Unformatted text preview: E ( n,e,d ) ( m ) = m e mod n . For ciphertext c ∈ Z * n , the cleartext is D ( n,e,d ) ( c ) = c d mod n . Is the above block cipher as secure as a typical block cipher (like AES)? Why or why not? 4 Sharing RSA Modulus A company needs to set up the keys for its employees. So the company chooses an RSA modulus n and multiple pairs of encryption/decryption exponents ( e 1 ,d 1 ) ,..., ( e k ,d k ) . Then for each i , the i th employee uses the public key ( n,e i ) and the private key ( n,d i ) . What is the security problem of such a key setup? 1...
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 Spring '10
 SHENGZHONG
 Cryptography, Computer Security, Block cipher, decryption key

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