Class: Krypt::FFI::Digest

Inherits:
Object
  • Object
show all
Includes:
LibC
Defined in:
lib/krypt/provider/ffi/digest.rb

Overview

A Krypt::Digest implementation using FFI.

Defined Under Namespace

Classes: NativeHandle

Instance Method Summary collapse

Constructor Details

#initialize(provider, type) ⇒ Digest

call-seq:

Krypt::FFI::Digest.new(provider, name_or_oid) -> Digest

Creates a Digest using a C struct krypt_provider as provider argument. The provider is typically obtained by a separate FFI call to a publicly visible function offered by the implementation of the krypt Provider C API. name_or_oid can be either the name of the digest algorithm to be used (e.g. “SHA1”) or the OID String uniquely identifying the digest algorithm.



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# File 'lib/krypt/provider/ffi/digest.rb', line 20

def initialize(provider, type)
  unless (@handle = interface_for_name(provider, type))
    unless (@handle = interface_for_oid(provider, type))
      raise Krypt::Provider::ServiceNotAvailableError.new("Unknown digest algorithm: #{type}")
    end
  end
end

Instance Method Details

#block_length ⇒ Object

call-seq:

digest.block_length -> integer

Returns the block length of the digest algorithm, i.e. the length in bytes of an individual block. Most modern algorithms partition a message to be digested into a sequence of fix-sized blocks that are processed consecutively.

Example

digest = Krypt::Digest::SHA1.new
puts digest.block_length # => 64



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# File 'lib/krypt/provider/ffi/digest.rb', line 132

def block_length
  read_length(@handle.interface[:md_block_length])
end

#digest(data = nil) ⇒ Object

call-seq:

digest.digest([string]) -> String

When called with no arguments, the result will be the hash of the data that has been fed to this Digest instance so far. If called with a String argument, the hash of that argument will be computed.

Example

digest = Krypt::Digest::SHA256.new
result = digest.digest('First input')

is equivalent to

digest = Krypt::Digest::SHA256.new
digest << 'First input' # equivalent to digest.update('Second input')
result = digest.digest



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# File 'lib/krypt/provider/ffi/digest.rb', line 82

def digest(data=nil)
  if data
    ret = digest_once(data)
  else
    ret = digest_finalize
  end
  reset
  ret
end

#digest_length ⇒ Object

call-seq:

digest.digest_length -> integer

Returns the output size of the digest, i.e. the length in bytes of the final message digest result.

Example

digest = Krypt::Digest::SHA1.new
puts digest.digest_length # => 20



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# File 'lib/krypt/provider/ffi/digest.rb', line 115

def digest_length
  read_length(@handle.interface[:md_digest_length])
end

#hexdigest(data = nil) ⇒ Object

call-seq:

digest.hexdigest([string]) -> String

Works the with the same semantics as Digest#digest with the difference that instead of the raw bytes the hex-encoded form of the raw representation is returned.



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# File 'lib/krypt/provider/ffi/digest.rb', line 100

def hexdigest(data=nil)
  Krypt::Hex.encode(digest(data))
end

#name ⇒ Object

call-seq:

digest.name -> string

Returns the sn of this Digest instance.

Example

digest = Krypt::Digest::SHA512.new
puts digest.name # => SHA512



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# File 'lib/krypt/provider/ffi/digest.rb', line 147

def name
  name_ptr = FFI::MemoryPointer.new(:pointer)
  result = @handle.interface[:md_name].call(@handle.container, name_ptr)
  raise_on_error("Error while obtaining digest name", result)

  name_ptr.read_pointer.get_string(0)
end

#reset ⇒ Object

call-seq:

digest.reset -> self

Resets the Digest in the sense that any Digest#update that has been performed is abandoned and the Digest is set to its initial state again.



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# File 'lib/krypt/provider/ffi/digest.rb', line 35

def reset
  result = @handle.interface[:md_reset].call(@handle.container)
  raise_on_error("Error while resetting digest", result)
  self
end

#update(data) ⇒ Object Also known as: <<

call-seq:

digest.update(string) -> aString

Not every message digest can be computed in one single pass. If a message digest is to be computed from several subsequent sources, then each may be passed individually to the Digest instance.

Example

digest = Krypt::Digest::SHA256.new
digest.update('First input')
digest << 'Second input' # equivalent to digest.update('Second input')
result = digest.digest



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# File 'lib/krypt/provider/ffi/digest.rb', line 56

def update(data)
  result = @handle.interface[:md_update].call(@handle.container, data, data.length)
  raise_on_error("Error while updating digest", result)
  self
end