Wwg" ddlZddlmZddlmZddlmZddlmZdZ dZ dee e fd e fd Z d Zd Zd ZdefdZ dde deded e fdZy)N)md5)Union)generic) rc4_encrypts (N^NuAdNV..h>/ dSizc|tzdd}t|}|j|tjd|j }|j||j||dk\r|s|jd|j }|dk\r,tdD]} t|d|j } |d|S)z{ Implementation of algorithm 3.2 of the PDF standard security handler, section 3.5.2 of the PDF 1.6 reference. N zz)compute_o_value_legacy..]s/aAE/)compute_o_value_legacy_prepr rrbytes) owner_pwduser_pwdrrkeyvalnew_keyrs @rcompute_o_value_legacyr8Gsv &if =C..4H c8 $C axq" ,A/3//Ggs+C , Jrc|tzdd}t|}|j}|dk\r)tdD]}t|j}|d|}|S)z$ Steps 1-4 of algorithm 3.3 Nrr r )r rrr)rrrrrrr5s rr1r1dsm..4H H AxxzH axr .A8}++-H . 7F C Jrc Nt|dd|||d}t|t}||fS){ Implementation of algorithm 3.4 of the PDF standard security handler, section 3.5.2 of the PDF 1.6 reference. Tr)rrr )rrrrr5us rcompute_u_value_r2r@~s7 !!Q Wi$ C C,-A c6Mrrc 0 t|||||||}t}|jt|j||j } t || } t ddD]" t fd|D} t | | } $| dz|fS)r;r>r'r(c3(K|] }|z  ywr*r+r,s rr/z&compute_u_value_r34..s+!A+r0s)rrr r rrrr2) rrrrrrrr5rrr6r7rs @rcompute_u_value_r34rCs ! ) C AHH ! HHYxxzH c8 $C1b\(+s++'3'( ,  $$r shared_keyidnum generationc$tjd|dd}tjd|dd}||z|z}t|t|dzk(sJ|r|dz }t|j }|dt dt|dzS)a Function that does the key derivation for PDF's legacy security handlers. :param shared_key: Global file encryption key. :param idnum: ID of the object being written. :param generation: Generation number of the object being written. :param use_aes: Boolean indicating whether the security handler uses RC4 or AES(-128). :return: zrUs %5 .b%U "3:4&5%5%r=B44!4/24 4r