How to incorporate other ECC curves?

[Ron Aaron]

I'm interested in plugging in other curves, such as Curve25519 and secp256k1, but I can't see any way to do so given the current architecture.  

Any ideas how to approach this?

[Ron Aaron]

Anyone?  I would like to continue to use the tomcrypt framework with newer (or other) ECC curves, just as I can do with regular symmetric ciphers or hashes

[tstde...@gmail.com]

The ideal way is to add the new routines in parallel and then a new PKI api that can talk to them e.g.

int pk_sign_hash(...) that can call ecc_sign_hash or rsa_sign_hash or ...

One issue though is that eddsa signs messages not hashes so the API gets broken so you really need some sort of 

pk_sign_start()

pk_sign_data()

pk_sign_done()

Tom

[Ron Aaron]

Is this something that is on the development schedule?

[Karel Miko]

On Friday, January 15, 2016 at 8:45:39 AM UTC+1, Ron Aaron wrote:

I'm interested in plugging in other curves, such as Curve25519 and secp256k1, but I can't see any way to do so given the current architecture.  

Support for secp256k1 (and others) is already implemented in branch https://github.com/libtom/libtomcrypt/tree/miko-ecc-enhancements - more discussion is here https://github.com/libtom/libtomcrypt/tree/miko-ecc-enhancements

But it is "sleeping" for more than 2 years,

[sebasti...@eciotify.io]

I would be as well interested in an libtomcrypt implementation of secp256k1. Apparently the above links are down. What's the current status of bringing different curves into the API?

[Steffen Jaeckel]

We're still working on that.

https://github.com/libtom/libtomcrypt/tree/pr/ecc-asn1-part contains
support for these curves.

On 10/17/2017 08:50 PM, sebasti...@eciotify.io wrote:
> I would be as well interested in an libtomcrypt implementation of secp256k1. Apparently the above links are down. What's the current status of bringing different curves into the API?
>

--
Steffen Jaeckel - s_ja...@gmx.de
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[Karel Miko]

Just a small correction

* the branch you need is pr/ecc-non-asn1-part

* https://github.com/libtom/libtomcrypt/tree/pr/ecc-non-asn1-part

* corresponding PR https://github.com/libtom/libtomcrypt/pull/236

* please note that API might change before we merge this PR to develop

Usage:

int err;

ecc_key key;

const ltc_ecc_set_type* dp;

unsigned char buf[32];

unsigned long len;

/* generate a new key + export the private key to buf[] */

if ((err = ecc_get_set_by_name("SECP256K1", &dp)) != CRYPT_OK) return err;

if ((err = ecc_make_key_ex(&yarrow_prng, find_prng("yarrow"), &key, dp)) != CRYPT_OK) return err;

len = sizeof(buf);

if ((err = ecc_get_key(buf, &len, PK_PRIVATE, &key)) != CRYPT_OK) return err;

ecc_free(&key);

/* load existing private key from buf[] */

if ((err = ecc_get_set_by_name("SECP256K1", &dp)) != CRYPT_OK) return err;

if ((err = ecc_set_dp(dp, &key)) != CRYPT_OK) return err;

if ((err = ecc_set_key(buf, len, PK_PRIVATE, &key)) != CRYPT_OK) return err;

ecc_free(&key);