Made available in DSpace on 2014-12-17T15:47:52Z (GMT). No. of bitstreams: 1 IsaacLOF_DISSERT.pdf: 3023517 bytes, checksum: 930863884e5d8399f785c0579333da82 (MD5) Previous issue date: 2010-02-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In this work will applied the technique of Differential Cryptanalysis, introduced in 1990 by Biham and Shamir, on Pap?lio s cryptosystem, developed by Karla Ramos, to test and most importantly, to prove its relevance to other block ciphers such as DES, Blowfish and FEAL-N (X). This technique is based on the analysis of differences between plaintext and theirs respective ciphertext, in search of patterns that will assist in the discovery of the subkeys and consequently in the discovery of master key. These differences are obtained by XOR operations. Through this analysis, in addition to obtaining patterns of Pap?ılio, it search to obtain also the main characteristics and behavior of Papilio throughout theirs 16 rounds, identifying and replacing when necessary factors that can be improved in accordance with pre-established definitions of the same, thus providing greater security in the use of his algoritm / Neste trabalho ser?a aplicada a t?cnica de Criptoan?lise Diferencial, introduzida por Biham e Shamir, sobre o algoritmo de criptografia Pap?lio, desenvolvido por Karla Ramos, a fim de testar e, principalmente, provar sua relev ancia em rela??o a outras cifras de blocos como DES, Blow- Fish e FEAL-N(X). Esta t?ecnica tem por base a an?alise das diferenc?as entre os pares de textos claros e a diferenc?a entre as suas respectivas cifras, em busca de padr oes que auxiliar?o nas descobertas das sub chaves e consequentemente na descoberta da chave mestra, na qual est?a a seguran?a da cifra. Estas diferenc?as s?o obtidas atrav?s de opera??es XOR. Busca-se, com esta an?lise, al?m da obten??o de padr?es do Pap?lio, obter-se tamb?m as principais caracter?sticas e o comportamento do Pap?lio durante seus 16 ciclos, identificando e substituindo quando necess?rio, os fatores que podem ser melhorados de acordo com as defini??es pr?e estabelecidas do mesmo, para oferecer maior seguran?a na utiliza??o de sua cifra