Class: RbNaCl::SimpleBox
- Inherits:
-
Object
- Object
- RbNaCl::SimpleBox
- Extended by:
- Forwardable
- Defined in:
- lib/rbnacl/simple_box.rb
Overview
The simplest nonce strategy that could possibly work
This class implements the simplest possible nonce generation strategy to wrap a RbNaCl::Box or RbNaCl::SecretBox. A 24-byte random nonce is used for the encryption and is prepended to the message. When it is time to open the box, the message is split into nonce and ciphertext, and then the box is decrypted.
Thanks to the size of the nonce, the chance of a collision is negligible. For example, after encrypting 2^64 messages, the odds of their having been repeated nonce is approximately 2^-64. As an additional convenience, the ciphertexts may be encoded or decoded by any of the encoders implemented in the library.
The resulting ciphertexts are 40 bytes longer than the plain text (24 byte nonce plus a 16 byte authenticator). This might be annoying if you're encrypting tweets, but for files represents a fairly small overhead.
Some caveats:
- If your random source is broken, so is the security of the messages. You have bigger problems than just this library at that point, but it's worth saying.
- The confidentiality of your messages is assured with this strategy, but there is no protection against messages being reordered and replayed by an active adversary.
Class Method Summary collapse
-
.from_keypair(public_key, private_key) ⇒ RandomNonceBox
Use a pair of keys to create a RandomNonceBox.
-
.from_secret_key(secret_key) ⇒ RandomNonceBox
Use a secret key to create a RandomNonceBox.
Instance Method Summary collapse
-
#box(message) ⇒ String
(also: #encrypt)
Encrypts the message with a random nonce.
-
#initialize(box) ⇒ RandomNonceBox
constructor
Create a new RandomNonceBox.
-
#open(enciphered_message) ⇒ String
(also: #decrypt)
Decrypts the ciphertext with a random nonce.
Constructor Details
#initialize(box) ⇒ RandomNonceBox
Create a new RandomNonceBox
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# File 'lib/rbnacl/simple_box.rb', line 39 def initialize(box) @box = box end |
Class Method Details
.from_keypair(public_key, private_key) ⇒ RandomNonceBox
Use a pair of keys to create a RandomNonceBox
This is a convenience method. It takes a pair of keys and instantiates a Box under the hood, then returns the new RandomNonceBox.
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# File 'lib/rbnacl/simple_box.rb', line 64 def self.from_keypair(public_key, private_key) new(Box.new(public_key, private_key)) end |
.from_secret_key(secret_key) ⇒ RandomNonceBox
Use a secret key to create a RandomNonceBox
This is a convenience method. It takes a secret key and instantiates a SecretBox under the hood, then returns the new RandomNonceBox.
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# File 'lib/rbnacl/simple_box.rb', line 51 def self.from_secret_key(secret_key) new(SecretBox.new(secret_key)) end |
Instance Method Details
#box(message) ⇒ String Also known as: encrypt
Encrypts the message with a random nonce
Encrypts the message with a random nonce, then returns the ciphertext with the nonce prepended. Optionally encodes the message using an encoder.
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# File 'lib/rbnacl/simple_box.rb', line 76 def box() nonce = generate_nonce cipher_text = @box.box(nonce, ) nonce + cipher_text end |
#open(enciphered_message) ⇒ String Also known as: decrypt
Decrypts the ciphertext with a random nonce
Takes a ciphertext, optionally decodes it, then splits the nonce off the front and uses this to decrypt. Returns the message.
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# File 'lib/rbnacl/simple_box.rb', line 93 def open() nonce, ciphertext = extract_nonce(.to_s) @box.open(nonce, ciphertext) end |