crypto-bn-cpp

Cross-platform library of big number in C++.

Important Update

The input of the random number generator changes from "bytes" to "bits".

The new generators:

safeheron::bignum::BN RandomBN(size_t bits);
safeheron::bignum::BN RandomBNStrict(size_t bits);
safeheron::bignum::BN RandomPrime(size_t bits);
safeheron::bignum::BN RandomPrimeStrict(size_t bits);
safeheron::bignum::BN RandomSafePrime(size_t bits);
safeheron::bignum::BN RandomSafePrimeStrict(size_t bits);

The old generators:

safeheron::bignum::BN RandomBN(size_t byteSize);
safeheron::bignum::BN RandomBNStrict(size_t byteSize);
safeheron::bignum::BN RandomPrime(size_t byteSize);
safeheron::bignum::BN RandomPrimeStrict(size_t byteSize);
safeheron::bignum::BN RandomSafePrime(size_t byteSize);
safeheron::bignum::BN RandomSafePrimeStrict(size_t byteSize);

Along with the update, all the usage should update too, otherwise there is a risk..

For example, we used to get a 256-bits number like this before:

    BN r = safeheron::bignum::BN RandomBN(256 / 8);

Now we must invoke the generator like this:

    BN r = safeheron::bignum::BN RandomBN(256);

If usage don't update then you will get a small number with 32-bits length, and then it could easily be guessed out by the adversary.

Prerequisites

OpenSSL. See the OpenSSL Installation Instructions
GoogleTest. You need it to compile and run test cases. See the GoogleTest Installation Instructions

Build and Install

Linux and Mac are supported now. After obtaining the Source, have a look at the installation script.

git clone https://gitlab.com/safeheron/algogroup/crypto-bn-cpp.git
cd crypto-bn-cpp
mkdir build && cd build
# Run "cmake .. -DOPENSSL_ROOT_DIR=Your-Root-Directory-of-OPENSSL" instead of the command below on Mac OS.
# Turn on the switcher to enable tests; by default, turn off it if you don't wanna to build the test cases.
cmake .. -DENABLE_TESTS=ON
make
make test
sudo make install

More platforms such as Windows would be supported soon.

To start using crypto-bn-cpp

CMake

CMake is your best option. It supports building on Linux, MacOS and Windows (soon) but also has a good chance of working on other platforms (no promises!). cmake has good support for crosscompiling and can be used for targeting the Android platform.

To build crypto-bn-cpp from source, follow the BUILDING guide.

The canonical way to discover dependencies in CMake is the find_package command.

project(XXXX)

set(CMAKE_CXX_STANDARD 11)
set(CMAKE_BUILD_TYPE "Release")

find_package(OpenSSL REQUIRED)
find_package(CryptoBN REQUIRED)

add_executable(${PROJECT_NAME} XXXX.cpp)
target_include_directories(${PROJECT_NAME} PUBLIC
    ${CryptoBN_INCLUDE_DIRS}
)

target_link_libraries(${PROJECT_NAME} PUBLIC
    CryptoBN
    OpenSSL::Crypto
    pthread 
    -ldl
)

Using class BN

#include "crypto-bn/bn.h"

using safeheron::bignum::BN;

int main(){
    BN n1 = BN::FromDecStr("351236171680578937197272793988364310158344798196852032811622206579");
    BN n2 = BN::FromDecStr("531137992816767098689588206552468627329593117727031923199444138200");
    BN n3 = BN::FromDecStr("206552468627329593117727031923199444195931177270319231994441382004");
    
    BN n4 = (n1 * n2) % n3;
    
    std::cout << "n4" << n4.Inspect() << std::endl;
    
    return 0;
}

Generate Random BN

#include "crypto-bn/bn.h"

using safeheron::bignum::BN;
int main(){
    // Create a BN which is 256 bits (32 bytes) long. 
    BN n = safeheron::rand::RandomBN(256);
    max = n;
    n.ToHexStr(s);
    std::cout << s << std::endl;
    return 0;
}

Usage

Constructor

BN() - Construct a BN object and initialized it with 0.

BN(long i) - Construct a BN object and initialized it with word i.

BN(const char * str, int base) - Construct a BN objet and initialized it with str on specified base.

BN(const BN & num) - A copy constructor.

BN(BN && num ) A move constructor.

operator=(BN && num) - A move assignment.

operator=(const BN & num ) - A copy assignment.

Bit operations

SetBit(unsigned long bit_index) - Set bits for this BN

ClearBit(unsigned long bit_index) - Clean bits for BN.

IsBitSet(unsigned long bit_index) - Return true if this BN bit is set

BitLength() - Return bits size.

ByteLength() - Return bytes size.

operator<<(unsigned long ui) - Shift this to left by ui bits, and return the result

operator<<=(unsigned long ui) - Shift this to left by ui bits

operator>>(unsigned long ui) - Shift this to right by ui bits, and return the result

operator>>=(unsigned long ui) - Shift this to right by ui bits

Convertors

FromBytesBE(const uint8_t * buf, int len) - [static] Construct a BN object from byte buffer, in big endian

FromBytesBE(std::string & buf) - [static] Construct a BN object from byte string, in big endian

FromBytesLE(const uint8_t * buf, int len) - [static] Construct a BN object from byte buffer, in little endian

FromBytesLE(std::string & buf) - [static] - Construct a BN object from byte string, in little endian

FromDecStr(const char * str ) - [static] Construct a BN object from DEC char*

FromDecStr(const std::string & str) - [static] Construct a BN object from DEC string

FromHexStr(const char * str) - [static] Construct a BN object from HEX char*

FromHexStr(const std::string & str) - [static] Construct a BN object from HEX string

ToBytes32BE(std::string & buf) - Convert this BN to 32 bytes buff, in big endian

ToBytes32BE(uint8_t * buf32, int blen = 32) - Convert this BN to 32 bytes string, in big endian

ToBytes32LE(std::string & buf ) - Convert this BN to 32 bytes buff, in little endian

ToBytes32LE(uint8_t * buf32, int blen = 32) - Convert this BN to 32 bytes string, in little endian

ToBytesBE(std::string & buf ) - Convert this BN to bytes string, in big endian

ToBytesLE(std::string & buf ) - Convert this BN to bytes string, in little endian

ToDecStr(std::string & str ) - Convert this BN bits to a DEC string

ToHexStr(std::string & str ) - Convert this BN bits to a HEX string

Arithmetics

operator+(const BN & num) - Add the BN num with this, and return the result

operator+(long si) - Add the long value si with this, and return the result

operator+=(const BN & num) - Add the BN num with this

operator+=(long si) - Add the long value si with this

operator-(const BN & num) - Sub the BN num from this, and return the result

operator-(long si) - Sub the long value si from this, and return the result

operator-=(const BN & num) - Sub the BN num from this

operator-=(long si) - Sub the long value si from this

operator*(const BN & num) - Mul the BN num with this, and return the result

operator*(long si) - Mul the long value si with this, and return the result

operator*=(const BN & num) - Mul the BN num with this

operator*=(long si) - Mul the long value si with this

operator/(const BN & num) - Div the BN num with this, and return the result

operator/(long si) - Div the long value si with this, and return the result

operator/=(const BN & num) - Div the BN num by this

operator/=(long si) - Div the long value si with this

operator%(const BN & num) - Mod the BN num with this, and return the result

operator%(unsigned long ui) - Mod the ULONG value ui with this, and return the result

Neg() - Return the negative of this

Comparison

operator==(const BN & num) - Return true if this._bn == num._bn

operator==(long num) - Return true if this._bn == num._bn

operator!=(const BN & num) - Return true if this._bn != num._bn

operator!=(long num) - Return true if this._bn != num._bn

operator<=(const BN & num) - Return true if this._bn <= num._bn

operator<=(long si) - Return true if this._bn <= si

operator<(const BN & num) - Return true if this._bn < num._bn

operator<(long si) - Return true if this._bn < si

operator>(const BN & num) - Return true if this._bn > num._bn

operator>(long si) - Return true if this._bn > si

operator>=(const BN & num) - Return true if this._bn >= num._bn

operator>=(long si) - Return true if this._bn >= si

Auxiliary

IsEven() - Return true if this BN is a even number

IsNeg() - Return true if this BN is a negative number

IsOdd() - Return true if this BN is an odd number

IsZero() - Return true if this BN is 0

Max(const BN & a, const BN & b) - [static] Return the max one between a and b

Min(const BN & a, const BN & b) - [static] Return the min one between a and b

Swap(BN & a, BN & b) - [static] Swap the values between a and b

Number Theory

IsProbablyPrime() - Return true is this is a prime, otherwise return false

Div(const BN & d, BN & q, BN & r) - Return quotient q = this / d and remainder r = this % d.

SqrtM(const BN & p) - Get square root on modulo m Return 'r' such that r^2 == this (mod p),

ExistSqrtM(const BN & p) - Return sqrt mod is exist or not.

Gcd(const BN & n) - Return the greatest common divisor of this and n

Inspect(int base = 16) - Return the string of this BN

InvM(const BN & m) - Return the inverse of (this modulo m) Compute the inverse modulo mod. Be careful, mode must be prime!!!

Lcm(const BN & n) const Return the least common multiple of this and n. lcm(a, b) = ab/gcd(a,b))

PowM(const BN & y, const BN & m) - Return the y-th power of this and modulo m r = (this ^ y) % m

Some features

Refer to Some-Features.md

Development Process & Contact

This library is maintained by Safeheron. Contributions are highly welcomed! Besides GitHub issues and PRs, feel free to reach out by mail.

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README.md

README.md

crypto-bn-cpp

Important Update

Prerequisites

Build and Install

To start using crypto-bn-cpp

CMake

Using class BN

Generate Random BN

Usage

Constructor

Bit operations

Convertors

Arithmetics

Comparison

Auxiliary

Number Theory

Some features

Development Process & Contact

License

Files

README.md

Latest commit

History

README.md

File metadata and controls

crypto-bn-cpp

Important Update

Prerequisites

Build and Install

To start using crypto-bn-cpp

CMake

Using class BN

Generate Random BN

Usage

Constructor

Bit operations

Convertors

Arithmetics

Comparison

Auxiliary

Number Theory

Some features

Development Process & Contact

License