Module: RbNaCl::Util

Extended by:
Sodium
Defined in:
lib/rbnacl/util.rb

Overview

Various utility functions

Class Method Summary collapse

Methods included from Sodium

primitive, sodium_constant, sodium_function, sodium_function_with_return_code, sodium_primitive, sodium_type

Class Method Details

.bin2hex(bytes) ⇒ String

Hex encodes a message

Parameters:

  • bytes (String) —

    The bytes to encode

Returns:

  • (String) —

    Tasty, tasty hexadecimal



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# File 'lib/rbnacl/util.rb', line 193

def bin2hex(bytes)
  bytes.to_s.unpack("H*").first
end

.check_length(string, length, description) ⇒ Object

Check the length of the passed in string

In several places through the codebase we have to be VERY strict with what length of string we accept. This method supports that.

Parameters:

  • string (String) —

    The string to compare

  • length (Integer) —

    The desired length

  • description (String) —

    Description of the string (used in the error)

Raises:



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# File 'lib/rbnacl/util.rb', line 82

def check_length(string, length, description)
  if string.nil?
    raise LengthError,
          "#{description} was nil (Expected #{length.to_int})",
          caller
  end

  if string.bytesize != length.to_int
    raise LengthError,
          "#{description} was #{string.bytesize} bytes (Expected #{length.to_int})",
          caller
  end
  true
end

.check_string(string, length, description) ⇒ Object

Check a passed in string, converting the argument if necessary

In several places through the codebase we have to be VERY strict with the strings we accept. This method supports that.

Parameters:

  • string (#to_str) —

    The input string

  • length (Integer) —

    The only acceptable length of the string

  • description (String) —

    Description of the string (used in the error)

Raises:

  • (ArgumentError) —

    If we cannot convert to a string with #to_str

  • (RbNaCl::LengthError) —

    If the string is not the right length



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# File 'lib/rbnacl/util.rb', line 108

def check_string(string, length, description)
  unless string.respond_to? :to_str
    raise TypeError, "can't convert #{string.class} into String with #to_str"
  end

  string = string.to_str
  unless string.encoding == Encoding::BINARY
    raise EncodingError, "strings must use BINARY encoding (got #{string.encoding})"
  end
  check_length(string, length, description)

  string
end

.hex2bin(hex) ⇒ String

Hex decodes a message

Parameters:

  • hex (String) —

    hex to decode.

Returns:

  • (String) —

    crisp and clean bytes



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# File 'lib/rbnacl/util.rb', line 202

def hex2bin(hex)
  [hex.to_s].pack("H*")
end

.prepend_zeros(n, message) ⇒ String

Prepends a message with zeros

Many functions require a string with some zeros prepended.

Parameters:

  • n (Integer) —

    The number of zeros to prepend

  • message (String) —

    The string to be prepended

Returns:

  • (String) —

    a bunch of zeros



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# File 'lib/rbnacl/util.rb', line 36

def prepend_zeros(n, message)
  zeros(n) + message
end

.remove_zeros(n, message) ⇒ String

Remove zeros from the start of a message

Many functions require a string with some zeros prepended, then need them removing after. Note: this modifies the passed in string

Parameters:

  • n (Integer) —

    The number of zeros to remove

  • message (String) —

    The string to be slice

Returns:

  • (String) —

    less a bunch of zeros



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# File 'lib/rbnacl/util.rb', line 49

def remove_zeros(n, message)
  message.slice!(n, message.bytesize - n)
end

.verify16(one, two) ⇒ Boolean

Compare two 16 byte strings in constant time

This should help to avoid timing attacks for string comparisons in your application. Note that many of the functions (such as OneTime#verify) use this method under the hood already.

Parameters:

  • one (String) —

    String #1

  • two (String) —

    String #2

Returns:

  • (Boolean) —

    Well, are they equal?



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# File 'lib/rbnacl/util.rb', line 165

def verify16(one, two)
  return false unless two.bytesize == 16 && one.bytesize == 16
  c_verify16(one, two)
end

.verify16!(one, two) ⇒ Boolean

Compare two 16 byte strings in constant time

This should help to avoid timing attacks for string comparisons in your application. Note that many of the functions (such as OneTime#verify) use this method under the hood already.

Parameters:

  • one (String) —

    String #1

  • two (String) —

    String #2

Returns:

  • (Boolean) —

    Well, are they equal?

Raises:

  • (ArgumentError) —

    If the strings are not equal in length



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# File 'lib/rbnacl/util.rb', line 182

def verify16!(one, two)
  check_length(one, 16, "First message")
  check_length(two, 16, "Second message")
  c_verify16(one, two)
end

.verify32(one, two) ⇒ Boolean

Compare two 32 byte strings in constant time

This should help to avoid timing attacks for string comparisons in your application. Note that many of the functions (such as HmacSha256#verify) use this method under the hood already.

Parameters:

  • one (String) —

    String #1

  • two (String) —

    String #2

Returns:

  • (Boolean) —

    Well, are they equal?



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# File 'lib/rbnacl/util.rb', line 132

def verify32(one, two)
  return false unless two.bytesize == 32 && one.bytesize == 32
  c_verify32(one, two)
end

.verify32!(one, two) ⇒ Boolean

Compare two 32 byte strings in constant time

This should help to avoid timing attacks for string comparisons in your application. Note that many of the functions (such as HmacSha256#verify) use this method under the hood already.

Parameters:

  • one (String) —

    String #1

  • two (String) —

    String #2

Returns:

  • (Boolean) —

    Well, are they equal?

Raises:

  • (ArgumentError) —

    If the strings are not equal in length



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# File 'lib/rbnacl/util.rb', line 149

def verify32!(one, two)
  check_length(one, 32, "First message")
  check_length(two, 32, "Second message")
  c_verify32(one, two)
end

.zero_pad(n, message) ⇒ String

Pad a string out to n characters with zeros

Parameters:

  • n (Integer) —

    The length of the resulting string

  • message (String) —

    the message to be padded

Returns:

  • (String) —

    A string, n bytes long

Raises:



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# File 'lib/rbnacl/util.rb', line 61

def zero_pad(n, message)
  len = message.bytesize
  if len == n
    message
  elsif len > n
    raise LengthError, "String too long for zero-padding to #{n} bytes"
  else
    message + zeros(n - len)
  end
end

.zeros(n = 32) ⇒ String

Returns a string of n zeros

Lots of the functions require us to create strings to pass into functions of a specified size.

Parameters:

  • n (Integer) (defaults to: 32) —

    the size of the string to make

Returns:

  • (String) —

    A nice collection of zeros



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# File 'lib/rbnacl/util.rb', line 21

def zeros(n = 32)
  zeros = "\0" * n
  # make sure they're 8-bit zeros, not 7-bit zeros.  Otherwise we might get
  # encoding errors later
  zeros.respond_to?(:force_encoding) ? zeros.force_encoding("ASCII-8BIT") : zeros
end