/
ecdsa.rb
76 lines (66 loc) · 2.5 KB
/
ecdsa.rb
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# frozen_string_literal: true
module JWT
module JWA
module Ecdsa
module_function
NAMED_CURVES = {
'prime256v1' => {
algorithm: 'ES256',
digest: 'sha256'
},
'secp256r1' => { # alias for prime256v1
algorithm: 'ES256',
digest: 'sha256'
},
'secp384r1' => {
algorithm: 'ES384',
digest: 'sha384'
},
'secp521r1' => {
algorithm: 'ES512',
digest: 'sha512'
},
'secp256k1' => {
algorithm: 'ES256K',
digest: 'sha256'
}
}.freeze
SUPPORTED = NAMED_CURVES.map { |_, c| c[:algorithm] }.uniq.freeze
def sign(algorithm, msg, key)
curve_definition = curve_by_name(key.group.curve_name)
key_algorithm = curve_definition[:algorithm]
if algorithm != key_algorithm
raise IncorrectAlgorithm, "payload algorithm is #{algorithm} but #{key_algorithm} signing key was provided"
end
digest = OpenSSL::Digest.new(curve_definition[:digest])
asn1_to_raw(key.dsa_sign_asn1(digest.digest(msg)), key)
end
def verify(algorithm, public_key, signing_input, signature)
curve_definition = curve_by_name(public_key.group.curve_name)
key_algorithm = curve_definition[:algorithm]
if algorithm != key_algorithm
raise IncorrectAlgorithm, "payload algorithm is #{algorithm} but #{key_algorithm} verification key was provided"
end
digest = OpenSSL::Digest.new(curve_definition[:digest])
public_key.dsa_verify_asn1(digest.digest(signing_input), raw_to_asn1(signature, public_key))
rescue OpenSSL::PKey::PKeyError
raise JWT::VerificationError, 'Signature verification raised'
end
def curve_by_name(name)
NAMED_CURVES.fetch(name) do
raise UnsupportedEcdsaCurve, "The ECDSA curve '#{name}' is not supported"
end
end
def raw_to_asn1(signature, private_key)
byte_size = (private_key.group.degree + 7) / 8
sig_bytes = signature[0..(byte_size - 1)]
sig_char = signature[byte_size..-1] || ''
OpenSSL::ASN1::Sequence.new([sig_bytes, sig_char].map { |int| OpenSSL::ASN1::Integer.new(OpenSSL::BN.new(int, 2)) }).to_der
end
def asn1_to_raw(signature, public_key)
byte_size = (public_key.group.degree + 7) / 8
OpenSSL::ASN1.decode(signature).value.map { |value| value.value.to_s(2).rjust(byte_size, "\x00") }.join
end
end
end
end