class SSHKey

# File lib/sshkey.rb, line 27
def generate(options = {})
  type   = options[:type] || "rsa"

  # JRuby modulus size must range from 512 to 1024
  default_bits = type == "rsa" ? 2048 : 1024

  bits   = options[:bits] || default_bits
  cipher = OpenSSL::Cipher::Cipher.new("AES-128-CBC") if options[:passphrase]

  case type.downcase
  when "rsa" then new(OpenSSL::PKey::RSA.generate(bits).to_pem(cipher, options[:passphrase]), options)
  when "dsa" then new(OpenSSL::PKey::DSA.generate(bits).to_pem(cipher, options[:passphrase]), options)
  else
    raise "Unknown key type: #{type}"
  end
end

# File lib/sshkey.rb, line 74
def md5_fingerprint(key)
  if key.match(/PRIVATE/)
    new(key).md5_fingerprint
  else
    Digest::MD5.hexdigest(decoded_key(key)).gsub(fingerprint_regex, '\1:\2')
  end
end

# File lib/sshkey.rb, line 184
def initialize(private_key, options = {})
  @passphrase = options[:passphrase]
  @comment    = options[:comment] || ""
  self.directives = options[:directives] || []
  begin
    @key_object = OpenSSL::PKey::RSA.new(private_key, passphrase)
    @type = "rsa"
  rescue
    @key_object = OpenSSL::PKey::DSA.new(private_key, passphrase)
    @type = "dsa"
  end
end

# File lib/sshkey.rb, line 84
def sha1_fingerprint(key)
  if key.match(/PRIVATE/)
    new(key).sha1_fingerprint
  else
    Digest::SHA1.hexdigest(decoded_key(key)).gsub(fingerprint_regex, '\1:\2')
  end
end

# File lib/sshkey.rb, line 65
def ssh_public_key_bits(ssh_public_key)
  unpacked_byte_array( *parse_ssh_public_key(ssh_public_key) ).last.num_bytes * 8
end

# File lib/sshkey.rb, line 98
def ssh_public_key_to_ssh2_public_key(ssh_public_key, headers = nil)
  raise PublicKeyError, "invalid ssh public key" unless SSHKey.valid_ssh_public_key?(ssh_public_key)

  source_format, source_key = parse_ssh_public_key(ssh_public_key)

  # Add a 'Comment' Header Field unless others are explicitly passed in
  if source_comment = ssh_public_key.split(source_key)[1]
    headers = {'Comment' => source_comment.strip} if headers.nil? && !source_comment.empty?
  end
  header_fields = build_ssh2_headers(headers)

  ssh2_key = "---- BEGIN SSH2 PUBLIC KEY ----\n"
  ssh2_key << header_fields unless header_fields.nil?
  ssh2_key << source_key.scan(/.{1,#{SSH2_LINE_LENGTH}}/).join("\n")
  ssh2_key << "\n---- END SSH2 PUBLIC KEY ----"
end

# File lib/sshkey.rb, line 51
def valid_ssh_public_key?(ssh_public_key)
  ssh_type, encoded_key = parse_ssh_public_key(ssh_public_key)
  SSH_CONVERSION[SSH_TYPES.invert[ssh_type]].size == unpacked_byte_array(ssh_type, encoded_key).size
rescue
  false
end

# File lib/sshkey.rb, line 157
def build_ssh2_headers(headers = {})
  return nil if headers.nil? || headers.empty?

  headers.keys.sort.collect do |header_tag|
    # header-tag must be us-ascii & <= 64 bytes and header-data must be UTF-8 & <= 1024 bytes
    raise PublicKeyError, "SSH2 header-tag '#{header_tag}' must be US-ASCII" unless header_tag.each_byte.all? {|b| b < 128 }
    raise PublicKeyError, "SSH2 header-tag '#{header_tag}' must be <= 64 bytes" unless header_tag.size <= 64
    raise PublicKeyError, "SSH2 header-value for '#{header_tag}' must be <= 1024 bytes" unless headers[header_tag].size <= 1024

    header_field = "#{header_tag}: #{headers[header_tag]}"
    header_field.scan(/.{1,#{SSH2_LINE_LENGTH}}/).join("\\\n")
  end.join("\n") << "\n"
end

# File lib/sshkey.rb, line 139
def decoded_key(key)
  Base64.decode64(parse_ssh_public_key(key).last)
end

# File lib/sshkey.rb, line 143
def fingerprint_regex
  /(.{2})(?=.)/
end

# File lib/sshkey.rb, line 147
def parse_ssh_public_key(public_key)
  raise PublicKeyError, "newlines are not permitted between key data" if public_key =~ /\n(?!$)/

  parsed = public_key.split(" ")
  parsed.each_with_index do |el, index|
    return parsed[index..(index+1)] if SSH_TYPES.invert[el]
  end
  raise PublicKeyError, "cannot determine key type"
end

# File lib/sshkey.rb, line 117
def unpacked_byte_array(ssh_type, encoded_key)
  prefix = [7].pack("N") + ssh_type
  decoded = Base64.decode64(encoded_key)

  # Base64 decoding is too permissive, so we should validate if encoding is correct
  unless Base64.encode64(decoded).gsub("\n", "") == encoded_key && decoded.slice!(0, prefix.length) == prefix
    raise PublicKeyError, "validation error"
  end

  data = []
  until decoded.empty?
    front = decoded.slice!(0,4)
    size = front.unpack("N").first
    segment = decoded.slice!(0, size)
    unless front.length == 4 && segment.length == size
      raise PublicKeyError, "byte array too short"
    end
    data << OpenSSL::BN.new(segment, 2)
  end
  return data
end

# File lib/sshkey.rb, line 255
def bits
  self.class.ssh_public_key_bits(ssh_public_key)
end

# File lib/sshkey.rb, line 316
def directives=(directives)
  @directives = Array[directives].flatten.compact
end

# File lib/sshkey.rb, line 209
def encrypted_private_key
  return private_key unless passphrase
  key_object.to_pem(OpenSSL::Cipher::Cipher.new("AES-128-CBC"), passphrase)
end

# File lib/sshkey.rb, line 244
def md5_fingerprint
  Digest::MD5.hexdigest(ssh_public_key_conversion).gsub(/(.{2})(?=.)/, '\1:\2')
end

# File lib/sshkey.rb, line 200
def private_key
  key_object.to_pem
end

# File lib/sshkey.rb, line 217
def public_key
  key_object.public_key.to_pem
end

# File lib/sshkey.rb, line 276
def randomart
  fieldsize_x = 17
  fieldsize_y = 9
  x = fieldsize_x / 2
  y = fieldsize_y / 2
  raw_digest = Digest::MD5.digest(ssh_public_key_conversion)
  num_bytes = raw_digest.bytesize

  field = Array.new(fieldsize_x) { Array.new(fieldsize_y) {0} }

  raw_digest.bytes.each do |byte|
    4.times do
      x += (byte & 0x1 != 0) ? 1 : -1
      y += (byte & 0x2 != 0) ? 1 : -1

      x = [[x, 0].max, fieldsize_x - 1].min
      y = [[y, 0].max, fieldsize_y - 1].min

      field[x][y] += 1 if (field[x][y] < num_bytes - 2)

      byte >>= 2
    end
  end

  field[fieldsize_x / 2][fieldsize_y / 2] = num_bytes - 1
  field[x][y] = num_bytes
  augmentation_string = " .o+=*BOX@%&#/^SE"
  output = "+--#{sprintf("[%4s %4u]", type.upcase, bits)}----+\n"
  fieldsize_y.times do |y|
    output << "|"
    fieldsize_x.times do |x|
      output << augmentation_string[[field[x][y], num_bytes].min]
    end
    output << "|"
    output << "\n"
  end
  output << "+#{"-" * fieldsize_x}+"
  output
end

# File lib/sshkey.rb, line 250
def sha1_fingerprint
  Digest::SHA1.hexdigest(ssh_public_key_conversion).gsub(/(.{2})(?=.)/, '\1:\2')
end

# File lib/sshkey.rb, line 237
def ssh2_public_key(headers = nil)
  self.class.ssh_public_key_to_ssh2_public_key(ssh_public_key, headers)
end

# File lib/sshkey.rb, line 224
def ssh_public_key
  [directives.join(",").strip, SSH_TYPES[type], Base64.encode64(ssh_public_key_conversion).gsub("\n", ""), comment].join(" ").strip
end

# File lib/sshkey.rb, line 332
def ssh_public_key_conversion
  typestr = SSH_TYPES[type]
  methods = SSH_CONVERSION[type]
  pubkey = key_object.public_key
  methods.inject([7].pack("N") + typestr) do |pubkeystr, m|
    # Given pubkey.class == OpenSSL::BN, pubkey.to_s(0) returns an MPI
    # formatted string (length prefixed bytes). This is not supported by
    # JRuby, so we still have to deal with length and data separately.
    val = pubkey.send(m)

    # Get byte-representation of absolute value of val
    data = val.to_s(2)

    first_byte = data[0,1].unpack("c").first
    if val < 0
      # For negative values, highest bit must be set
      data[0] = [0x80 & first_byte].pack("c")
    elsif first_byte < 0
      # For positive values where highest bit would be set, prefix with \0
      data = "\0" + data
    end
    pubkeystr + [data.length].pack("N") + data
  end
end