## ecgen [](https://travis-ci.org/J08nY/ecgen) [](https://github.com/J08nY/ecgen/releases/latest) [](https://codecov.io/gh/J08nY/ecgen)
Tool for generating Elliptic curve domain parameters.
### Usage
ecgen --fp/--f2m BITS
#### Field specification
- `--f2m` Binary field.
- `--fp` Prime field.
#### Generation methods
- `--anomalous` Generate an anomalous curve (of trace one, with field order equal to curve order).
- `-b / --brainpool[=SEED]`Generate a curve using the Brainpool verifiably pseudorandom algorithm from the original paper.
- `--brainpool-rfc[=SEED]` Generate a curve using the Brainpool verifiably pseudorandom algorithm as per RFC 5639.
- `-i / --invalid` Generate a set of invalid curves, for a given curve (using Invalid curve algorithm).
- `-n / --order=ORDER` Generate a curve with given `ORDER` (using Complex Multiplication). **TODO - NOT IMPLEMENTED**
- `-s / --ansi[=SEED]` Generate a curve from `SEED` (ANSI X9.62 verifiable procedure).
- `--twist` Generate a twist of a given curve.
#### Generation options
- `-c / --count=COUNT` Generate multiple curves.
- `-k / --cofactor=VALUE` Generate a curve with cofactor of `VALUE`.
- `-K / --koblitz[=A]` Generate a Koblitz curve (a in {0, 1}, b = 1).
- `-p / --prime` Generate a curve with prime order.
- `--points=TYPE` Generate points of given `TYPE` (random/prime/all/nonprime/none).
- `-r / --random` Generate a random curve (using Random approach).
- `-u / --unique` Generate a curve with only one generator.
#### IO options
- `-f / --input=FILE` Input from `FILE`.
- `-o / --output=FILE` Output into `FILE`. Overwrites any existing file!
- `-a / --append` Append to output file (don't overwrite).
- `-v / --verbose[=FILE]` Verbose logging (to stdout or `FILE`).
#### Other
- `-d / --data-dir=DIR` Set PARI/GP data directory (containing seadata package).
- `-m / --memory=SIZE` Use PARI stack of `SIZE` (can have suffix k/m/g).
- `--threads=NUM` Use `NUM` threads.
- `--thread-stack=SIZE` Use PARI stack of `SIZE` (per thread, can have suffix k/m/g).
- `--timeout=TIME` Timeout computation of a curve parameter after `TIME` (can have suffix s/m/h/d).
#### Examples
Generate a prime field, uniquely generated, prime order, 192-bit curve, don't ask for input try random values:
> ecgen --fp -u -p -r 192
Generate 5 random, binary field, 163-bit curves:
> ecgen --f2m -r -c5 163
Generate invalid curves to a file, for a given prime field 192-bit curve:
> ecgen --fp -i --output=invalid.json 192
p:
a:
b:
Generate a prime field, uniquely generated, prime order curve, don't ask for input try random values, verbose output *(shown with example output here)*:
> ecgen --fp -u -p -r -v 128
+++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-++++-+++++++
{
"field": {
"p": "0xa5393890f26881d94ad670171ce67b79"
},
"a": "0x9c083973bdca36ea71078bbaabab4947",
"b": "0x3d986a0206bfbe1ba62c858df54385e9",
"order": "0xa5393890f26881d9394aece3bc2d9b47",
"subgroups": [
{
"x": "0x5acc17d6a44e8f8d30e877f4fef8712f",
"y": "0x6864dd64e80609abd1797c8de1febb9f",
"order": "0xa5393890f26881d9394aece3bc2d9b47",
"cofactor": "0x1",
"points": [
{
"x": "0x9c7878930ddf5bfb705102f652754e7",
"y": "0x4b15a7bb808cb3579fd4c2ce42f628de",
"order": "0xa5393890f26881d9394aece3bc2d9b47"
}
]
}
]
}
### Docs
See [docs](docs/readme.md). Also:
make docs
for Doxygen.
### Generation methods
Three different EC curve parameters generation methods are implemented.
[Efficient Algorithms for Generating Elliptic Curves over Finite Fields Suitable for Use in Cryptography - [Baier]](https://www.cdc.informatik.tu-darmstadt.de/reports/reports/harald_baier.diss.pdf)
[Generation Methods of Elliptic Curves - [Baier, Buchmann]](https://www.ipa.go.jp/security/enc/CRYPTREC/fy15/doc/1030_Buchmann.evaluation.pdf)
##### Random approach
- Generates field and equation parameters:
- randomly
- using ANSI X9.62 verifiably random method(from seed), until a curve with requested properties appears.
- given input
- Can generate curves repeatedly until one satisfies requested properties:
- `-p / --prime` generates curves until a prime order curve is found.
- `-K / --koblitz` generates a Koblitz curve.
- `-u / --unique` generates a uniquely generated curve (with one generator/cyclic group).
- etc..
##### Invalid curve generation
- Generates *invalid* curves for a given curve.
- These curves have the same field, and *A* parameter in the short Weierstrass equation.
- Multiplication using some(most?) scalar multiplication algorithm proceeds the same way multiplication on the input curve would.
- Used with the `-i / --invalid` option
- [Validation of Elliptic Curve Public Keys - [Antipa, Brown, Menezes, Struik, Vanstone]](https://www.iacr.org/archive/pkc2003/25670211/25670211.pdf)
- [Differential Fault Attacks on Elliptic Curve Cryptosystems - [Biehl, Mayer, Muller]](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.107.3920&rep=rep1&type=pdf)
- [Practical Invalid Curve Attacks on TLS-ECDH - [Jager, Schwenk, Somorovksy]](http://euklid.org/pdf/ECC_Invalid_Curve.pdf)
##### Complex multiplication
- Capable of generating a curve of a given (prime) order.
- Generates a subset of all Elliptic Curves over a given field.
- Used with the `-n / --order` option
- [Constructing elliptic curves of prime order - [Broker, Stevenhagen]](https://arxiv.org/abs/0712.2022)
- [Generating Elliptic Curves of Prime Order - [Savas, Schmidt, Koc]](http://people.oregonstate.edu/~schmidtt/ourPapers/SavasKoc/ches01curve.pdf)
- **Currently not implemented.**
### Build
ecgen can be built using Make or CMake.
#### Make
git clone https://github.com/J08nY/ecgen.git
cd ecgen
git submodule update --init
make
#### CMake
git clone https://github.com/J08nY/ecgen.git
cd ecgen
git submodule update --init
mkdir build && cd build && cmake .. && make
### Requirements
- PARI/GP
- gcc / clang
ecgen uses the [PARI/GP](http://pari.math.u-bordeaux.fr/) library for elliptic
curve arithmetic and it's SEA point counting algorithm implementation. It also requires the
additional [seadata](http://pari.math.u-bordeaux.fr/packages.html) package (seadata and seadata-big recommended for large curves).
ecgen uses some extensions supported by the gcc and clang compilers, namely `__thread`-local storage.
### Libraries
- `lib/parson` *©MIT*
- `lib/sha1` *©MPL / GPLv2 or later*
[parson](https://github.com/kgabis/parson) is used to input and output JSON and is included in the `lib/` directory.
A [SHA-1](lib/sha1/sha1.c) implementation by Paul Kocher, based on the SHA 180-1 Reference Implementation (for ANSI X9.62 algorithm) is used and also included in the `lib/` directory.
### License
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
USA.
*© Eastern Seaboard Phishing Authority*