o &zh" @sddlZddlmZddlmZddlmZddlmZdZ ddZ d ee e fd e fd d Z d dZddZddZdefddZ dde deded e fddZdS)N)md5)Union)generic) rc4_encrypts (N^NuAdNV..h>/ dSizc Cs|tdd}t|}||td|}|||||dkr.|s.|d|}|dkrGtdD] } t|d|}q:|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 z]z)compute_o_value_legacy..)compute_o_value_legacy_prepr rrbytes) owner_pwduser_pwdrrkeyvalnew_keyrr*rcompute_o_value_legacyGs   r4cCsR|tdd}t|}|}|dkr!tdD]}t|}q|d|}|S)z$ Steps 1-4 of algorithm 3.3 Nrrr )r rrr)rrrrrrr1rrrr-ds  r-c Cs(t|dd|||dd}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 )rrrrr1urrrcompute_u_value_r2~s  r:rc s~t|||||||d}t}|t|||} t|| } tddD]tfdd|D} t| | } q&| d|fS)r5r8r#r$c3r%r&rr'r*rrr+r,z&compute_u_value_r34..s)rrr r rrrr.) rrrrrrrr1rrr2r3rr*rcompute_u_value_r34s$     r;F shared_keyidnum generationcCs~td|dd}td|dd}|||}t|t|dks&J|r,|d7}t|}|dtdt|dS)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: zuse_aespack1pack2r1rrrrlegacy_derive_object_keys  rE)F)r hashlibrtypingrpyhanko.pdf_utilsrpyhanko.pdf_utils.crypt._utilrr rr r.r"r4r-r:boolr;intrErrrrs2    1 9