This is a Ruby implementation of the Hash to Curves proposed by the IETF.

It has been tested using the Test Vector provided, but the code has not been audited to ensure functional specification and safety. Also It is under development and is subject to change without backward compatibility.

The following cipher suites are currently supported:

• secp256k1_XMD:SHA-256_SSWU_NU_
• secp256k1_XMD:SHA-256_SSWU_RO_
• BLS12381G1_XMD:SHA-256_SSWU_NU_
• BLS12381G1_XMD:SHA-256_SSWU_RO_
• P256_XMD:SHA-256_SSWU_NU_
• P256_XMD:SHA-256_SSWU_RO_
• P384_XMD:SHA-384_SSWU_NU_
• P384_XMD:SHA-384_SSWU_RO_
• P521_XMD:SHA-512_SSWU_NU_
• P521_XMD:SHA-512_SSWU_RO_

Add this line to your application's Gemfile:

gem 'h2c'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install h2c

require 'h2c'

dst = "QUUX-V01-CS02-with-secp256k1_XMD:SHA-256_SSWU_RO_"

h2c = H2C.get(H2C::Suite::SECP256K1_XMDSHA256_SSWU_RO_, dst)

msg = "abc"

result = h2c.digest(msg)
puts result.inspect
#<ECDSA::Point: secp256k1, 0x3377e01eab42db296b512293120c6cee72b6ecf9f9205760bd9ff11fb3cb2c4b, 0x7f95890f33efebd1044d382a01b1bee0900fb6116f94688d487c6c7b9c8371f6>