diff options
Diffstat (limited to 'openssl-1.1.0h/crypto/bn/bn_word.c')
| -rw-r--r-- | openssl-1.1.0h/crypto/bn/bn_word.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/openssl-1.1.0h/crypto/bn/bn_word.c b/openssl-1.1.0h/crypto/bn/bn_word.c new file mode 100644 index 0000000..1af13a5 --- /dev/null +++ b/openssl-1.1.0h/crypto/bn/bn_word.c @@ -0,0 +1,201 @@ +/* + * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved. + * + * Licensed under the OpenSSL license (the "License"). You may not use + * this file except in compliance with the License. You can obtain a copy + * in the file LICENSE in the source distribution or at + * https://www.openssl.org/source/license.html + */ + +#include "internal/cryptlib.h" +#include "bn_lcl.h" + +BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w) +{ +#ifndef BN_LLONG + BN_ULONG ret = 0; +#else + BN_ULLONG ret = 0; +#endif + int i; + + if (w == 0) + return (BN_ULONG)-1; + +#ifndef BN_LLONG + /* + * If |w| is too long and we don't have BN_ULLONG then we need to fall + * back to using BN_div_word + */ + if (w > ((BN_ULONG)1 << BN_BITS4)) { + BIGNUM *tmp = BN_dup(a); + if (tmp == NULL) + return (BN_ULONG)-1; + + ret = BN_div_word(tmp, w); + BN_free(tmp); + + return ret; + } +#endif + + bn_check_top(a); + w &= BN_MASK2; + for (i = a->top - 1; i >= 0; i--) { +#ifndef BN_LLONG + /* + * We can assume here that | w <= ((BN_ULONG)1 << BN_BITS4) | and so + * | ret < ((BN_ULONG)1 << BN_BITS4) | and therefore the shifts here are + * safe and will not overflow + */ + ret = ((ret << BN_BITS4) | ((a->d[i] >> BN_BITS4) & BN_MASK2l)) % w; + ret = ((ret << BN_BITS4) | (a->d[i] & BN_MASK2l)) % w; +#else + ret = (BN_ULLONG) (((ret << (BN_ULLONG) BN_BITS2) | a->d[i]) % + (BN_ULLONG) w); +#endif + } + return ((BN_ULONG)ret); +} + +BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w) +{ + BN_ULONG ret = 0; + int i, j; + + bn_check_top(a); + w &= BN_MASK2; + + if (!w) + /* actually this an error (division by zero) */ + return (BN_ULONG)-1; + if (a->top == 0) + return 0; + + /* normalize input (so bn_div_words doesn't complain) */ + j = BN_BITS2 - BN_num_bits_word(w); + w <<= j; + if (!BN_lshift(a, a, j)) + return (BN_ULONG)-1; + + for (i = a->top - 1; i >= 0; i--) { + BN_ULONG l, d; + + l = a->d[i]; + d = bn_div_words(ret, l, w); + ret = (l - ((d * w) & BN_MASK2)) & BN_MASK2; + a->d[i] = d; + } + if ((a->top > 0) && (a->d[a->top - 1] == 0)) + a->top--; + ret >>= j; + if (!a->top) + a->neg = 0; /* don't allow negative zero */ + bn_check_top(a); + return (ret); +} + +int BN_add_word(BIGNUM *a, BN_ULONG w) +{ + BN_ULONG l; + int i; + + bn_check_top(a); + w &= BN_MASK2; + + /* degenerate case: w is zero */ + if (!w) + return 1; + /* degenerate case: a is zero */ + if (BN_is_zero(a)) + return BN_set_word(a, w); + /* handle 'a' when negative */ + if (a->neg) { + a->neg = 0; + i = BN_sub_word(a, w); + if (!BN_is_zero(a)) + a->neg = !(a->neg); + return (i); + } + for (i = 0; w != 0 && i < a->top; i++) { + a->d[i] = l = (a->d[i] + w) & BN_MASK2; + w = (w > l) ? 1 : 0; + } + if (w && i == a->top) { + if (bn_wexpand(a, a->top + 1) == NULL) + return 0; + a->top++; + a->d[i] = w; + } + bn_check_top(a); + return (1); +} + +int BN_sub_word(BIGNUM *a, BN_ULONG w) +{ + int i; + + bn_check_top(a); + w &= BN_MASK2; + + /* degenerate case: w is zero */ + if (!w) + return 1; + /* degenerate case: a is zero */ + if (BN_is_zero(a)) { + i = BN_set_word(a, w); + if (i != 0) + BN_set_negative(a, 1); + return i; + } + /* handle 'a' when negative */ + if (a->neg) { + a->neg = 0; + i = BN_add_word(a, w); + a->neg = 1; + return (i); + } + + if ((a->top == 1) && (a->d[0] < w)) { + a->d[0] = w - a->d[0]; + a->neg = 1; + return (1); + } + i = 0; + for (;;) { + if (a->d[i] >= w) { + a->d[i] -= w; + break; + } else { + a->d[i] = (a->d[i] - w) & BN_MASK2; + i++; + w = 1; + } + } + if ((a->d[i] == 0) && (i == (a->top - 1))) + a->top--; + bn_check_top(a); + return (1); +} + +int BN_mul_word(BIGNUM *a, BN_ULONG w) +{ + BN_ULONG ll; + + bn_check_top(a); + w &= BN_MASK2; + if (a->top) { + if (w == 0) + BN_zero(a); + else { + ll = bn_mul_words(a->d, a->d, a->top, w); + if (ll) { + if (bn_wexpand(a, a->top + 1) == NULL) + return (0); + a->d[a->top++] = ll; + } + } + } + bn_check_top(a); + return (1); +} |