Old vs New packet format (PGPainless?)

[tomholub]

browser

-----BEGIN PGP MESSAGE-----
Version: FlowCrypt Email Encryption 8.2.4
Comment: Seamlessly send and receive encrypted email
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=s2Yp
-----END PGP MESSAGE-----

versus Android:

-----BEGIN PGP MESSAGE-----
Version: PGPainless

hF4DE4nP38Il0h4SAQdAJ5dE6kNrIMw5/kOSkdKw+vvJrRG559/TuM4wyid5gzQw
pAWc7OKtYYrwTiDXKvR2PwiivQwteXz4P1cWDKLr2yXugJ6cozM0F4hro0/yiOiK
0rsBXFgjiFDgSTP0LeZli+MrU0mt9jFxCsnylWr9/dJmEmvjI96KpBX4U2np9TUD
NDH+5+WSoxoRlFKDNDT8gOjUM+zPyjSNc8xf3IVmoVUDjdnSdR41p1dWp+vgxF5R
zPXqKkijCqzyOh0/Y8Spjas21Ha+M6NQIcANaunzGshb05Cz1L4Ptg//0LuZ+Yaz
SRkcIU2SzNBmtBF6Q/q/PFnA9CJEmAAHG56tRho/944KWaPCa/54/hYK/Vb6
=dZvv
-----END PGP MESSAGE-----

browser

New: Public-Key Encrypted Session Key Packet(tag 1)(94 bytes)
	New version(3)
	Key ID - 0x1389CFDFC225D21E
	Pub alg - Reserved for Elliptic Curve(pub 18)
		unknown(pub 18)
		-> m = sym alg(1 byte) + checksum(2 bytes) + PKCS-1 block type 02
New: Symmetrically Encrypted and MDC Packet(tag 18)(661 bytes)
	Ver 1
	Encrypted data [sym alg is specified in pub-key encrypted session key]
		(plain text + MDC SHA1(20 bytes))

android:

Old: Public-Key Encrypted Session Key Packet(tag 1)(94 bytes)
	New version(3)
	Key ID - 0x1389CFDFC225D21E
	Pub alg - Reserved for Elliptic Curve(pub 18)
		unknown(pub 18)
		-> m = sym alg(1 byte) + checksum(2 bytes) + PKCS-1 block type 02
New: Symmetrically Encrypted and MDC Packet(tag 18)(187 bytes)
	Ver 1
	Encrypted data [sym alg is specified in pub-key encrypted session key]
		(plain text + MDC SHA1(20 bytes))

Originally posted by @tomholub in #1667 (comment)

[tomholub]

The browser uses New (presumably packet format) but Android uses Old per pgpdump.

@vanitasvitae could you please look into the difference in format?

[vanitasvitae]

This is BC still using the old format for PKESK packets. I will see if I can upstream a fix.

[vanitasvitae]

I had opened an issue about this quite some time ago on the BC issue tracker (see bcgit/bc-java#1010).
I left another comment asking in whether they are interested in a patch for this.

For you it should not matter too much, since the old packet format is still required to be supported by implementations (this will change in the upcoming spec revision).

[vanitasvitae]

One argument pro the new packet format is that it will be a MUST in the upcoming revision of rfc4880.