數位簽章近年發展漸趨成熟，但亦能利用特殊的簽章方案來因應特殊情況下傳統簽章所無法達成的效果與特性。
變色龍簽章是一種基於離散對數的非交互式數位簽章方案，以傳統簽章為基礎，在雜湊函數上使用特殊的變色龍雜湊函數，能夠在出現有疑慮的簽署碼時，可利用兩組碰撞的簽署碼，透過變色龍雜湊函數運算產生更多的碰撞簽署碼以質疑該簽章的正確性，進而否認該簽章內容。
改良變色龍簽章方案時，為了擁有更輕便的金鑰分發，將變色龍簽章改採用植基於個人識別的公鑰系統；為了使簽章者擁有主動否認簽章內容之能力，將原先使用接收者或公正第三方之金鑰轉換為使用簽章者之金鑰；為了強化其不可轉讓性而採用雙重簽章方法；綜合而成的簽章方案稱為植基於個人識別的公鑰系統下之自主式變色龍簽章。
該簽章可應用於針對特定接收者之可驗證的秘密透漏，並與將環簽章應用於匿名的秘密透漏做比較評估；最後實作植基於個人識別的公鑰系統下之自主式變色龍簽章系統，以驗證此簽章方案之可行性。

Chameleon Signature was introduced to enhance the confidentiality and privacy of electronic transactions. By adopting Chameleon Signature, the recipient can not disclose the contents of the signed information to any third party without the signer's consent. In order to improve the un-forgeability, non-transferability, and efficiency of Chameleon Signature, this paper proposed a modified ID-based Chameleon Signature scheme Determined by Signer, called ICS scheme. ICS has some advantages including (1) the signer can deny the signatures give to the recipient by himself, (2) non-transferability is improved by using double signature, and (3) providing a relaxing public key infrastructure. From the implementing and evaluating the ICS scheme, we prove that the design of our proposed ICS scheme is feasible.

目錄
第一章 緒論	1
1.1 研究背景與動機	1
1.2 研究目的	1
第二章 文獻探討	3
2.1 SHA-1	3
2.2 RSA數位簽章	4
2.3  DSS數位簽章	5
2.4 變色龍簽章	6
2.5 植基於個人識別的公鑰系統下之變色龍簽章	10
2.6 環簽章方案	10
第三章 植基於個人識別的公鑰系統下之 自主式變色龍簽章	13
3.1 植基於個人識別的公鑰系統下之自主式變色龍雜湊	13
3.2 植基於個人識別的公鑰系統下之自主式變色龍簽章之簽署	14
3.3 植基於個人識別的公鑰系統下之自主式變色龍簽章之驗證	15
3.4 植基於個人識別的公鑰系統下之自主式變色龍簽章之碰撞生成	16
第四章 分析與比較	18
4.1 安全性分析	18
4.2 比較評估	18
第五章 實作驗證	25
5.1 變色龍簽章實作驗證	25
5.2 變色龍簽章雜湊值碰撞生成實作	30
第六章 結論	36
參考文獻	38
 
圖目錄
圖 1 環簽章	12
圖 2 雜湊值生成介面	27
圖 3 變色龍雜湊值生成介面	28
圖 4 接收者簽章介面	29
圖 5 簽章者簽章介面	30
圖 6 變色龍雜湊值碰撞生成介面	32
 
表目錄
表 1 簽章方案特性比較表	22
表 2 應用於秘密透漏之簽章方案比較表	24
表 3 碰撞生成範例數據圖	33

參考文獻
[1]	Adi Shamir : Identity-based cryptosystems and signature schemes. In: Advances in Cryptology – CRYPTO’84. Volume 196 of LNCS., Springer-Verlag (1984) 47–53.
[2]	D. Chaum, H. Antwerpen, Undeniable signatures. In: Advances in Cryptology – CRYPTO’89. Volume 435 of LNCS., Springer-Verlag (1991) 212–216.
[3]	D. Chaum, E. van Heijst, B. Pfitzmann, Cryptographically strong undeniable signatures, unconditionally secure for the signer. In Proc. of Advances in Cryptology – CRYPTO’91. Volume 576 of LNCS., Springer-Verlag (1991) 470–ff.
[4]	D. Chaum, Zero-knowledge undeniable signature. In Advances in Cryptology–EUROCRYPT’90, Lect. Notes Comp. Sci., vol. 473, pp. 458–464. Springer-Verlag, 1990.
[5]	Federal Information Processing Standards Publication (FIPS PUB) 180-1, Announcing the Standard for Secure Hash Standard, 1995 April 17.
[6]	Federal Information Processing Standards Publication (FIPS PUB) 186-2, Digital Signature Standard (DSS), Federal Information Processing Standards Publication, 2000 January 27.
[7]	G. Ateniese and B. de Medeiros. Identity-Based Chameleon Hash and Applications. In Ari Juels, ed., Proc. of Financial Cryptography (FC 2004), Lect. Notes Comp. Sci., vol. 3110, pp. 164–180. Springer-Verlag, 2004.
[8]	Getin Kaya Koc. High-Speed RSA Implementation. RSA Laboratories RSA Data Security, Inc. 100 Marine Parkway. Suite 500 Redwood City. CA 94065-1031.
[9]	H. Krawczyk, T. Rabin, Chameleon signatures. In Proceedings of NDSS 2000.(2000) 143–154.
[10]	K. Nyberg and R. A. Rueppel. Message recovery for signature schemes based on the discrete logarithm problem. In Designs, Codes, and Cryptography, vol. 7(1–2), pp. 61–81. Kluwer Academic Publishers, 1996.
[11]	Non-Repudiation in the Digital Environment. Adrian McCullagh., Willian Caelli. http://firstmonday.org/htbin/cgiwrap/bin/ojs/index.php/fm/article/view/778/687
[12]	R. Gennaro, S. Halevi, and T. Rabin. Secure hash-and-sign signatures without the random oracle. In Advances in Cryptology–EUROCRYPT’99, Lect. Notes Comp. Sci., vol. 1592, pp. 123–139. Springer-Verlag, 1999.
[13]	Ronald L. Rivest, Adi Shamir, and Yael Tauman, How to Leak a Secret: Theory and Applications of Ring Signatures, In Advances in Cryptology – CRYPTO’84, Lecture Notes in Computer Science, vol.2248, pp.552-565, 2001.
[14]	RSA Labs: RSA Cryptography Standard: EMSAPSS – SKCS#1 v2.1. (2002).
[15]	S. Micali and R. Rivest. Transitive signature schemes. In B. Preneel, ed., Topics in Cryptology–RSA-CT’02, Lect. Notes Comp. Sci., vol. 2271, pp. 236–243. Springer-Verlag, 2002.