Method: ECIES::Crypt#encrypt

Defined in:
lib/ecies/crypt.rb

#encrypt(key, message) ⇒ String

Encrypts a message to a public key using ECIES.

Parameters:

  • key (OpenSSL::EC:PKey) —

    The public key.

  • message (String) —

    The plain-text message.

Returns:

  • (String) —

    The octet string of the encrypted message.

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# File 'lib/ecies/crypt.rb', line 59

def encrypt(key, message)
  key.public_key? or raise "Must have public key to encrypt"
  @cipher.reset

  ephemeral_key = OpenSSL::PKey::EC.generate(key.group)
  ephemeral_public_key_octet = ephemeral_key.public_key.to_octet_string(:compressed)

  shared_secret = ephemeral_key.dh_compute_key(key.public_key)

  key_pair = kdf(shared_secret, @cipher.key_len + @mac_length, ephemeral_public_key_octet)
  cipher_key = key_pair.byteslice(0, @cipher.key_len)
  hmac_key = key_pair.byteslice(-@mac_length, @mac_length)

  @cipher.encrypt
  @cipher.iv = IV
  @cipher.key = cipher_key
  ciphertext = @cipher.update(message) + @cipher.final

  mac = OpenSSL::HMAC.digest(@mac_digest, hmac_key, ciphertext + @mac_shared_info).byteslice(0, @mac_length)

  ephemeral_public_key_octet + ciphertext + mac
end