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Chalsa: Provide ::Random interface

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Didactic Drunk 2022-05-12 13:18:17 -07:00
parent 2893c5525d
commit e350f5ad4b
1 changed files with 21 additions and 11 deletions
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32
src/sodium/cipher/chalsa.cr
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@ -6,6 +6,8 @@ module Sodium::Cipher
# #
# What? They're both dance? # What? They're both dance?
abstract class Chalsa abstract class Chalsa
include Random
getter key : Crypto::Secret getter key : Crypto::Secret
getter! nonce : Bytes? getter! nonce : Bytes?
@ -42,7 +44,7 @@ module Sodium::Cipher
end end
def random_nonce def random_nonce
self.nonce = Random::Secure.random_bytes nonce_size self.nonce = ::Random::Secure.random_bytes nonce_size
end end
# Xor's src with the cipher output and returns a new Slice # Xor's src with the cipher output and returns a new Slice
@ -60,17 +62,14 @@ module Sodium::Cipher
# Use as a CSPRNG. # Use as a CSPRNG.
def random_bytes(bytes : Bytes) : Bytes def random_bytes(bytes : Bytes) : Bytes
# TODO: Switch to memset
Sodium.memzero bytes
update bytes, bytes update bytes, bytes
bytes bytes
end end
# Use as a CSPRNG. def next_u : UInt8
def random_bytes(size : Int) : Bytes buf = uninitialized UInt8[1]
bytes = Bytes.new size random_bytes buf.to_slice
update bytes, bytes buf.unsafe_as(UInt8)
bytes
end end
# Always returns false. Sadness... # Always returns false. Sadness...
@ -90,11 +89,22 @@ module Sodium::Cipher
{% for key, val in {"XSalsa20" => "xsalsa20", "Salsa20" => "salsa20", "XChaCha20" => "xchacha20", "ChaCha20Ietf" => "chacha20_ietf", "ChaCha20" => "chacha20"} %} {% for key, val in {"XSalsa20" => "xsalsa20", "Salsa20" => "salsa20", "XChaCha20" => "xchacha20", "ChaCha20Ietf" => "chacha20_ietf", "ChaCha20" => "chacha20"} %}
# These classes can be used to generate pseudo-random data from a key, # These classes can be used to generate pseudo-random data from a key,
# or as building blocks for implementing custom constructions, but they # or as building blocks for implementing custom constructions, but they
# are not alternatives to secretbox. # are not alternatives to `SecretBox`.
# #
# See [https://libsodium.gitbook.io/doc/advanced/stream_ciphers](https://libsodium.gitbook.io/doc/advanced/stream_ciphers) for further information. # See [https://libsodium.gitbook.io/doc/advanced/stream_ciphers](https://libsodium.gitbook.io/doc/advanced/stream_ciphers) for further information.
# #
# This class mimicks the OpenSSL::Cipher interface with minor differences. # This class mimicks the `OpenSSL::Cipher` interface with minor differences.
#
# Also provides a `::Random` interface.
# * Lacks forward secrecy.
# * ~3x faster than `::Random::Secure`
#
# Use with caution. When in doubt use `::Random::Secure`
#
# Possibly safe uses:
# * Test data
# * Overwriting storage with random data
# * Single player video games (maybe)
# #
# See `spec/sodium/cipher/chalsa_spec.cr` for examples on how to use this class. # See `spec/sodium/cipher/chalsa_spec.cr` for examples on how to use this class.
# #
@ -104,7 +114,7 @@ module Sodium::Cipher
NONCE_SIZE = LibSodium.crypto_stream_{{ val.id }}_noncebytes.to_i32 NONCE_SIZE = LibSodium.crypto_stream_{{ val.id }}_noncebytes.to_i32
def self.random def self.random
new key: Sodium::SecureBuffer.random(KEY_SIZE), nonce: Random::Secure.random_bytes(NONCE_SIZE) new key: Sodium::SecureBuffer.random(KEY_SIZE), nonce: ::Random::Secure.random_bytes(NONCE_SIZE)
end end
# Xor's src with the cipher output and places in dst. # Xor's src with the cipher output and places in dst.