Convertible Authenticated Encryption Scheme Research Articles

Hybrid Publicly Verifiable Authenticated Encryption Scheme Based on Chaotic Maps and Factoring Problems

ABSTRACTA new public authenticated encryption scheme based on chaotic maps and factoring problems is proposed. The chaos-based cryptosystem offers an encryption scheme with several advantages including secure transfer, high speed encryption, and reasonable computational overheads. Cryptographic factoring and chaotic system are employed to enhance the security of our convertible authenticated encryption scheme. The encryption, signature generation, signature verification, and message recovery are discussed in details. Several security attacks are proposed to illustrate the system shield through chaotic maps and factoring problems. The performance analysis of the proposed scheme show a much improved performance over existing techniques.

A New Self-Certified Convertible Authenticated Encryption Scheme Based on Discrete Logarithm Problem

The convertible authentication encryption (CAE) scheme, enables the signatory to send a secret message and its associated signature to a designated receiver. If some dispute happens, then the receiver has the ability to get ordinary signature by converting the ciphertext signature. The receiver can solely perform this signature conversion without any extra computational costs. The recipient of the signature can prove himself that he/she is the actual designated recipient. We incorporate self - certified public key (SCPK) systems into a CAE scheme to propose our CAE scheme with authentication and computationally indistinguishable. Our CAE scheme provide robust security and apply it to different online financial applications. The security analysis reflects that, our CAE scheme satisfies all the security requirements. Moreover, it does not require additional certificate verification because the public key authentication and signature verification can be done in single logical step. Finally, from the result of performance analysis shows, that the presented CAE scheme is cost efficient than the existing Wu et al.’s scheme.

Convertible Multi-authenticated Encryption Scheme for Data Communication

A convertible authenticated encryption scheme allows the signer to create a valid authenticated ciphertext such that only the specified receiver can simultaneously recover and verify the message. To protect the receiver's benefit of a later dispute on repudiation, the receiver has the ability to convert the signature into an ordinary one that can be verified by anyone. However, the previous proposed convertible authenticated encryption schemes are not adequate when the signers are more than one. Based on elliptic curve cryptography, this paper will propose a new efficient convertible multi-authenticated encryption scheme for mobile communication or hardware-limited users. The proposed scheme provides the following advantages: (1) The size of the generated authenticated ciphertext is independent of the number of total signers. (2) The signature is cooperatively produced by a group of signers instead of a signal signer. (3) Except for the designated recipient, no one can derive the signed message and verify its corresponding signature. (4) When a later dispute on repudiation, the receiver has the ability to prove the dishonesty of the signers by revealing an ordinary signature that can be verified by any verifier (or judge) without the cooperation of the signers. (5) The computation costs for the verifier will not significantly increase even if the signer group is expanded. Moreover, we also proposed the convertible multi-authenticated encryption protocol in multi-verifier setting for applications.

RPCAE: a novel revocable proxy convertible authenticated encryption scheme

Convertible authenticated encryption schemes allow a signer to produce an authenticated ciphertext and only a designated recipient can verify its signature. Such schemes also provide an additional signature conversion mechanism to convince anyone of signer's dishonesty when a later dispute occurs. Proxy signature schemes allow an authorized proxy signer to generate proxy signatures on behalf of the original signer according to the predefined signing policy. In this paper, we elaborate on the merits of both systems to propose the first novel Revocable Proxy Convertible Authenticated Encryption (RPCAE) scheme for confidential applications with proxy delegation. The revocation protocol is rather simple and incurs no extra computational efforts. Moreover, the IND-CCA2 and the EF-CMA security for the proposed scheme are also formally proved.

Convertible Authenticated Encryption Scheme with Hierarchical Access Control

Convertible authenticated encryption (CAE) scheme with hierarchical access control has crucial benefits to the transmission of digital evidence. Such a scheme allows a judicial policeman to generate an authenticated ciphertext and only a designated investigator of Investigation of Bureau, Ministry of Justice (MJIB) has the ability to decr ypt the ciphertext and verify the corresponding signature. The designated investigator can further convert the ciphertext into an or dinary signature and give it to a judge or a prosecutor for the litigation process. A senior manager of MJIB also has the right to take over either one or all ciphertext, i.e., digital evidence, intended for his subordinate. The underlying security assumption of our proposed scheme is based on the bilinear Diffie-Hellman problem (BDHP). We prove that the proposed scheme achieves the security requirement of confidentiality against indistinguishability under adaptive chosen-ciphertext attacks (IND-CCA2) and that of unforgeability against existential forgery under adaptive chosen-message attacks (EF-CMA) in the random oracle model. Compared with related works, the proposed scheme not only provides better functionalities, but also has provable security.

Toward Efficient Convertible Authenticated Encryption Schemes Using Self-Certified Public Key System

Convertible authenticated encryption (CAE) schemes enable the signer to send a confidential message and its corresponding signature to the designated recipient. The recipient can also convert the signature into a conventional one which can be verified by anyone. Integrating the properties of self-certified public key systems, this paper presents efficient and computationally indistinguishable self-certified CAE schemes for strengthening the security of E-Commerce applications. Additionally, we also adapt the proposed schemes to elliptic curve systems for facilitating the applications of limited computing power and insufficient storage space. The proposed schemes are secure against known existential active attacks, satisfy the semantic security requirement, and have the following advantages: (i) No extra certificate is required since the tasks of authenticating the public key and verifying the signature can be simultaneously carried out within one step, which helps reducing computation efforts and communication overheads. (ii) In case of a later dispute, the recipient can convert the signature into an ordinary one for the public arbitration. (iii) The signature conversion can be solely performed by the recipient without additional computation efforts or communication overheads. (iv) The recipient of the signature can prove himself, if needed, to anyone that he is actually the designated recipient.

Provably secure proxy convertible authenticated encryption scheme based on RSA

To engage with complicated business operations, we propose a proxy convertible authenticated encryption (CAE) scheme based on RSA assumption to resolve the delegation problem for confidential transactions. The proposed scheme enables an authorized proxy signer to produce a proxy authenticated ciphertext such that only the designated recipient can validate it for assuring the transaction privacy. In case of a later repudiation, the designated recipient can just release the converted proxy signature for public arbitration without extra computation efforts or communication overheads. Moreover, the security requirement of confidentiality against indistinguishability under adaptive chosen-ciphertext attacks (IND-CCA2) and that of unforgeability against existential forgery under adaptive chosen-message attacks (EF-CMA) are given in the random oracle model. To the best of our knowledge, the proposed scheme is the first provably secure proxy CAE scheme based on RSA assumption.

A secure and efficient convertible authenticated encryption scheme with message linkages using elliptic curve cryptosystem

A convertible authenticated encryption scheme is very useful for transmitting a confidential message in insecure communication networks. This paper proposes a convertible authenticated encryption scheme with message linkages for message flows using Elliptic Curve Cryptography (ECC). The proposed scheme has the following advantages. (1) It can provide non-repudiation when the signer repudiates his/her signature by adding conversion phase. (2) It can greatly reduce computation efforts for that the tasks of verifying the signature and authenticating the public key can be simultaneously carried out in one step. (3) It is

Encryption scheme for weighted threshold authentication

A convertible authenticated encryption(CAE) scheme allows designated recipients to simultaneously recover and verify the message,while a convertible multi-authenticated encryption(CAME) scheme allows a signing group with multiple signers to generate a multi-authenticated signature-ciphertext on the chosen message.Motivated by the weighted threshold secret sharing scheme based on the Chinese remainder theorem,we construct a weighted threshold access structure.Furthermore,we propose a weighted threshold authenticated encryption(CWAE) scheme.In the proposed scheme,each group member is assigned a positive weight according to its significance.A subset of the group can generate the signature-ciphertext if and only if the sum of weights assigned to its members exceeds a certain threshold.

A publicly verifiable PCAE scheme for confidential applications with proxy delegation

ABSTRACTWith the diversity of business transactions, new application requirements will emerge. Many confidential transactions, such as online auctions and bank savings withdrawals, sometimes might be conducted by an authorized proxy. In this paper, we propose a bilinear pairing‐based proxy convertible authenticated encryption scheme. The proposed scheme allows the delegated proxy signer to generate an authenticated ciphertext in behalf of the original signer while only the designated recipient is able to decrypt the ciphertext and verify the proxy signature. To benefit the encryption of a large message, we further present another variant with message linkages. Both schemes are publicly verifiable, that is, the designated recipient can convert the ciphertext into an ordinary proxy signature for public verification. In addition, the security requirement of confidentiality against indistinguishability under adaptive chosen‐ciphertext attacks and that of unforgeability against existential forgery under adaptive chosen‐message attacks are proved in random oracle models. Copyright © 2011 John Wiley & Sons, Ltd.

Improved convertible authenticated encryption scheme with provable security

Convertible authenticated encryption (CAE) schemes allow a signer to produce an authenticated ciphertext such that only a designated recipient can decrypt it and verify the recovered signature. The conversion property further enables the designated recipient to reveal an ordinary signature for dealing with a later dispute over repudiation. Based on the ElGamal cryptosystem, in 2009, Lee et al. proposed a CAE scheme with only heuristic security analyses. In this paper, we will demonstrate that their scheme is vulnerable to the chosen-plaintext attack and then further propose an improved variant. Additionally, in the random oracle model, we prove that the improved scheme achieves confidentiality against indistinguishability under adaptive chosen-ciphertext attacks (IND-CCA2) and unforgeability against existential forgery under adaptive chosen-message attacks (EF-CMA).

Cryptanalysis of a convertible authenticated encryption scheme based on the ElGamal cryptosystem

A convertible authenticated encryption scheme allows a designated recipient to retrieve an authenticated ciphertext and convert the authenticated ciphertext into an ordinary signature. Recently, Lee, Hwang, and Tzeng proposed a new convertible authenticated encryption scheme based on the ElGamal cryptosystem. In this paper, we show that the Lee-Hwang-Tzeng scheme is not secure against chosen plaintext attacks. In addition, we give a solution to repair it.

A NEW CONVERTIBLE AUTHENTICATED ENCRYPTION SCHEME BASED ON THE ELGAMAL CRYPTOSYSTEM

A convertible authenticated encryption scheme allows a designated receiver to retrieve an authenticated ciphertext and convert the authenticated ciphertext into an ordinary signature. The receiver can prove the dishonesty of the sender to anyone if the sender repudiates his/her signature. Recently, many researchers have proposed convertible authenticated encryption schemes based on cryptological algorithms. In this paper, the authors shall present a new convertible authenticated encryption scheme based on the ElGamal cryptosystem. The proposed scheme is more efficient than Wu-Hsu's scheme in terms of computational complexity.

Efficient self-certified proxy CAE scheme and its variants

Elaborating on the merits of proxy signature schemes and convertible authenticated encryption (CAE) schemes, we adopt self-certified public key systems to construct efficient proxy CAE schemes enabling an authorized proxy signer to generate an authenticated ciphertext on behalf of the original signer. To satisfy the requirement of confidentiality, only the designated recipient is capable of decrypting the ciphertext and verifying the proxy signature. A significant advantage of the proposed schemes is that the proxy signature conversion process takes no extra cost, i.e., when the case of a later dispute over repudiation occurs, the designated recipient can easily reveal the ordinary proxy signature for the public arbitration. If needed, the designated recipient can also convince anyone that he is the real recipient. In addition, integrating with self-certified public key systems, our schemes can earn more computational efficiency, since authenticating the public key and verifying the proxy signature can be simultaneously carried out within one-step.

Selectively Convertible Authenticated Encryption in the Random Oracle Model

Conventionally, a verified digital signature releases information about both the signing event and the signed content simultaneously, where the signing event proves the truth that someone actually signed something. However, in many cases, the information of the signing event and the signed content have different uses and distinct degrees of importance on various occasions. In such cases, the conventional digital signature, the current authenticated encryption schemes and the current signcryption schemes cannot satisfy the needs of selectively releasing either the information about the signing event or that about the signed content or both depending on the situation. In this paper, we shall propose a selectively convertible authenticated encryption scheme where either the sender or the designated receiver can selectively convert the encryption such that the signing event and that of the signed content can be released adaptively. The security of the scheme is proved in the random oracle model. Applications based on the proposed scheme are also introduced.

Convertible multi-authenticated encryption scheme

A convertible authenticated encryption (CAE) scheme allows the signer to generate a valid authenticated ciphertext on his chosen message such that only the designated recipient can retrieve the message. Further, the recipient has the ability to convert the authenticated ciphertext into ordinary signature in case of a dispute or repudiation. The previous proposed CAE schemes can only allow one signer to produce the authenticated ciphertext. It might be inadequate for multiparty environments. In this paper, we elaborate on the merits of CAE and multi-signature schemes to propose a convertible multi-authenticated encryption scheme which has the following advantages: (i) The size of the generated authenticated ciphertext is independent of the number of total participating signers. (ii) Except for the designated recipient, no one can obtain the signed message and verify its corresponding signature. (iii) The signature is cooperatively produced by a group of signers instead of a single signer. (iv) In case of a later dispute on repudiation, the recipient has the ability to convert the authenticated ciphertext into an ordinary one for convincing anyone of the signers’ dishonesty.

Generalized convertible authenticated encryption schemes for smart card applications

Generalized convertible authenticated encryption schemes for smart card applications

Cryptanalysis and Improvement of Practical Convertible Authenticated Encryption Schemes Using Self-Certified Public Keys

A convertible authenticated encryption scheme allows a specified recipient to recover and verify a message simultaneously. Moreover the recipient can prove the dishonesty of the sender to any third party if the sender repudiates her signature later. Recently, Lv et al. (2005) showed that the Wu et al.'s (1999) and the Huang et al.'s (2003) convertible authenticated encryption schemes cannot provide the semantic security of encrypted messages. Then they proposed a practical convertible authenticated encryption scheme using self-certified public keys, and extended it to one with message linkages when the signed message is large. In this paper, we show that the verifier can recover messages if given many triples of message, signature and ciphertext in the Lv et al.'s basic convertible authenticated encryption scheme. Finally we propose a new improvement to these schemes to overcome this weakness and to improve its efficiency.

Practical convertible authenticated encryption schemes using self-certified public keys

A convertible authenticated encryption scheme allows a designated receiver to recover and verify a message simultaneously, during which the recipient can prove the dishonesty of the sender to any third party if the sender repudiates her signature later. In this paper, after showing some weaknesses in Wu and Hsu [T. Wu, C. Hsu, Convertible authenticated encryption scheme. The Journal of Systems and Software 62 (2002) 205–209] and Huang and Chang [H. Huang, C. Chang, An efficient convertible authenticated encryption scheme and its variant, in: Proceedings of the ICICS2003-Fifth International Conference on Information and Communications Security, Springer-Verlag, LNCS 2836, 2003, p. 382] convertible authenticated encryption schemes, we propose a practical convertible authenticated encryption scheme using self-certified public keys and then extend it to one with message linkages when the signing message is large. Each scheme could provide semantic security of the message, the signer’s public key can be simultaneously authenticated in checking a signature’ validity and only under the cooperation of the recipient could a verifier know to whom a specific signature is sent. Finally, we give a variant that could make a verifier know to whom a signature is sent while verifying its validity.

On the security of a convertible authenticated encryption

In this paper, we give security analysis to the convertible authenticated encryption scheme of Hung-Yu Chien [H.-Y. Chien, Convertible authenticated encryption scheme without using conventional one-way function, Informatica 14 (4) (2003) 1–9, Institute of Mathematics and Inforamtica, ISSN 0868-4952], and show that H.Y. Chien scheme have forgeability and repudiation; at the same time, we give the corresponding attack. Finally, we propose an improved publicly verifiable authenticated encryption schemes based on the Hung-Yu Chien Scheme. As for efficiency, the computation cost and communication overhead of our improved schemes are as small as the original schemes and in comparison with the original scheme, our improved scheme is more secure.