X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/6e522441172d5b1c2a2fa4d0f6bbe905ce6b647a..bace54316e12bf47756c5c53cd97baf533d95db5:/sshbn.c diff --git a/sshbn.c b/sshbn.c index 693b4ac7..6615d41d 100644 --- a/sshbn.c +++ b/sshbn.c @@ -11,10 +11,24 @@ unsigned short bnZero[1] = { 0 }; unsigned short bnOne[2] = { 1, 1 }; +/* + * The Bignum format is an array of `unsigned short'. The first + * element of the array counts the remaining elements. The + * remaining elements express the actual number, base 2^16, _least_ + * significant digit first. (So it's trivial to extract the bit + * with value 2^n for any n.) + * + * All Bignums in this module are positive. Negative numbers must + * be dealt with outside it. + * + * INVARIANT: the most significant word of any Bignum must be + * nonzero. + */ + Bignum Zero = bnZero, One = bnOne; Bignum newbn(int length) { - Bignum b = malloc((length+1)*sizeof(unsigned short)); + Bignum b = smalloc((length+1)*sizeof(unsigned short)); if (!b) abort(); /* FIXME */ memset(b, 0, (length+1)*sizeof(*b)); @@ -23,7 +37,7 @@ Bignum newbn(int length) { } Bignum copybn(Bignum orig) { - Bignum b = malloc((orig[0]+1)*sizeof(unsigned short)); + Bignum b = smalloc((orig[0]+1)*sizeof(unsigned short)); if (!b) abort(); /* FIXME */ memcpy(b, orig, (orig[0]+1)*sizeof(*b)); @@ -35,7 +49,7 @@ void freebn(Bignum b) { * Burn the evidence, just in case. */ memset(b, 0, sizeof(b[0]) * (b[0] + 1)); - free(b); + sfree(b); } /* @@ -170,16 +184,17 @@ static void internal_mod(unsigned short *a, int alen, * The most significant word of mod MUST be non-zero. * We assume that the result array is the same size as the mod array. */ -void modpow(Bignum base, Bignum exp, Bignum mod, Bignum result) +Bignum modpow(Bignum base, Bignum exp, Bignum mod) { unsigned short *a, *b, *n, *m; int mshift; int mlen, i, j; + Bignum result; /* Allocate m of size mlen, copy mod to m */ /* We use big endian internally */ mlen = mod[0]; - m = malloc(mlen * sizeof(unsigned short)); + m = smalloc(mlen * sizeof(unsigned short)); for (j = 0; j < mlen; j++) m[j] = mod[mod[0] - j]; /* Shift m left to make msb bit set */ @@ -192,14 +207,14 @@ void modpow(Bignum base, Bignum exp, Bignum mod, Bignum result) } /* Allocate n of size mlen, copy base to n */ - n = malloc(mlen * sizeof(unsigned short)); + n = smalloc(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)); + a = smalloc(2 * mlen * sizeof(unsigned short)); + b = smalloc(2 * mlen * sizeof(unsigned short)); for (i = 0; i < 2*mlen; i++) a[i] = 0; a[2*mlen-1] = 1; @@ -238,14 +253,18 @@ void modpow(Bignum base, Bignum exp, Bignum mod, Bignum result) } /* Copy result to buffer */ + result = newbn(mod[0]); for (i = 0; i < mlen; i++) result[result[0] - i] = a[i+mlen]; + while (result[0] > 1 && result[result[0]] == 0) result[0]--; /* 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); + for (i = 0; i < 2*mlen; i++) a[i] = 0; sfree(a); + for (i = 0; i < 2*mlen; i++) b[i] = 0; sfree(b); + for (i = 0; i < mlen; i++) m[i] = 0; sfree(m); + for (i = 0; i < mlen; i++) n[i] = 0; sfree(n); + + return result; } /* @@ -253,16 +272,17 @@ void modpow(Bignum base, Bignum exp, Bignum mod, Bignum result) * The most significant word of mod MUST be non-zero. * We assume that the result array is the same size as the mod array. */ -void modmul(Bignum p, Bignum q, Bignum mod, Bignum result) +Bignum modmul(Bignum p, Bignum q, Bignum mod) { unsigned short *a, *n, *m, *o; int mshift; int pqlen, mlen, i, j; + Bignum result; /* Allocate m of size mlen, copy mod to m */ /* We use big endian internally */ mlen = mod[0]; - m = malloc(mlen * sizeof(unsigned short)); + m = smalloc(mlen * sizeof(unsigned short)); for (j = 0; j < mlen; j++) m[j] = mod[mod[0] - j]; /* Shift m left to make msb bit set */ @@ -277,19 +297,19 @@ void modmul(Bignum p, Bignum q, Bignum mod, Bignum result) pqlen = (p[0] > q[0] ? p[0] : q[0]); /* Allocate n of size pqlen, copy p to n */ - n = malloc(pqlen * sizeof(unsigned short)); + n = smalloc(pqlen * sizeof(unsigned short)); i = pqlen - p[0]; for (j = 0; j < i; j++) n[j] = 0; for (j = 0; j < p[0]; j++) n[i+j] = p[p[0] - j]; /* Allocate o of size pqlen, copy q to o */ - o = malloc(pqlen * sizeof(unsigned short)); + o = smalloc(pqlen * sizeof(unsigned short)); i = pqlen - q[0]; for (j = 0; j < i; j++) o[j] = 0; for (j = 0; j < q[0]; j++) o[i+j] = q[q[0] - j]; /* Allocate a of size 2*pqlen for result */ - a = malloc(2 * pqlen * sizeof(unsigned short)); + a = smalloc(2 * pqlen * sizeof(unsigned short)); /* Main computation */ internal_mul(n, o, a, pqlen); @@ -306,14 +326,18 @@ void modmul(Bignum p, Bignum q, Bignum mod, Bignum result) } /* Copy result to buffer */ + result = newbn(mod[0]); for (i = 0; i < mlen; i++) result[result[0] - i] = a[i+2*pqlen-mlen]; + while (result[0] > 1 && result[result[0]] == 0) result[0]--; /* Free temporary arrays */ - for (i = 0; i < 2*pqlen; i++) a[i] = 0; free(a); - for (i = 0; i < mlen; i++) m[i] = 0; free(m); - for (i = 0; i < pqlen; i++) n[i] = 0; free(n); - for (i = 0; i < pqlen; i++) o[i] = 0; free(o); + for (i = 0; i < 2*pqlen; i++) a[i] = 0; sfree(a); + for (i = 0; i < mlen; i++) m[i] = 0; sfree(m); + for (i = 0; i < pqlen; i++) n[i] = 0; sfree(n); + for (i = 0; i < pqlen; i++) o[i] = 0; sfree(o); + + return result; } /* @@ -331,7 +355,7 @@ void bigmod(Bignum p, Bignum mod, Bignum result, Bignum quotient) /* Allocate m of size mlen, copy mod to m */ /* We use big endian internally */ mlen = mod[0]; - m = malloc(mlen * sizeof(unsigned short)); + m = smalloc(mlen * sizeof(unsigned short)); for (j = 0; j < mlen; j++) m[j] = mod[mod[0] - j]; /* Shift m left to make msb bit set */ @@ -348,7 +372,7 @@ void bigmod(Bignum p, Bignum mod, Bignum result, Bignum quotient) if (plen <= mlen) plen = mlen+1; /* Allocate n of size plen, copy p to n */ - n = malloc(plen * sizeof(unsigned short)); + n = smalloc(plen * sizeof(unsigned short)); for (j = 0; j < plen; j++) n[j] = 0; for (j = 1; j <= p[0]; j++) n[plen-j] = p[j]; @@ -372,8 +396,8 @@ void bigmod(Bignum p, Bignum mod, Bignum result, Bignum quotient) } /* Free temporary arrays */ - for (i = 0; i < mlen; i++) m[i] = 0; free(m); - for (i = 0; i < plen; i++) n[i] = 0; free(n); + for (i = 0; i < mlen; i++) m[i] = 0; sfree(m); + for (i = 0; i < plen; i++) n[i] = 0; sfree(n); } /* @@ -550,7 +574,7 @@ Bignum bigmuladd(Bignum a, Bignum b, Bignum addend) { Bignum ret; /* mlen space for a, mlen space for b, 2*mlen for result */ - workspace = malloc(mlen * 4 * sizeof(unsigned short)); + workspace = smalloc(mlen * 4 * sizeof(unsigned short)); for (i = 0; i < mlen; i++) { workspace[0*mlen + i] = (mlen-i <= a[0] ? a[mlen-i] : 0); workspace[1*mlen + i] = (mlen-i <= b[0] ? b[mlen-i] : 0); @@ -763,14 +787,14 @@ char *bignum_decimal(Bignum x) { i = ssh1_bignum_bitcount(x); ndigits = (28*i + 92)/93; /* multiply by 28/93 and round up */ ndigits++; /* allow for trailing \0 */ - ret = malloc(ndigits); + ret = smalloc(ndigits); /* * Now allocate some workspace to hold the binary form as we * repeatedly divide it by ten. Initialise this to the * big-endian form of the number. */ - workspace = malloc(sizeof(unsigned short) * x[0]); + workspace = smalloc(sizeof(unsigned short) * x[0]); for (i = 0; i < x[0]; i++) workspace[i] = x[x[0] - i];