i] & (1 << j)) != 0) { - bigmul(b + mlen, n, a, mlen); - bigmod(a, m, mlen); - } else { - unsigned short *t; - t = a; a = b; b = t; - } - j--; - } - i++; j = 15; + /* Substract q * m from a[i...] */ + c = 0; + for (k = len - 1; k >= 0; k--) { + t = (long) q * (long) m[k]; + t += c; + c = t >> 16; + if ((unsigned short) t > a[i+k]) c++; + a[i+k] -= (unsigned short) t; } - /* Fixup result in case the modulus was shifted */ - if (mshift) { - for (i = mlen - 1; i < 2*mlen - 1; i++) - a[i] = (a[i] << mshift) | (a[i+1] >> (16-mshift)); - a[2*mlen-1] = a[2*mlen-1] << mshift; - bigmod(a, m, mlen); - for (i = 2*mlen - 1; i >= mlen; i--) - a[i] = (a[i] >> mshift) | (a[i-1] << (16-mshift)); + /* Add back m in case of borrow */ + if (c != h) { + t = 0; + for (k = len - 1; k >= 0; k--) { + t += m[k]; + t += a[i+k]; + a[i+k] = (unsigned short)t; + t = t >> 16; + } } - - /* Copy result to buffer */ - for (i = 0; i < mlen; i++) - result[result[0] - i] = a[i+mlen]; - - /* Free temporary arrays */ - for (i = 0; i < 2*mlen; i++) a[i] = 0; free(a); - for (i = 0; i < 2*mlen; i++) b[i] = 0; free(b); - for (i = 0; i < mlen; i++) m[i] = 0; free(m); - for (i = 0; i < mlen; i++) n[i] = 0; free(n); -} - -#else - -static int msb(Bignum r) { - int i; - int j; - unsigned short n; - - for (i=r[0]; i>0; i--) - if (r[i]) - break; - - j = (i-1)*16; - n = r[i]; - if (n & 0xFF00) j += 8, n >>= 8; - if (n & 0x00F0) j += 4, n >>= 4; - if (n & 0x000C) j += 2, n >>= 2; - if (n & 0x0002) j += 1, n >>= 1; - - return j; -} - -static void add(Bignum r1, Bignum r2, Bignum result) { - int i; - long stuff = 0; - - enter((">add\n")); - debug(r1); - debug(r2); - - for (i = 1 ;; i++) { - if (i <= r1[0]) - stuff += r1[i]; - if (i <= r2[0]) - stuff += r2[i]; - if (i <= result[0]) - result[i] = stuff & 0xFFFFU; - if (i > r1[0] && i > r2[0] && i >= result[0]) - break; - stuff >>= 16; } - - debug(result); - leave(("sub\n")); - debug(r1); - debug(r2); - - for (i = 1 ;; i++) { - if (i <= r1[0]) - stuff += r1[i]; - if (i <= r2[0]) - stuff -= r2[i]; - if (i <= result[0]) - result[i] = stuff & 0xFFFFU; - if (i > r1[0] && i > r2[0] && i >= result[0]) - break; - stuff = stuff<0 ? -1 : 0; +/* + * Compute (base ^ exp) % mod. + * The base MUST be smaller than the modulus. + * The most significant word of mod MUST be non-zero. + * We assume that the result array is the same size as the mod array. + */ +static void modpow(Bignum base, Bignum exp, Bignum mod, Bignum result) +{ + unsigned short *a, *b, *n, *m; + int mshift; + int mlen, i, j; + + /* Allocate m of size mlen, copy mod to m */ + /* We use big endian internally */ + mlen = mod[0]; + m = malloc(mlen * sizeof(unsigned short)); + for (j = 0; j < mlen; j++) m[j] = mod[mod[0] - j]; + + /* Shift m left to make msb bit set */ + for (mshift = 0; mshift < 15; mshift++) + if ((m[0] << mshift) & 0x8000) break; + if (mshift) { + for (i = 0; i < mlen - 1; i++) + m[i] = (m[i] << mshift) | (m[i+1] >> (16-mshift)); + m[mlen-1] = m[mlen-1] << mshift; } - debug(result); - leave(("ge\n")); - debug(r1); - debug(r2); - - if (r1[0] < r2[0]) - i = r2[0]; - else - i = r1[0]; - - while (i > 0) { - unsigned short n1 = (i > r1[0] ? 0 : r1[i]); - unsigned short n2 = (i > r2[0] ? 0 : r2[i]); - - if (n1 > n2) { - dmsg(("greater\n")); - leave((" r2 */ - } else if (n1 < n2) { - dmsg(("less\n")); - leave(("modmult\n")); - debug(r1); - debug(r2); - debug(modulus); - - for (i=1; i<=result[0]; i++) - result[i] = 0; /* result := 0 */ - for (i=1; i<=temp[0]; i++) - temp[i] = (i > r2[0] ? 0 : r2[i]); /* temp := r2 */ - - bits = 1+msb(r1); - - for (bit = 0; bit < bits; bit++) { - digit = 1 + bit / 16; - smallbit = bit % 16; - - debug(temp); - if (digit <= r1[0] && (r1[digit] & (1<= 0) { + bigmul(a + mlen, a + mlen, b, mlen); + bigmod(b, m, mlen); + if ((exp[exp[0] - i] & (1 << j)) != 0) { + bigmul(b + mlen, n, a, mlen); + bigmod(a, m, mlen); + } else { + unsigned short *t; + t = a; a = b; b = t; + } + j--; } - - add(temp, temp, tmp2); - if (ge(tmp2, modulus)) - sub(tmp2, modulus, temp); - else - add(tmp2, Zero, temp); + i++; j = 15; } - freebn(temp); - freebn(tmp2); - - debug(result); - leave(("modpow\n")); - debug(r1); - debug(r2); - debug(modulus); - - for (i=1; i<=result[0]; i++) - result[i] = (i==1); /* result := 1 */ - for (i=1; i<=temp[0]; i++) - temp[i] = (i > r1[0] ? 0 : r1[i]); /* temp := r1 */ - - bits = 1+msb(r2); - - for (bit = 0; bit < bits; bit++) { - digit = 1 + bit / 16; - smallbit = bit % 16; - - debug(temp); - if (digit <= r2[0] && (r2[digit] & (1<> (16-mshift)); + a[2*mlen-1] = a[2*mlen-1] << mshift; + bigmod(a, m, mlen); + for (i = 2*mlen - 1; i >= mlen; i--) + a[i] = (a[i] >> mshift) | (a[i-1] << (16-mshift)); } - freebn(temp); - freebn(tmp2); + /* Copy result to buffer */ + for (i = 0; i < mlen; i++) + result[result[0] - i] = a[i+mlen]; - debug(result); - leave(("