Unknown cipher when encrypting data

Erlang & BEAM Forum (archived) Questions / Help (archived)
,
18

Just in case, if any one is looking for a complete (encryption and decryption) working example. with new API

The new (OTP> 23) API is used.
Please see the below link for detailed documenation.
Erlang -- crypto

defmodule Aes do
  @aad "AES256GCM"
  require Logger

    def encrypt(text_to_encrypt \\ "5123456789012346") do
      Logger.info("Entering encrypt function")
      Logger.info("Encryption -  Text to Encrypt #{text_to_encrypt}")
      dek = :crypto.strong_rand_bytes(32)
      iv = :crypto.strong_rand_bytes(32)

      case :crypto.crypto_one_time_aead(:aes_256_gcm, dek, iv, text_to_encrypt, @aad, true) do
        {ciphertext, ciphertag} ->
          Base.encode64(iv <> ciphertag <> ciphertext)
          Logger.info("Encryption - DEK (Data Encryption Key) in Base64 #{Base.encode64(dek)}")
          Logger.info("Encryption - IV (Intialization Vector) in Base64 #{Base.encode64(iv)}")
          Logger.info("Encryption - Encrypted text value in Base64 #{Base.encode64(iv <> ciphertag <> ciphertext)}")
          decrypt(iv <> ciphertag <> ciphertext, dek)
        _ ->
         Logger.info("Error in crypto.crypto_one_time_aead")
        end
    end


  def decrypt(encrypted_text, dek) do
    Logger.info("Entering decypt function")
    <<iv::binary-32, ciphertag::binary-16, ciphertext::binary>> = encrypted_text
    Logger.info("Decryption - DEK (Data Encryption Key) in Base64 #{Base.encode64(dek)}")
    Logger.info("Decryption - IV (Intialization Vector) in Base64 #{Base.encode64(iv)}")
    Logger.info("Decryption - CipherTag in Base64 #{Base.encode64(ciphertag)}")
    Logger.info("Decryption - CipherText in Base64 #{Base.encode64(ciphertext)}")
    Logger.info("Decryption - Decrypted text #{:crypto.crypto_one_time_aead(:aes_256_gcm, dek,iv, ciphertext, @aad, ciphertag, false)}")
    :crypto.crypto_one_time_aead(:aes_256_gcm, dek,iv, ciphertext, @aad, ciphertag, false)
  end

end

If you would like to learn how this all works together, please visit the below excellent url. (This uses the old API, be careful). It gives detailed understanding of whats under the hood).

4 Likes