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# coding: utf-8
# typed: strict
# frozen_string_literal: true
require 'digest'
require 'openssl'
class PDF::Reader
# Decrypts data using the AESV3 algorithim defined in the PDF 1.7, Extension Level 3 spec.
# Requires a decryption key, which is usually generated by PDF::Reader::KeyBuilderV5
#
class AesV3SecurityHandler
def initialize(key)
@encrypt_key = key
@cipher = "AES-256-CBC"
end
##7.6.2 General Encryption Algorithm
#
# Algorithm 1: Encryption of data using the RC4 or AES algorithms
#
# used to decrypt RC4/AES encrypted PDF streams (buf)
#
# buf - a string to decrypt
# ref - a PDF::Reader::Reference for the object to decrypt
#
def decrypt( buf, ref )
cipher = OpenSSL::Cipher.new(@cipher)
cipher.decrypt
cipher.key = @encrypt_key.dup
cipher.iv = buf[0..15]
cipher.update(buf[16..-1]) + cipher.final
end
end
end
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