Class: Saro::Dat::DatSignature

Inherits:
Object
  • Object
show all
Defined in:
lib/saro/dat/signature.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(algorithm, signing_key, verifying_key, config = nil) ⇒ DatSignature

Returns a new instance of DatSignature.



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# File 'lib/saro/dat/signature.rb', line 40

def initialize(algorithm, signing_key, verifying_key, config = nil)
  @algorithm = algorithm
  @signing_key = signing_key
  @verifying_key = verifying_key
  @config = config || Saro::Dat.get_signature_config(algorithm)
end

Instance Attribute Details

#algorithm ⇒ Object (readonly)

Returns the value of attribute algorithm.



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# File 'lib/saro/dat/signature.rb', line 38

def algorithm
  @algorithm
end

#signing_key ⇒ Object (readonly)

Returns the value of attribute signing_key.



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# File 'lib/saro/dat/signature.rb', line 38

def signing_key
  @signing_key
end

#verifying_key ⇒ Object (readonly)

Returns the value of attribute verifying_key.



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# File 'lib/saro/dat/signature.rb', line 38

def verifying_key
  @verifying_key
end

Class Method Details

.generate(algorithm) ⇒ Object 



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# File 'lib/saro/dat/signature.rb', line 98

def self.generate(algorithm)
  config = Saro::Dat.get_signature_config(algorithm)
  if config[:name] == "HMAC"
    key = OpenSSL::Random.random_bytes(config[:hmac_len])
    new(algorithm, key, key, config)
  else
    key = OpenSSL::PKey::EC.generate(config[:curve])
    begin
      key.check_key
    rescue OpenSSL::PKey::PKeyError, OpenSSL::PKey::ECError => e
      raise Saro::Dat::Error.new(Saro::Dat::ErrorCode::INTERNAL_UNKNOWN, "generated ecdsa key pair is invalid: #{e.message}", cause: e)
    end
    new(algorithm, key, key, config)
  end
end

.imports(algorithm, base64_str) ⇒ Object 



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# File 'lib/saro/dat/signature.rb', line 114

def self.imports(algorithm, base64_str)
  config = Saro::Dat.get_signature_config(algorithm)
  bytes_data = Saro::Dat::Util.decode_base64_url(base64_str)

  if config[:name] == "HMAC"
    if bytes_data.bytesize != config[:hmac_len]
      raise Saro::Dat::Error.new(Saro::Dat::ErrorCode::KEY_INVALID, "hmac key must be #{config[:hmac_len]} bytes, got #{bytes_data.bytesize}")
    end
    new(algorithm, bytes_data, bytes_data, config)
  else
    private_len = config[:private_len]
    public_len = config[:public_len]

    signing_key = nil
    verifying_key = nil

    if bytes_data.bytesize == private_len + public_len
      private_bytes = bytes_data[0, private_len]
      public_bytes = bytes_data[private_len, public_len]
      
      d_value = OpenSSL::BN.new(private_bytes, 2)
      signing_key = create_ec_key(config[:curve], d_value, public_bytes)
      verifying_key = signing_key
    elsif bytes_data.bytesize == public_len
      verifying_key = create_ec_key(config[:curve], nil, bytes_data)
    else
      raise Saro::Dat::Error.new(Saro::Dat::ErrorCode::KEY_INVALID, "ecdsa key length matches neither private+public nor public")
    end

    new(algorithm, signing_key, verifying_key, config)
  end
end

Instance Method Details

#exports(verify_only = false) ⇒ Object 



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# File 'lib/saro/dat/signature.rb', line 147

def exports(verify_only = false)
  if verify_only && !support_verify_only
    raise Saro::Dat::Error.new(Saro::Dat::ErrorCode::KEY_VERIFY_ONLY_UNSUPPORTED, @algorithm.to_s)
  end

  if @config[:name] == "HMAC"
    Saro::Dat::Util.encode_base64_url_str(@verifying_key)
  else
    if verify_only || !@signing_key&.private_key
      public_bytes = @verifying_key.public_key.to_octet_string(:uncompressed)
      Saro::Dat::Util.encode_base64_url_str(public_bytes)
    else
      d_value = @signing_key.private_key
      curve_size = (@signing_key.group.degree + 7) / 8
      d_bytes = d_value.to_s(2).rjust(curve_size, "\x00".b)
      
      public_bytes = @verifying_key.public_key.to_octet_string(:uncompressed)
      Saro::Dat::Util.encode_base64_url_str(d_bytes + public_bytes)
    end
  end
end

#pair ⇒ Object 



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# File 'lib/saro/dat/signature.rb', line 242

def pair
  @config[:name] == "ECDSA"
end

#sign(body) ⇒ Object

Raises:



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# File 'lib/saro/dat/signature.rb', line 169

def sign(body)
  raise Saro::Dat::Error.new(Saro::Dat::ErrorCode::SIG_KEY_MISSING, "this key is verify-only") unless @signing_key
  body = normalize_body(body)
  raise Saro::Dat::Error.new(Saro::Dat::ErrorCode::CONFIG_ARGUMENT_INVALID, "body to sign is empty") if body.nil? || body.empty?

  if @config[:name] == "HMAC"
    OpenSSL::HMAC.digest(@config[:hash], @signing_key, body)
  else
    signature_der = @signing_key.dsa_sign_asn1(OpenSSL::Digest.digest(@config[:hash], body))
    der_to_raw_signature(signature_der)
  end
end

#signable ⇒ Object 



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# File 'lib/saro/dat/signature.rb', line 238

def signable
  !@signing_key.nil?
end

#support_verify_only ⇒ Object 



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# File 'lib/saro/dat/signature.rb', line 246

def support_verify_only
  @config[:name] == "ECDSA"
end

#verify(body, signature) ⇒ Object

Verifies a raw (already decoded) signature. Use #verify_base64 for a base64url-encoded signature: the branch used to be picked from the string's encoding tag, so a raw signature that merely carried a UTF-8 tag was silently run through the base64 decoder.



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# File 'lib/saro/dat/signature.rb', line 186

def verify(body, signature)
  verify_bytes(body, signature)
end

#verify_base64(body, signature_base64) ⇒ Object

Verifies a base64url-encoded signature.



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# File 'lib/saro/dat/signature.rb', line 191

def verify_base64(body, signature_base64)
  sig_bytes = begin
    Saro::Dat::Util.decode_base64_url(signature_base64)
  rescue Saro::Dat::Error => e
    raise Saro::Dat::Error.new(Saro::Dat::ErrorCode::SIG_MALFORMED, "signature is not base64url", cause: e)
  end
  verify_bytes(body, sig_bytes)
end