IDEA子密鑰擴(kuò)展算法及其與MD5混合加密算法的研究
發(fā)布時(shí)間：2018-07-16 23:46
【摘要】：從公元前2000年至今,作為信息安全重要領(lǐng)域之一的學(xué)科,密碼學(xué)研究一直都未停止過,其在戰(zhàn)爭、軍事等方面發(fā)揮不可替代的作用,有重要的研究意義。但因?yàn)橛?jì)算機(jī)處理速度加快,密碼破譯方面的研究也飛速發(fā)展,導(dǎo)致到目前為止安全可行的密碼算法少之又少,國家標(biāo)準(zhǔn)的密碼體制更是寥寥無幾。本文圍繞兩種現(xiàn)有的加密算法:IDEA(International Data Encryption Algorithm,IDEA)和MD5(Message-digest Algorithm 5,MD5)遇到的不安全挑戰(zhàn)展開研究。本文的研究工作主要包含以下幾個(gè)方面:第一,闡述密碼學(xué)的課題發(fā)展歷史、研究背景及研究意義,著重對(duì)密碼學(xué)發(fā)展歷史及其分類進(jìn)行闡述。重點(diǎn)研究IDEA、MD5密碼體制的實(shí)現(xiàn)過程,包含加密過程、密鑰擴(kuò)展算法、解密過程及算法安全性。第二,針對(duì)IDEA弱密鑰問題提出一種改進(jìn)的子密鑰擴(kuò)展算法。首先通過對(duì)一組128位初始密鑰位進(jìn)行隨機(jī)散列;然后根據(jù)得到的隨機(jī)散列值利用同義詞鏈地址法生成若干個(gè)無線性關(guān)系的子密鑰,重復(fù)以上步驟直至生成52個(gè)子密鑰。對(duì)照原來的IDEA子密鑰擴(kuò)展算法,解決了原子密鑰擴(kuò)展算法的差分-線性分析及相關(guān)子密鑰攻擊對(duì)IDEA算法造成的挑戰(zhàn),保證了IDEA密碼算法的安全性。并且在程序?qū)崿F(xiàn)可接受的效率范圍內(nèi)實(shí)現(xiàn)此算法。實(shí)驗(yàn)證明,該算法解決了IDEA密碼算法的弱密鑰問題,且在效率方面比往期改進(jìn)后的子密鑰擴(kuò)展算法明顯提高。第三,針對(duì)MD5不安全及IDEA大明文下大密文空間的問題提出一種新的基于MD5和改進(jìn)后的IDEA混合加密算法。首先將明文作為輸入MD5算法的輸入,通過MD5算法加密完成后輸出密文;然后將輸出的密文作為改進(jìn)后IDEA密碼算法的輸入,根據(jù)改進(jìn)后IDEA對(duì)其進(jìn)行加密,加密完成后輸出固定長度的密文。并且在程序?qū)崿F(xiàn)可接受的效率范圍內(nèi)實(shí)現(xiàn)此算法。實(shí)驗(yàn)證明,當(dāng)明文空間大于256bits時(shí)綜合考慮算法效率、安全性及存儲(chǔ)空間,混合加密算法優(yōu)勢(shì)明顯。
[Abstract]:Since 2000 BC, as one of the important fields of information security, cryptography research has never stopped. It plays an irreplaceable role in war, military and so on, and has important research significance. However, due to the fast speed of computer processing and the rapid development of cryptographic decoding research, so far, there are very few secure and feasible cryptographic algorithms, and the national standard cryptosystem is even less. This paper focuses on the insecure challenges encountered by two existing encryption algorithms: idea (International data encryption algorithm) and MD5 (Message-digest Algorithm 5MD5). The research work of this paper mainly includes the following aspects: first, the development history, research background and research significance of the subject of cryptography are expounded, and the development history and classification of cryptography are emphasized. This paper focuses on the implementation of IDEAN MD5 cryptosystem, including encryption process, key extension algorithm, decryption process and algorithm security. Secondly, an improved subkey expansion algorithm is proposed for idea weak key problem. Firstly, a set of 128-bit initial key bits are randomly hashed, and then the sub-keys of several wireless relationships are generated by using the synonym chain address method according to the resulting random hash values, and the above steps are repeated until 52 sub-keys are generated. Compared with the original idea subkey expansion algorithm, the difference linear analysis of atomic key expansion algorithm and the challenge caused by related subkey attacks to idea algorithm are solved, and the security of idea cryptographic algorithm is ensured. The algorithm is implemented within the acceptable efficiency range of the program. Experimental results show that the algorithm solves the weak key problem of idea cipher algorithm, and its efficiency is much higher than that of the previous improved sub-key expansion algorithm. Thirdly, a new MD5 and improved idea hybrid encryption algorithm is proposed to solve the problem of MD5 insecurity and large ciphertext space under idea Daming. Firstly, the plaintext is taken as the input of MD5 algorithm, then the ciphertext is output after the encryption is completed by MD5 algorithm, and then the ciphertext output is used as the input of the improved idea cipher algorithm, which is encrypted according to the improved idea. Output a fixed length ciphertext after encryption is complete. The algorithm is implemented within the acceptable efficiency range of the program. The experimental results show that when the plaintext space is larger than 256bits, the hybrid encryption algorithm has the advantage of considering the efficiency, security and storage space of the algorithm.
【學(xué)位授予單位】：中北大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN918.4
本文編號(hào)：2128096
[Abstract]:Since 2000 BC, as one of the important fields of information security, cryptography research has never stopped. It plays an irreplaceable role in war, military and so on, and has important research significance. However, due to the fast speed of computer processing and the rapid development of cryptographic decoding research, so far, there are very few secure and feasible cryptographic algorithms, and the national standard cryptosystem is even less. This paper focuses on the insecure challenges encountered by two existing encryption algorithms: idea (International data encryption algorithm) and MD5 (Message-digest Algorithm 5MD5). The research work of this paper mainly includes the following aspects: first, the development history, research background and research significance of the subject of cryptography are expounded, and the development history and classification of cryptography are emphasized. This paper focuses on the implementation of IDEAN MD5 cryptosystem, including encryption process, key extension algorithm, decryption process and algorithm security. Secondly, an improved subkey expansion algorithm is proposed for idea weak key problem. Firstly, a set of 128-bit initial key bits are randomly hashed, and then the sub-keys of several wireless relationships are generated by using the synonym chain address method according to the resulting random hash values, and the above steps are repeated until 52 sub-keys are generated. Compared with the original idea subkey expansion algorithm, the difference linear analysis of atomic key expansion algorithm and the challenge caused by related subkey attacks to idea algorithm are solved, and the security of idea cryptographic algorithm is ensured. The algorithm is implemented within the acceptable efficiency range of the program. Experimental results show that the algorithm solves the weak key problem of idea cipher algorithm, and its efficiency is much higher than that of the previous improved sub-key expansion algorithm. Thirdly, a new MD5 and improved idea hybrid encryption algorithm is proposed to solve the problem of MD5 insecurity and large ciphertext space under idea Daming. Firstly, the plaintext is taken as the input of MD5 algorithm, then the ciphertext is output after the encryption is completed by MD5 algorithm, and then the ciphertext output is used as the input of the improved idea cipher algorithm, which is encrypted according to the improved idea. Output a fixed length ciphertext after encryption is complete. The algorithm is implemented within the acceptable efficiency range of the program. The experimental results show that when the plaintext space is larger than 256bits, the hybrid encryption algorithm has the advantage of considering the efficiency, security and storage space of the algorithm.
【學(xué)位授予單位】：中北大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN918.4
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