New scheme for digital multisignatures

When two individual users wish to carry on a secure conversation, they can use the well-known RSA public key cryptosystem in doing so. This cryptosystem provides to these users both data secrecy and digital signature in a very efficient manner. However, in many applications, multiple users need to sign a document. In this letter, the authors propose a modified scheme, based on the RSA scheme, which will allow any number of users to sign a document and send it secretly to the receiver. The length of ciphertext remains constant, no matter how great the number of signatories. The trade-off is that the processing times required for generating the multisignature, and for verifying multisignatures, depend on the number of signatories.