The encryption key could be derived from the decryption key as easily as vice versa.

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When the recipient opens the e-mail, the message retrieves the decryption key from Disappearing's key server and it's displayed in decrypted form.

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Mullenweg countered with the fact that all Web applications must either store their database credentials in plain text or keep a plaintext decryption key around somewhere.

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Each file will then be issued a unique, sophisticated decryption key which only the file holder will control, allowing them to share the file as they choose.

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But after the time limit specified by the sender, the decryption key is erased from Disappearing's key server, making the message unreadable and effectively destroying it, even if the recipient stored it.

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If these card numbers were in fact stolen from the Playstation Network, it may be that the encryption Sony says it used was weak, badly implemented, or that the decryption key was included in the stolen data.

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He could run a special decryption program in a different part of the machine, and make the key appear there.

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