diff options
Diffstat (limited to 'src/math')
| -rw-r--r-- | src/math/bigint/bigint.h | 448 |
1 files changed, 397 insertions, 51 deletions
diff --git a/src/math/bigint/bigint.h b/src/math/bigint/bigint.h index bb1d7ef7b..ec3c1cbe3 100644 --- a/src/math/bigint/bigint.h +++ b/src/math/bigint/bigint.h @@ -1,6 +1,7 @@ /************************************************* * BigInt Header File * * (C) 1999-2008 Jack Lloyd * +* 2007 FlexSecure * *************************************************/ #ifndef BOTAN_BIGINT_H__ @@ -13,41 +14,168 @@ namespace Botan { -/************************************************* -* BigInt * -*************************************************/ +/** + * Big Integer representation. This class defines an integer type, + * that can be very big. Additionally some helper functions are + * defined to work more comfortably. + * + */ class BOTAN_DLL BigInt { public: + /** + * Base-Enumerator (currently 8,10,16 and 256 are defined) + */ enum Base { Octal = 8, Decimal = 10, Hexadecimal = 16, Binary = 256 }; + + /** + * Sign symbol definitions for positive and negative numbers + */ enum Sign { Negative = 0, Positive = 1 }; + + /** + * Number types (Powers of 2) + */ enum NumberType { Power2 }; + /** + * DivideByZero Exception + */ struct DivideByZero : public Exception { DivideByZero() : Exception("BigInt divide by zero") {} }; - BigInt& operator+=(const BigInt&); - BigInt& operator-=(const BigInt&); - - BigInt& operator*=(const BigInt&); - BigInt& operator/=(const BigInt&); - BigInt& operator%=(const BigInt&); - word operator%=(word); - BigInt& operator<<=(u32bit); - BigInt& operator>>=(u32bit); - + /************* + * operators * + *************/ + + /** + * += Operator + * @param y the BigInt to add to the local value + */ + BigInt& operator+=(const BigInt& y); + + /** + * -= Operator + * @param y the BigInt to subtract from the local value + */ + BigInt& operator-=(const BigInt& y); + + /** + * *= Operator + * @param y the BigInt to multiply with the local value + */ + BigInt& operator*=(const BigInt& y); + + /** + * /= Operator + * @param y the BigInt to divide the local value by + */ + BigInt& operator/=(const BigInt& y); + + /** + * %= Operator, modulo operator. + * @param y the modulus to reduce the local value by + */ + BigInt& operator%=(const BigInt& y); + + /** + * %= Operator + * @param y the modulus (word) to reduce the local value by + */ + word operator%=(word y); + + /** + * <<= Operator + * @param y the amount of bits to shift the local value left + */ + BigInt& operator<<=(u32bit y); + + /** + * >>= Operator + * @param y the amount of bits to shift the local value right + */ + BigInt& operator>>=(u32bit y); + + /** + * ++ Operator + */ BigInt& operator++() { return (*this += 1); } + + /** + * -- Operator + */ BigInt& operator--() { return (*this -= 1); } + + /** + * ++ Operator (postfix) + */ BigInt operator++(int) { BigInt x = (*this); ++(*this); return x; } + + /** + * -- Operator (postfix) + */ BigInt operator--(int) { BigInt x = (*this); --(*this); return x; } + /** + * - Operator + */ BigInt operator-() const; + + /** + * ! Operator + */ bool operator !() const { return (!is_nonzero()); } - s32bit cmp(const BigInt&, bool = true) const; + /** + * [] Operator (array access) + */ + word& operator[](u32bit i) { return reg[i]; } + + /** + * [] Operator (array access) + */ + word operator[](u32bit i) const { return reg[i]; } + + /** + * Zeroize the BigInt + */ + void clear() { get_reg().clear(); } + + /************* + * functions * + ************/ + + /** + * Compare *this to another BigInt. + * @param n the BigInt value to compare to the local value. + * @param check_signs Include sign in comparison? + * @result if (this<n) return -1, if (this>n) return 1, if both + * values are identical return 0. + */ + s32bit cmp(const BigInt& n, bool check_signs = true) const; + + /** + * Test if the integer has an even value + * @result true, if the integer an even value, false otherwise + */ bool is_even() const { return (get_bit(0) == 0); } + + /** + * Test if the integer has an odd value + * @result true, if the integer an odd value, false otherwise + */ bool is_odd() const { return (get_bit(0) == 1); } + /** + * Test if the integer is not zero. + * @result true, if the integer has a non-zero value, false otherwise + */ + bool is_nonzero() const { return (!is_zero()); } + + /** + * Test if the integer is zero. + * @result true, if the integer has the value zero, false otherwise + */ bool is_zero() const { const u32bit sw = sig_words(); @@ -58,32 +186,108 @@ class BOTAN_DLL BigInt return true; } - bool is_nonzero() const { return (!is_zero()); } - - void set_bit(u32bit); - void clear_bit(u32bit); - void mask_bits(u32bit); + /** + * Set bit at specified position + * @param n bit position to set + */ + void set_bit(u32bit n); + + /** + * Clear bit at specified position + * @param n bit position to clear + */ + void clear_bit(u32bit n); + + /** + * Clear all but the lowest n bits + * @param n amount of bits to keep + */ + void mask_bits(u32bit n); + + /** + * Return bit value at specified position + * @param n the bit offset to test + * @result true, if the bit at position n is set, false otherwise + */ + bool get_bit(u32bit n) const; + + /** + * Return (a maximum of) 32 bits of the complete value + * @param offset the offset to start extracting + * @param length amount of bits to extract (starting at offset) + * @result the integer extracted from the register starting at offset with specified length + */ + u32bit get_substring(u32bit offset, u32bit length) const; - bool get_bit(u32bit) const; - u32bit get_substring(u32bit, u32bit) const; byte byte_at(u32bit) const; - // same as operator[], remove this + /** + * Return the word at a specified position of the internal register + * @param n position in the register + * @return the value at position n + */ word word_at(u32bit n) const - { return ((n < size()) ? get_reg()[n] : 0); } - + { return ((n < size()) ? reg[n] : 0); } + + /** + * Return the integer as an unsigned 32bit-integer-value. + * If the value is negative OR to big to be stored in 32bits, this function + * will throw an exception. + * @result a 32bit-integer + */ u32bit to_u32bit() const; + /** + * Tests if the sign of the integer is negative. + * @result true, if the integer has a negative sign, + */ bool is_negative() const { return (sign() == Negative); } + + /** + * Tests if the sign of the integer is positive. + * @result true, if the integer has a positive sign, + */ bool is_positive() const { return (sign() == Positive); } - Sign sign() const { return (signedness); } + + /** + * Return the sign of the integer + * @result the sign of the integer + */ + Sign sign() const { return (signedness); } + + /** + * Return the opposite sign of the represented integer value + * @result the opposite sign of the represented integer value + */ Sign reverse_sign() const; + + /** + * Flip (change!) the sign of the integer to its opposite value + */ void flip_sign(); - void set_sign(Sign); + + /** + * Set sign of the integer + * @param sign new Sign to set + */ + void set_sign(Sign sign); + + /** + * Give absolute (positive) value of the integer + * @result absolute (positive) value of the integer + */ BigInt abs() const; + /** + * Give size of internal register + * @result size of internal register in words + */ u32bit size() const { return get_reg().size(); } + /** + * Give significant words of the represented integer value + * @result significant words of the represented integer value + */ u32bit sig_words() const { const word* x = reg.begin(); @@ -94,46 +298,188 @@ class BOTAN_DLL BigInt return sig; } + /** + * Give byte-length of the integer + * @result byte-length of the represented integer value + */ u32bit bytes() const; + + /** + * Get the bit-length of the integer. + * @result bit-length of the represented integer value + */ u32bit bits() const; + /** + * Return a pointer to the big integer word register. + * @result a pointer to the start of the internal register of + * the integer value + */ const word* data() const { return reg.begin(); } - SecureVector<word>& get_reg() { return reg; } - const SecureVector<word>& get_reg() const { return reg; } - void grow_reg(u32bit); - void grow_to(u32bit); + /** + * return a reference to the internal register containing the value + * @result a reference to the word-array (SecureVector<word>) + * with the internal register value (containing the integer + * value) + */ + SecureVector<word>& get_reg() { return reg; } - word& operator[](u32bit i) { return reg[i]; } - word operator[](u32bit i) const { return reg[i]; } - void clear() { get_reg().clear(); } + /** + * return a const reference to the internal register containing the value + * @result a const reference to the word-array (SecureVector<word>) + * with the internal register value (containing the integer + * value) + */ + const SecureVector<word>& get_reg() const { return reg; } - void randomize(RandomNumberGenerator& rng, u32bit n); + /** + * Increase internal register buffer by n words + * @param n increase by n words + */ + void grow_reg(u32bit n); + + void grow_to(u32bit n); + + /** + * Fill BigInt with a random number with size of bitsize + * @param rng the random number generator to use + * @param bitsize number of bits the created random value should have + */ + void randomize(RandomNumberGenerator& rng, u32bit bitsize = 0); + + /** + * Store BigInt-value in a given byte array + * @param buf destination byte array for the integer value + */ + void binary_encode(byte buf[]) const; + + /** + * Read integer value from a byte array with given size + * @param buf byte array buffer containing the integer + * @param length size of buf + */ + void binary_decode(const byte buf[], u32bit length); + + /** + * Read integer value from a byte array (MemoryRegion<byte>) + * @param buf the BigInt value to compare to the local value. + */ + void binary_decode(const MemoryRegion<byte>& buf); - void binary_encode(byte[]) const; - void binary_decode(const byte[], u32bit); - void binary_decode(const MemoryRegion<byte>&); u32bit encoded_size(Base = Binary) const; - static BigInt random_integer(RandomNumberGenerator&, - const BigInt&, const BigInt&); + /** + @param rng a random number generator + @result a random integer between min and max + */ + static BigInt random_integer(RandomNumberGenerator& rng, + const BigInt& min, const BigInt& max); + + /** + * Encode the integer value from a BigInt to a SecureVector of bytes + * @param n the BigInt to use as integer source + * @param base number-base of resulting byte array representation + * @result SecureVector of bytes containing the integer with given base + */ + static SecureVector<byte> encode(const BigInt& n, Base base = Binary); + + /** + * Encode the integer value from a BigInt to a byte array + * @param buf destination byte array for the encoded integer + * value with given base + * @param n the BigInt to use as integer source + * @param base number-base of resulting byte array representation + */ + static void encode(byte buf[], const BigInt& n, Base base = Binary); + + /** + * Create a BigInt from an integer in a byte array + * @param buf the BigInt value to compare to the local value. + * @param length size of buf + * @param base number-base of the integer in buf + * @result BigInt-representing the given integer read from the byte array + */ + static BigInt decode(const byte buf[], u32bit length, Base base = Binary); - static SecureVector<byte> encode(const BigInt&, Base = Binary); - static void encode(byte[], const BigInt&, Base = Binary); - static BigInt decode(const byte[], u32bit, Base = Binary); static BigInt decode(const MemoryRegion<byte>&, Base = Binary); - static SecureVector<byte> encode_1363(const BigInt&, u32bit); - - void swap(BigInt&); + /** + * Encode a Big Integer to a byte array according to IEEE1363. + * @param n the Big Integer to encode + * @param bytes the length of the resulting SecureVector<byte> + * @result a SecureVector<byte> containing the encoded Big Integer + */ + static SecureVector<byte> encode_1363(const BigInt& n, u32bit bytes); + + /** + * Swap BigInt-value with given BigInt. + * @param bigint the BigInt to swap values with + */ + void swap(BigInt& bigint); + + /** + * constructors + */ + + /** + * Create empty BigInt + */ BigInt() { signedness = Positive; } - BigInt(u64bit); - BigInt(const BigInt&); - BigInt(const std::string&); - BigInt(const byte[], u32bit, Base = Binary); + + /** + * Create BigInt from 64bit-Integer value + * @param n 64bit-integer + */ + BigInt(u64bit n); + + /** + * Copy-Constructor: clone given BigInt + * @param bigint the BigInt to clone + */ + BigInt(const BigInt& bigint); + + /** + * Create BigInt from a string. + * If the string starts with 0x the rest of the string will be + * interpreted as hexadecimal digits. + * If the string starts with 0 and the second character is NOT + * an 'x' the string will be interpreted as octal digits. + * If the string starts with non-zero digit, it will be + * interpreted as a decimal number. + * @param str the string to parse for an integer value + */ + BigInt(const std::string& str); + + /** + * Create a BigInt from an integer in a byte array + * @param buf the BigInt value to compare to the local value. + * @param length size of buf + * @param base number-base of the integer in buf + */ + BigInt(const byte buf[], u32bit length, Base base = Binary); + + /** + * Create a random BigInt of the specified size + * @param rng random number generator + * @param bits size in bits + */ BigInt(RandomNumberGenerator& rng, u32bit bits); - BigInt(Sign, u32bit); - BigInt(NumberType, u32bit); + + /** + * Create BigInt from unsigned 32 bit integer value and an + * also specify the sign of the value + * @param n integer value + */ + BigInt(Sign, u32bit n); + + /** + * Create a number of the specified type and size + * @param type the type of number to create + * @param n the size + */ + BigInt(NumberType type, u32bit n); + private: SecureVector<word> reg; Sign signedness; |