Class: JWT::PQ::Algorithms::HybridEdDsa

Inherits:
Object
  • Object
show all
Includes:
JWA::SigningAlgorithm
Defined in:
lib/jwt/pq/algorithms/hybrid_eddsa.rb

Overview

JWT signing algorithm for hybrid EdDSA + ML-DSA signatures.

The signature is a simple concatenation: ed25519_sig (64 bytes) || ml_dsa_sig. This allows PQ-aware verifiers to validate both, while the fixed 64-byte Ed25519 prefix makes it possible to split the signatures deterministically.

Constant Summary collapse

ED25519_SIG_SIZE = 
64

Instance Method Summary collapse

Constructor Details

#initialize(alg) ⇒ HybridEdDsa

Returns a new instance of HybridEdDsa.



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# File 'lib/jwt/pq/algorithms/hybrid_eddsa.rb', line 18

def initialize(alg)
  @alg = alg
  @ml_dsa_algorithm = alg.sub("EdDSA+", "")
  @header = { "alg" => alg, "pq_alg" => @ml_dsa_algorithm }.freeze
end

Instance Method Details

#header ⇒ Object 



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# File 'lib/jwt/pq/algorithms/hybrid_eddsa.rb', line 24

def header(*)
  @header
end

#sign(data:, signing_key:) ⇒ Object 



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# File 'lib/jwt/pq/algorithms/hybrid_eddsa.rb', line 28

def sign(data:, signing_key:)
  unless signing_key.is_a?(JWT::PQ::HybridKey)
    raise_sign_error!(
      "Expected a JWT::PQ::HybridKey, got #{signing_key.class}. " \
      "Use JWT::PQ::HybridKey.generate to create a hybrid key."
    )
  end
  raise_sign_error!("Both Ed25519 and ML-DSA private keys required") unless signing_key.private?

  ed_sig = signing_key.ed25519_signing_key.sign(data)
  ml_sig = signing_key.ml_dsa_key.sign(data)

  # Concatenate: Ed25519 (64 bytes) || ML-DSA (variable)
  ed_sig + ml_sig
end

#verify(data:, signature:, verification_key:) ⇒ Object 



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# File 'lib/jwt/pq/algorithms/hybrid_eddsa.rb', line 44

def verify(data:, signature:, verification_key:)
  unless verification_key.is_a?(JWT::PQ::HybridKey)
    raise_verify_error!(
      "Expected a JWT::PQ::HybridKey, got #{verification_key.class}."
    )
  end

  return false if signature.bytesize <= ED25519_SIG_SIZE

  ed_sig = signature.byteslice(0, ED25519_SIG_SIZE)
  ml_sig = signature.byteslice(ED25519_SIG_SIZE..)

  ed_valid = begin
    verification_key.ed25519_verify_key.verify(ed_sig, data)
    true
  rescue Ed25519::VerifyError
    false
  end

  ml_valid = verification_key.ml_dsa_key.verify(data, ml_sig)

  ed_valid && ml_valid
rescue JWT::PQ::Error
  false
end