Source-of-leakage detectable e-mail address forming, sending and detection

Abstract

Provides e-mail address forming methods to know with certainty whether or not an e-mail address was leaked. A method includes: sending a receiver's identifier and a sender's identifier to a receiver's mail server; computing a value which is encrypted by the mail server with a secret key, the secret key being only possessed by the mail server, from the receiver's identifier, the sender's identifier, and a nonce issued by the mail server, and sending the value to a receiver; and forming an e-mail address (LD address) to be used by a sender who sends a mail to a receiver, by attaching a receiver's domain name to the encrypted value. Furthermore, the present invention has an e-mail address sending method, and an e-mail sending system which uses the e-mail address forming method to know with certainty whether or not the user of an e-mail address leaked the e-mail address.

1 . An e-mail address forming method, comprising the steps of: 
 sending a receiver's identifier A and a sender's identifier B to a receiver's mail server AMS;    computing a value {A, B, N}K which is encrypted by the mail server AMS with a secret key K, the secret key K being only possessed by the mail server AMS, from the receiver's identifier A, the sender's identifier B, and a nonce N issued by the mail server AMS, and sending the value {A, B, N}K to a receiver; and    forming an e-mail address (LD address) to be used by a sender who sends an e-mail to a receiver, by attaching a receiver's domain name to the encrypted value {A, B, N}K.    
   
   
       2 . An e-mail sending method for a sender to send an e-mail to a receiver, comprising the steps of: 
 sending a receiver's identifier A and a sender's identifier B to a receiver's mail server AMS;    computing a value {A, B, N}K which is encrypted by the mail server AMS with a secret key K, the secret key K being only possessed by the mail server AMS, from the receiver's identifier A, the sender's identifier B, and a nonce N issued by the mail server AMS, and sending the value {A, B, N}K to a receiver;    forming an e-mail address (LD address) to be used by a sender who sends an e-mail to a receiver, by attaching a receiver's domain name to the encrypted value {A, B, N}K; and    sending the formed e-mail address to the sender.    
   
   
       3 . An e-mail sending method, comprising the steps of: 
 disclosing a receiver's public address;    sending the public address and a message M B  for requesting a permission of communication with a sender to a receiver's mail server AMS via a sender's mail server BMS;    causing the mail server AMS to send the message M B  to a receiver;    causing the mail server AMS to receive an address issuance permission from the receiver who received and read the message;    computing a value {A, B, N}K which is encrypted by the mail server AMS with a secret key K of the mail server AMS from a receiver's identifier A, a sender's identifier B, and a nonce N issued by the mail server AMS, and sending the value {A, B, N}K to the sender via the mail server BMS; and    forming an e-mail address (LD address) by attaching a receiver's domain name to the encrypted value {A, B, N}K, and sending an e-mail to a receiver.    
   
   
       4 . An e-mail sending method, comprising the steps of: 
 disclosing a receiver's public address;    sending the public address and a message M B  for requesting a permission of communication with a sender to a receiver's mail server AMS via a sender's mail server BMS;    causing the mail server AMS to send the message M B  to a receiver;    causing the mail server AMS to receive an address issuance permission from the receiver who received and read the message; and    computing a value {{A, B, N}K} K BP  which is encrypted by the mail server AMS with a secret key K of the mail server AMS and is further encrypted with a sender's public key K BP  from a receiver's identifier A, a sender's identifier B, and a nonce N issued by the mail server AMS, and sending the value {{A, B, N}K} K BP  to the sender via the mail server BMS.    
   
   
       5 . An e-mail sending method, comprising the steps of: in a condition where a sender knows a receiver's e-mail address (LD address) with a receiver's domain name attached to a value {A, B, N}K which is encrypted by a mail server AMS with a secret key K, the secret key K being only possessed by the mail server AMS, from a receiver's identifier A, a sender's identifier B, and a nonce N issued by the mail server AMS, 
 causing a mail server BMS to receive the e-mail address and a message M from a sender;    causing the mail server BMS to send the e-mail address and the message M to the mail server AMS; and    causing the mail server AMS to identify a receiver from the e-mail address using a secret key Kin, and to send the message M to the receiver.    
   
   
       6 . An e-mail sending method comprising the steps of: in a condition where a sender knows a receiver's e-mail address (LD address) with a receiver's domain name attached to a value {A, B, N}K which is encrypted by a mail server AMS with a secret key K, the secret key K being only possessed by the mail server AMS, from a receiver's identifier A, a sender's identifier B, and a nonce N issued by the mail server AMS, 
 forming an e-mail address with a receiver's domain name attached to a value {{A, B, N}K AM , T}K AMP  which is encrypted with a receiver's public key from the encrypted value {A, B, N}K and a timestamp T, and sending a message M;    causing the mail server BMS to send a message M to the mail server AMS using the e-mail address; and    causing the mail server AMS to identify a receiver using a public key K AMP , a secret key K AM , and a secret key K AMS  of the mail server AMS and to send a message M to the receiver.    
   
   
       7 . The method according to  claim 6 , when the timestamp T is earlier than a time in which a validity period L is subtracted from a current time, further comprising at least one step taken from a group of steps consisting of: 
 precluding the message M from being sent to the receiver; or    notifying the receiver that the timestamp is old.    
   
   
       8 . An e-mail sending method, comprising the steps of: 
 causing a receiver's mailer AML to set a receiver's e-mail address in a sender's field and to send an e-mail to a mail server AMS, in response to inputting of a sender's address in a destination field of the receiver's mailer AML;    generating an e-mail address (LD address) with a receiver's domain name attached to a value {A, B, N}K which is encrypted by a mail server AMS with a secret key K, the secret key K being only possessed by the mail server AMS, from a receiver's identifier A, a sender's identifier B, and a nonce N issued by the mail server AMS, and rewriting the sender's field to be filled in with the LD address;    causing the mail server AMS, in response to any one of creating of a user extension field by a mail server AMS and creating of a user extension field by a receiver, to write a receiver's alias in the user extension field;    causing the mail server AMS to send an e-mail having the user extension field to a mail server BMS;    causing the mail server BMS to send an e-mail to a sender;    causing a sender's mailer BML to receive the sent e-mail;    causing the sender's mailer BML to recognize the user extension field, and to create a table having the contents of the user extension field regarded as a key and the contents of the sender's field regarded as a value; and    causing the sender's mailer BML to rewrite the sender's field to be filled in with the contents of the user extension field, and to show the rewritten contents to a user.    
   
   
       9 . The method according to  claim 8 , upon sending an e-mail from the sender to the receiver, further comprising the steps of: 
 finding a value corresponding to the receiver'se-mail address, which is inputted in the destination field, with reference to the table;    overwriting the value on the destination field; and    sending the e-mail to the mail server BMS.    
   
   
       10 . The method according to  claim 2 , further comprising the steps of: 
 sending an e-mail to the receiver from a third person by use of the LD address of which the sender notified the receiver;    causing a mail server CMS of the third person to send the e-mail to the mail server AMS;    causing the mail server AMS to decrypt an account part of the e-mail; and    determining whether or not information in the sender's field of the e-mail coincides with information obtained due to the decoding by comparing both of the information.    
   
   
       11 . The method according to  claim 10 , further comprising any one of the steps of: when a result of the comparison is not coincident, and then the third person is determined not to be an authorized e-mail sender, 
 disabling the LD address;    precluding the e-mail from being sent to the receiver; and    issuing a warning notification to the receiver.    
   
   
       12 . An e-mail address forming system comprising: 
 means for sending a receiver's identifier A and a sender's identifier B to a receiver's mail server AMS;    means for computing a value {A, B, N}K which is encrypted by the mail server AMS with a secret key K, the secret key K being only possessed by the mail server AMS, from the receiver's identifier A, the sender's identifier B, and a nonce N issued by the mail server AMS, and for sending the value {A, B, N}K to a receiver; and    means for forming an e-mail address (LD address) to be used by a sender who sends an e-mail to a receiver, by attaching a receiver's domain name to the encrypted value {A, B, N}K.    
   
   
       13 . A mail system for sending an e-mail from a sender to a receiver, comprising: 
 means for sending a receiver's identifier A and a sender's identifier B to a receiver's mail server AMS;    means for computing a value {A, B, N}K which is encrypted by the mail server AMS with a secret key K, the secret key K being only possessed by the mail server AMS, from the receiver's identifier A, the sender's identifier B, and a nonce N issued by the mail server AMS, and for sending the value {A, B, N}K to a receiver;    means for forming an e-mail address (LD address) to be used by a sender who sends an e-mail to a receiver, by attaching a receiver's domain name to the encrypted value {A, B, N}K; and    means for sending the formed e-mail address to the sender.    
   
   
       14 . A mail system comprising: 
 means for disclosing a receiver's public address;    means for sending the public address and a message M B  for requesting a permission of communication with a sender to a receiver's mail server AMS via a sender's mail server BMS;    means for causing the mail server AMS to send the message M B  to a receiver;    means for causing the mail server AMS to receive an address issuance permission from the receiver who received and read the message;    means for computing a value {A, B, N}K which is encrypted by the mail server AMS with a secret key K of the mail server AMS from a receiver's identifier A, a sender's identifier B, and a nonce N issued by the mail server AMS, and for sending the value {A, B, N}K to the sender via the mail server BMS; and    means for forming an email address (LD address) by attaching a receiver's domain name to the encrypted value {A, B, N}K, and for sending an e-mail to a receiver.    
   
   
       15 . A mail system comprising: 
 means for disclosing a receiver's public address;    means for sending the public address and a message M B  for requesting a permission of communication with a sender to a receiver's mail server AMS via a sender's mail server BMS;    means for causing the mail server AMS to send the message M B  to a receiver;    means for causing the mail server AMS to receive an address issuance permission from the receiver who received and read the message; and    means for computing a value {{A, B, N}K} K BP  which is encrypted by the mail server AMS with a secret key K of the mail server AMS and is further encrypted with a sender's public key K BP  from a receiver's identifier A, a sender's identifier B, and a nonce N issued by the mail server AMS, and for sending the value {{A, B, N}K} K BP  to the sender via the mail server BMS.    
   
   
       16 . A mail system comprising: in a condition where a sender knows a receiver's e-mail address (LD address) with a receiver's domain name attached to a value {A, B, N}K which is encrypted by a mail server AMS with a secret key K, the secret key K being only possessed by the mail server AMS, from a receiver's identifier A, a sender's identifier B, and a nonce N issued by the mail server AMS, means for causing a mail server BMS to receive the e-mail address and a message M from a sender; 
 means for causing the mail server BMS to send the e-mail address and the message M to the mail server AMS; and    means for causing the mail server AMS to identify a receiver from the e-mail address using a secret key K AM , and to send the message M to the receiver.    
   
   
       17 . A mail system comprising: in a condition where a sender knows a receiver's e-mail address (LD address) with a receiver's domain name attached to a value {A, B, N}K which is encrypted by a mail server AMS with a secret key K, the secret key K being only possessed by the mail server AMS, from a receiver's identifier A, a sender's identifier B, and a nonce N issued by the mail server AMS, means for forming an e-mail address with a receiver's domain name attached to a value {{A, B, N}K AM , T}K AMP  which is encrypted with a receiver's public key from the encrypted value {A, B, N}K and a timestamp T, and for sending a message M; 
 means for causing the mail server BMS to send a message M to the mail server AMS using the e-mail address; and    means for causing the mail server AMS to identify a receiver using a public key K AMP , a secret key K AM , and a secret key K AMS  of the mail server AMS and to send a message M to the receiver.    
   
   
       18 . The system according to  claim 17 , when the timestamp T is earlier than a time in which a validity period L is subtracted from a current time, further comprising at least one step taken from a group of steps consisting of: 
 precluding the message M from being sent to the receiver; or notifying the receiver that the timestamp is old.    
   
   
       19 . A mail system comprising: 
 means for causing a receiver's mailer AML to set a receiver's e-mail address in a sender's field and to send an e-mail to a mail server AMS in response to inputting of a sender's address in a destination field of the receiver's mailer AML;    means for generating an e-mail address (LD address) with a receiver's domain name attached to a value {A, B, N}K which is encrypted by a mail server AMS with a secret key K, the secret key K being only possessed by the mail server AMS, from a receiver's identifier A, a sender's identifier B, and a nonce N issued by the mail server AMS, and for rewriting the sender's field to be filled in with the LD address;    means for causing the mail server AMS, in response to any one of creating of a user extension field by a mail server AMS and creating of a user extension field by a receiver, to write a receiver's alias in the user extension field;    means for causing the mail server AMS to send an e-mail having the user extension field to a mail server BMS;    means for causing the mail server BMS to send an e-mail to a sender;    means for causing a sender's mailer BML to receive the e-mail having been sent;    means for causing the sender's mailer BML to recognize the user extension field, and to create a table having the contents of the user extension field regarded as a key and the contents of the sender's field regarded as a value; and    means for causing the sender's mailer BML to rewrite the sender's field to be filled in with the contents of the user extension field, and to show the rewritten contents to a user.    
   
   
       20 . The system according to  claim 19 , when the mail system sends an e-mail from the sender to the receiver, further comprising the steps of: 
 finding a value corresponding to the receiver's e-mail address, which is inputted in the destination field, with reference to the table;    overwriting the value on the destination field; and    sending the e-mail to the mail server BMS.    
   
   
       21 . The system according to  claim 12 , further comprising: 
 means for sending an e-mail to the receiver from a third person by use of the LD address of the receiver which the sender notified the third person;    means for sending the e-mail to the mail server AMS from a mail server CMS of the third person;    means for decoding an account part of the e-mail by use of the mail server AMS; and    means for determining whether or not information in the sender's field of the e-mail coincides with information obtained due to the decoding by comparing both of the information.    
   
   
       22 . The system according to  claim 21 , further comprising: 
 means for disabling the LD address, precluding the e-mail from being sent to the receiver, or issuing a warning notification to the receiver when a result of the comparison is not coincident, and then the third person is determined not to be an authorized e-mail sender.    
   
   
       23 . An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein for causing formation of an e-mail address, the computer readable program code means in said article of manufacture comprising computer readable program code means for causing a computer to effect the steps of  claim 1 .  
   
   
       24 . A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for sending e-mail, said method steps comprising the steps of  claim 2 .  
   
   
       25 . A computer program product comprising a computer usable medium having computer readable program code means embodied therein for causing functions of an e-mail address forming system, the computer readable program code means in said computer program product comprising computer readable program code means for causing a computer to effect the functions of  claim 12 .  
   
   
       26 . A computer program product comprising a computer usable medium having computer readable program code means embodied therein for causing functions of a mail system for sending an e-mail from a sender to a receiver, the computer readable program code means in said computer program product comprising computer readable program code means for causing a computer to effect the functions of  claim 13.