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copied!<p>When you generate a signature packet, it's always a signature <em>of</em> something <em>by</em> someone. That is, there's some blob of data being signed, and a public key, and the point of a signature is that it's something that's only supposed to be able to be made by someone who has that exact data and the corresponding private key.</p> <p>So "the data being signed" will be whatever that blob of data happens to be. See section 5.2.1 of RFC4880 for some examples. In the present case, presumably you're interested in the signature packets inside your public key block.</p> <p>The first one is a "Positive certification of a User ID and Public Key packet(0x13)". This is described in section 5.2.4 of RFC4880.</p> <p>The second one is a "subkey binding signature", whereby the primary key (the DSA one) guarantees that the subkey (ElGamal encrypt-only) belongs to it. The way this works is also described in section 5.2.4 of RFC4880.</p> <p>Here's the relevant text from 5.2.4:</p> <blockquote> <p>When a signature is made over a key, the hash data starts with the octet 0x99, followed by a two-octet length of the key, and then body of the key packet. (Note that this is an old-style packet header for a key packet with two-octet length.) A subkey binding signature (type 0x18) or primary key binding signature (type 0x19) then hashes the subkey using the same format as the main key (also using 0x99 as the first octet). Key revocation signatures (types 0x20 and 0x28) hash only the key being revoked.</p> </blockquote> <p>and then</p> <blockquote> <p>A certification signature (type 0x10 through 0x13) hashes the User ID being bound to the key into the hash context after the above data. A V3 certification hashes the contents of the User ID or attribute packet packet, without any header. A V4 certification hashes the constant 0xB4 for User ID certifications or the constant 0xD1 for User Attribute certifications, followed by a four-octet number giving the length of the User ID or User Attribute data, and then the User ID or User Attribute data.</p> </blockquote>

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