-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 I can't tell you how many conversations I've had lately with laypeople and journalists who have tried to get up to speed with PGP and just can't manage it... they inevitably ask me if there is a way to encrypt email such that they have to know nothing or little to us it. I have to tell them, not really. This seems to be getting in that direction! So, thank you, for working on this... I do wish the delimiter were something other than "?", but I'm not sure if there are any other design choices.
best, Joe On Tue Oct 15 13:26:46 2013, Phillip Hallam-Baker wrote: > This is how the scheme works in practice. > > > > Private Key Example > > Alice uses a key generation tool to generate a public keypair. The > public parameters in hexadecimal are: > > Modulus : a4 11 df 43 4a 6b a1 3e 29 78 5e 65 3c 3e 77 71 78 e5 be > bf 1e aa cd 4b 07 94 78 05 c6 c8 06 52 a6 32 ce 8d 31 88 43 f5 78 > b4 17 03 99 b1 1b a4 fc e9 82 ec d7 10 f2 56 f4 dc b8 0e e4 d2 e9 > e8 ad 90 41 e6 9a 65 ad 97 c3 a6 f4 49 51 b2 cb 98 4c d9 19 ba b4 > b6 06 7c 87 79 3f 30 01 fa 1d d9 5c ad 94 f6 5e 09 2d 32 5f 1d f7 > ce d2 f5 d1 68 05 c6 95 2b 9a c3 f5 f4 8a f2 a1 a6 9d 7a de 93 > Exponent : 01 00 01 > > The Key Identifier is calculated using SHA512 and truncated to 224 > bits to produce the Key Identifier value. The Key Identifier in > Base32 encoding is: > > KeyIdentifier: > ABAFYA-ATQBAB-UAG4VXA-MMACY7-4AMIAB4-NWALTA-GSHYAK-5AA > > An email sender may send email to Alice through a compliant gateway > as follows: [email protected] Send email to Alice using encryption > if and only if an encryption key for Alice can be found and Alice > has published the email encryption policy 'encryption preferred' or > stronger. ? [email protected] Send email to Alice using encryption > if and only if an encryption key for Alice can be found, otherwise > report an error. > ABAFYA-ATQBAB-UAG4VXA-MMACY7-4AMIAB4-NWALTA-GSHYAK-5AA?al...@example.com > Send email to Alice using encryption if and only if an encryption > key for Alice can be found that is directly endorsed under the > specified key, otherwise report an error. > ABAFYA-ATQBAB-UAG4VXA-MMACY7-4AMIAB4-NWALTA-GSHYAK-5AA?? > [email protected] Send email to Alice using encryption if and only > if an encryption key for Alice can be found that is (directly or > indierectly) endorsed under the specified key, otherwise report an > error. > > The key identifiers are 224 bits long plus an 8 bit prefix to > specify the algorithm. It might well be desirable to trim them back > to 160 bits but certainly no less than 128 bits. > > Here is 160 bits: > [email protected] > > Here is 128 bits: [email protected] > > > The 128 bit key identifier might be strong enough for a personal > key identifier since the difficulty of finding a key that would > match by brute force would be 128 bits. > > For an organizational key, there is a risk of the key being formed > maliciously so as to evade transparency requirements and so the > longer identifier is 'probably' necessary. > > > > This is how the scheme works in practice. > > > > Private Key Example > > Alice uses a key generation tool to generate a public keypair. The > public parameters in hexadecimal are: > > Modulus : a4 11 df 43 4a 6b a1 3e 29 78 5e 65 3c 3e 77 71 78 e5 be > bf 1e aa cd 4b 07 94 78 05 c6 c8 06 52 a6 32 ce 8d 31 88 43 f5 78 > b4 17 03 99 b1 1b a4 fc e9 82 ec d7 10 f2 56 f4 dc b8 0e e4 d2 e9 > e8 ad 90 41 e6 9a 65 ad 97 c3 a6 f4 49 51 b2 cb 98 4c d9 19 ba b4 > b6 06 7c 87 79 3f 30 01 fa 1d d9 5c ad 94 f6 5e 09 2d 32 5f 1d f7 > ce d2 f5 d1 68 05 c6 95 2b 9a c3 f5 f4 8a f2 a1 a6 9d 7a de 93 > Exponent : 01 00 01 The Key Identifier is calculated using SHA512 > and truncated to 224 bits to produce the Key Identifier value. The > Key Identifier in Base32 encoding is: KeyIdentifier: > ABAFYA-ATQBAB-UAG4VXA-MMACY7-4AMIAB4-NWALTA-GSHYAK-5AA An email > sender may send email to Alice through a compliant gateway as > follows: > > [email protected] <mailto:[email protected]> Send email to Alice > using encryption if and only if an encryption key for Alice can be > found and Alice has published the email encryption policy > 'encryption preferred' or stronger. [email protected] > <mailto:[email protected]> Send email to Alice using encryption if > and only if an encryption key for Alice can be found, otherwise > report an error. > ABAFYA-ATQBAB-UAG4VXA-MMACY7-4AMIAB4-NWALTA-GSHYAK-5AA?al...@example.com > > <mailto:[email protected]> > Send email to Alice using encryption if and only if an encryption > key for Alice can be found that is directly endorsed under the > specified key, otherwise report an error. > ABAFYA-ATQBAB-UAG4VXA-MMACY7-4AMIAB4-NWALTA-GSHYAK-5AA??al...@example.com > > <mailto:[email protected]> > Send email to Alice using encryption if and only if an encryption > key for Alice can be found that is (directly or indierectly) > endorsed under the specified key, otherwise report an error. > > > The key identifiers are 224 bits long plus an 8 bit prefix to > specify the algorithm. It might well be desirable to trim them back > to 160 bits but certainly no less than 128 bits. > > Here is 160 bits: > [email protected] > <mailto:[email protected]> > > Here is 128 bits: [email protected] > <mailto:[email protected]> > > > The 128 bit key identifier might be strong enough for a personal > key identifier since the difficulty of finding a key that would > match by brute force would be 128 bits. > > For an organizational key, there is a risk of the key being formed > maliciously so as to evade transparency requirements and so the > longer identifier is 'probably' necessary. > > -- Website: http://hallambaker.com/ > > > _______________________________________________ perpass mailing > list [email protected] > https://www.ietf.org/mailman/listinfo/perpass - -- Joseph Lorenzo Hall Senior Staff Technologist Center for Democracy & Technology 1634 I ST NW STE 1100 Washington DC 20006-4011 (p) 202-407-8825 (f) 202-637-0968 [email protected] PGP: https://josephhall.org/gpg-key fingerprint: BE7E A889 7742 8773 301B 4FA1 C0E2 6D90 F257 77F8 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.13 (Darwin) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEAREIAAYFAlJephsACgkQwOJtkPJXd/i1FACfczzEWerNIIy3Xau7yn28pQzf R3YAn1+UeV5yFzq1YqXQHA5Wy1Sje4By =2w2c -----END PGP SIGNATURE----- _______________________________________________ perpass mailing list [email protected] https://www.ietf.org/mailman/listinfo/perpass
