Class: RbNaCl::Signatures::Ed25519::SigningKey

Inherits:
Object
  • Object
show all
Extended by:
RbNaCl::Sodium
Includes:
KeyComparator, RbNaCl::Serializable
Defined in:
lib/rbnacl/signatures/ed25519/signing_key.rb

Overview

Private key for producing digital signatures using the Ed25519 algorithm. Ed25519 provides a 128-bit security level, that is to say, all known attacks take at least 2^128 operations, providing the same security level as AES-128, NIST P-256, and RSA-3072.

Signing keys are produced from a 32-byte (256-bit) random seed value. This value can be passed into the SigningKey constructor as a String whose bytesize is 32.

The public VerifyKey can be computed from the private 32-byte seed value as well, eliminating the need to store a "keypair".

SigningKey produces 64-byte (512-bit) signatures. The signatures are deterministic: signing the same message will always produce the same signature. This prevents "entropy failure" seen in other signature algorithms like DSA and ECDSA, where poor random number generators can leak enough information to recover the private key.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from RbNaCl::Sodium

sodium_constant, sodium_function, sodium_primitive, sodium_type

Methods included from RbNaCl::Serializable

#inspect, #to_s, #to_str

Methods included from KeyComparator

#<=>, #==

Constructor Details

#initialize(seed) ⇒ RbNaCl::SigningKey

Create a SigningKey from a seed value

Parameters:

  • seed (String) —

    Random 32-byte value (i.e. private key)



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# File 'lib/rbnacl/signatures/ed25519/signing_key.rb', line 53

def initialize(seed)
  seed = seed.to_s

  Util.check_length(seed, Ed25519::SEEDBYTES, "seed")

  pk = Util.zeros(Ed25519::VERIFYKEYBYTES)
  sk = Util.zeros(Ed25519::SIGNINGKEYBYTES)

  self.class.sign_ed25519_seed_keypair(pk, sk, seed) || raise(CryptoError, "Failed to generate a key pair")

  @seed, @signing_key = seed, sk
  @verify_key = VerifyKey.new(pk)
end

Instance Attribute Details

#verify_key ⇒ Object (readonly)

Returns the value of attribute verify_key.



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# File 'lib/rbnacl/signatures/ed25519/signing_key.rb', line 39

def verify_key
  @verify_key
end

Class Method Details

.generate ⇒ RbNaCl::SigningKey

Generate a random SigningKey

Returns:



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# File 'lib/rbnacl/signatures/ed25519/signing_key.rb', line 44

def self.generate
  new RbNaCl::Random.random_bytes(Ed25519::SEEDBYTES)
end

.signature_bytes ⇒ Integer

The size of signatures generated by the SigningKey class

Returns:

  • (Integer) —

    The number of bytes in a signature



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# File 'lib/rbnacl/signatures/ed25519/signing_key.rb', line 94

def self.signature_bytes; Ed25519::SIGNATUREBYTES; end

Instance Method Details

#primitive ⇒ Symbol

The crypto primitive this SigningKey class uses for signatures

Returns:

  • (Symbol) —

    The primitive



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# File 'lib/rbnacl/signatures/ed25519/signing_key.rb', line 89

def primitive; self.class.primitive; end

#sign(message) ⇒ String

Sign a message using this key

Parameters:

  • message (String) —

    Message to be signed by this key

Returns:

  • (String) —

    Signature as bytes



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# File 'lib/rbnacl/signatures/ed25519/signing_key.rb', line 72

def sign(message)
  buffer = Util.prepend_zeros(signature_bytes, message)
  buffer_len = Util.zeros(FFI::Type::LONG_LONG.size)

  self.class.sign_ed25519(buffer, buffer_len, message, message.bytesize, @signing_key)

  buffer[0, signature_bytes]
end

#signature_bytes ⇒ Integer

The size of signatures generated by the SigningKey instance

Returns:

  • (Integer) —

    The number of bytes in a signature



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# File 'lib/rbnacl/signatures/ed25519/signing_key.rb', line 99

def signature_bytes; Ed25519::SIGNATUREBYTES; end

#to_bytes ⇒ String

Return the raw seed value of this key

Returns:

  • (String) —

    seed used to create this key



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# File 'lib/rbnacl/signatures/ed25519/signing_key.rb', line 84

def to_bytes; @seed; end