Digital Signature forming and keys protection based on person’s Characteristics Ahmed B. Elmadani Dept. of Computer Science Faculty of Science Sebha University Sebha Libya e-mail:
[email protected]
Abstract—In today's commercial environment, establishing a framework for the authentication came with different challenges, need of secure document exchange, secure bank transactions, and other e-commerce needs. Challenges are in term of confidentiality. Digital signature (DS) is the only means of achieving it. This paper shows a method in signing and verifying a document digitally online. A document is first signed, using a Secure Hash Algorithm – 160 (SHA-1), then protected by sender’s keys. The receiver verifies the signature using keys stored in the smart card (SMC) that is derived from his fingerprint. This paper investigates DSs techniques that is based on use of SMCs. It shows how true user identity can be verified when used keys are derived from human characteristics. The obtained results were translated in term of speed and security enhancement which is highly in demand of e-commerce society.
leaving the legal definition, and so their importance, somewhat confused [4]. DS is implemented by attaching a digital code to an electronically transmitted message that uniquely identifies the sender. DSs are equivalent to traditional handwritten signatures in many respects[2], properly implemented DSs are more difficult to forge than the handwritten type. DS schemes in the sense used here are cryptographically based, and must be implemented properly to be effective [4]. DSs can also provide non-repudiation, meaning that the signer cannot successfully claim they did not sign a message, while also claiming their private key remains secret; further, some nonrepudiation schemes offer a time stamp for the DS, so that even if the private key is exposed, the signature is valid nonetheless [2]. Digitally signed messages may be anything that can be represented as a bit or a string, examples include electronic mail, contracts, or a message sent via some other cryptographic protocol [3].
Keywords-component; Digital Signature, Hash Function, Public key system, and SHA-1.
I.
INTRODUCTION
Digital Signature (DS) is a mathematical scheme for demonstrating the authenticity of a digital message or document [1]. DS gives a recipient reason to believe that the message or document was created by a known sender, and that it was not altered in transit. DSs are commonly used for software distributions, financial transactions, and in other cases, where it is important, to detect forgery and tampering [11].
There are few commercial applications that supporting a DS, as an example Adobe, Excel, MS Outlook and etc... There are many common method in DS, one of them is to use a Public Key Cryptography, DSs are created and verified by cryptography. Public key cryptography employs an algorithm using two different, mathematically related "keys" [5], one "public key" for creating a DS or transforming data into a seemingly unintelligible form, the other key "private key" for verifying a DS or returning a message to its original form [1]. Disadvantage of this method is, if many people need to verify the signer's DS, the public key must be available or distributed to all of them, probably by the means of distributing it in an on-line repository or directory where it is easily accessible [4]. Thus, although many people may know the public key of a given signer and use it to verify that signer's signatures, they cannot discover that signer's private key and use it to forge DSs, but they can try[3].
The purpose of a DS is to guarantee that the individual sending the message or document really is who he or she claims to be. Where the goal is to facilitate both e-government and e-commerce applications over the Internet [1]. DSs are especially important for electronic commerce and are a key component of most authentication schemes. To be effective, DSs must be non forgeable. There are a number of different encryption techniques to guarantee this level of security [2]. DSs are often used to implement electronic signatures, a broader term that refers to any electronic data that carries the intent of a signature [1], but not all electronic signatures use DSs [11] In some countries, including the United States, India, and members of the European Union, electronic signatures have legal significance [3]. However, laws concerning electronic signatures do not always make clear whether they are digital cryptographic signatures in the sense used here,
Another fundamental process, named a "hash function", is used in both creating and verifying a DS. Hash function is an algorithm which creates a digital representation or a "fingerprint" in the form of a "hash value" of a standard length which is usually much smaller than the message's length but nevertheless substantially unique to it. Any changes to the message lead to producing an invariably different hash value
1
