aboutsummaryrefslogtreecommitdiffstats
path: root/src/math
diff options
context:
space:
mode:
authorlloyd <[email protected]>2011-05-10 13:03:04 +0000
committerlloyd <[email protected]>2011-05-10 13:03:04 +0000
commit4cf2e6a56d58547d241fb8cc42a95924add97665 (patch)
tree78d192d7a703e2e3139458649af8bc2bc5628dcd /src/math
parent37b1ca2b6e12fc099e9afdc80c6de9da111eb657 (diff)
Add back BigInt::to_u32bit
Fix BigInt::get_substring when length is equal to 32 - an overflow would cause the mask to be equal to 0 thus producing nothing at all. Disable CVC by default, it's not ready for prime time in any sense.
Diffstat (limited to 'src/math')
-rw-r--r--src/math/bigint/bigint.cpp55
-rw-r--r--src/math/bigint/bigint.h7
2 files changed, 45 insertions, 17 deletions
diff --git a/src/math/bigint/bigint.cpp b/src/math/bigint/bigint.cpp
index 6ee5a75e3..38838e286 100644
--- a/src/math/bigint/bigint.cpp
+++ b/src/math/bigint/bigint.cpp
@@ -1,6 +1,6 @@
/*
* BigInt Base
-* (C) 1999-2008 Jack Lloyd
+* (C) 1999-2011 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
@@ -10,6 +10,7 @@
#include <botan/get_byte.h>
#include <botan/parsing.h>
#include <botan/internal/rounding.h>
+#include <stdio.h>
namespace Botan {
@@ -26,8 +27,8 @@ BigInt::BigInt(u64bit n)
const size_t limbs_needed = sizeof(u64bit) / sizeof(word);
reg.resize(4*limbs_needed);
- for(size_t j = 0; j != limbs_needed; ++j)
- reg[j] = ((n >> (j*MP_WORD_BITS)) & MP_WORD_MASK);
+ for(size_t i = 0; i != limbs_needed; ++i)
+ reg[i] = ((n >> (i*MP_WORD_BITS)) & MP_WORD_MASK);
}
/*
@@ -171,16 +172,35 @@ u32bit BigInt::get_substring(size_t offset, size_t length) const
throw Invalid_Argument("BigInt::get_substring: Substring size too big");
u64bit piece = 0;
- for(size_t j = 0; j != 8; ++j)
- piece = (piece << 8) | byte_at((offset / 8) + (7-j));
+ for(size_t i = 0; i != 8; ++i)
+ {
+ const byte part = byte_at((offset / 8) + (7-i));
+ piece = (piece << 8) | part;
+ }
- u64bit mask = (1 << length) - 1;
- size_t shift = (offset % 8);
+ const u64bit mask = (static_cast<u64bit>(1) << length) - 1;
+ const size_t shift = (offset % 8);
return static_cast<u32bit>((piece >> shift) & mask);
}
/*
+* Convert this number to a u32bit, if possible
+*/
+u32bit BigInt::to_u32bit() const
+ {
+ if(is_negative())
+ throw Encoding_Error("BigInt::to_u32bit: Number is negative");
+ if(bits() >= 32)
+ throw Encoding_Error("BigInt::to_u32bit: Number is too big to convert");
+
+ u32bit out = 0;
+ for(u32bit j = 0; j != 4; ++j)
+ out = (out << 8) | byte_at(3-j);
+ return out;
+ }
+
+/*
* Set bit number n
*/
void BigInt::set_bit(size_t n)
@@ -214,8 +234,8 @@ void BigInt::mask_bits(size_t n)
const word mask = (static_cast<word>(1) << (n % MP_WORD_BITS)) - 1;
if(top_word < size())
- for(size_t j = top_word + 1; j != size(); ++j)
- reg[j] = 0;
+ for(size_t i = top_word + 1; i != size(); ++i)
+ reg[i] = 0;
reg[top_word] &= mask;
}
@@ -321,8 +341,8 @@ BigInt BigInt::abs() const
void BigInt::binary_encode(byte output[]) const
{
const size_t sig_bytes = bytes();
- for(size_t j = 0; j != sig_bytes; ++j)
- output[sig_bytes-j-1] = byte_at(j);
+ for(size_t i = 0; i != sig_bytes; ++i)
+ output[sig_bytes-i-1] = byte_at(i);
}
/*
@@ -335,14 +355,15 @@ void BigInt::binary_decode(const byte buf[], size_t length)
clear();
reg.resize(round_up<size_t>((length / WORD_BYTES) + 1, 8));
- for(size_t j = 0; j != length / WORD_BYTES; ++j)
+ for(size_t i = 0; i != length / WORD_BYTES; ++i)
{
- size_t top = length - WORD_BYTES*j;
- for(size_t k = WORD_BYTES; k > 0; --k)
- reg[j] = (reg[j] << 8) | buf[top - k];
+ const size_t top = length - WORD_BYTES*i;
+ for(size_t j = WORD_BYTES; j > 0; --j)
+ reg[i] = (reg[i] << 8) | buf[top - j];
}
- for(size_t j = 0; j != length % WORD_BYTES; ++j)
- reg[length / WORD_BYTES] = (reg[length / WORD_BYTES] << 8) | buf[j];
+
+ for(size_t i = 0; i != length % WORD_BYTES; ++i)
+ reg[length / WORD_BYTES] = (reg[length / WORD_BYTES] << 8) | buf[i];
}
/*
diff --git a/src/math/bigint/bigint.h b/src/math/bigint/bigint.h
index 12a7f1701..87c7cb766 100644
--- a/src/math/bigint/bigint.h
+++ b/src/math/bigint/bigint.h
@@ -218,6 +218,13 @@ class BOTAN_DLL BigInt
u32bit get_substring(size_t offset, size_t length) const;
/**
+ * Convert this value into a u32bit, if it is in the range
+ * [0 ... 2**32-1], or otherwise throw an exception.
+ * @result the value as a u32bit if conversion is possible
+ */
+ u32bit to_u32bit() const;
+
+ /**
* @param n the offset to get a byte from
* @result byte at offset n
*/