14.11.2016 16:00, John R Levine пишет: > > Bonus hack for BCC users: instead of putting the recipients into the > r= tag, put in colon separated hex or base32 MD5 hashes of the > recipients. To avoid rainbow table attacks, the new rs= tag includes > a variable length random salt string that is prefixed to each address > before hashing. So to verify the signature, salt and hash the actual > recipients and see if all the hashes are in the r= list. This leaks > the number of recipients but not their addresses.
It doesn't protect against BCC discovery. If Alice al...@example.com wants to check Bob bob@example is a recipients of Bcc, she can directly get a hash of Bob's address with salt without the need to use any rainbow tables. Asymmetric cryptography is requires with both sender's and recipient's key to avoid this possibility. -- Vladimir Dubrovin @Mail.Ru
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