Re: [PATCH 04/16] PGP: Add definitions (RFC 4880) and packet parser[ver #2]

[Ben Hutchings]

On Tue, 2011-11-29 at 23:43 +0000, David Howells wrote:
> Add some useful PGP definitions from RFC 4880.  These describe details of
> public key crypto as used by crypto keys for things like signature
> verification.
[...]
> +struct pgp_signature_v3_packet {
> +	enum pgp_signature_version version : 8; /* == PGP_SIG_VERSION_3 */
> +	u8	length_of_hashed;	/* == 5 */
> +	struct {
> +		enum pgp_signature_type signature_type : 8;
> +		struct pgp_time	creation_time;
> +	} hashed;
> +	struct pgp_key_ID issuer;
> +	enum pgp_pubkey_algo pubkey_algo : 8;
> +	enum pgp_hash_algo hash_algo : 8;
> +};
> +
> +struct pgp_signature_v4_packet {
> +	enum pgp_signature_version version : 8;	/* == PGP_SIG_VERSION_4 */
> +	enum pgp_signature_type signature_type : 8;
> +	enum pgp_pubkey_algo pubkey_algo : 8;
> +	enum pgp_hash_algo hash_algo : 8;
> +};
[...]
> +struct pgp_key_v3_packet {
> +	enum pgp_key_version version : 8;
> +	struct pgp_time	creation_time;
> +	u8 expiry[2];				/* 0 or time in days till expiry */
> +	enum pgp_pubkey_algo pubkey_algo : 8;
> +	u8 key_material[0];
> +};
> +
> +struct pgp_key_v4_packet {
> +	enum pgp_key_version version : 8;
> +	struct pgp_time	creation_time;
> +	enum pgp_pubkey_algo pubkey_algo : 8;
> +	u8 key_material[0];
> +};
[...]

I'm a little uneasy about these structure definitions.  There have been
C ABIs that set the structure alignment to at least 4 by default.  It
may be better to play safe by declaring them '__packed'.

Ben.

-- 
Ben Hutchings
Klipstein's 4th Law of Prototyping and Production:
                                    A fail-safe circuit will destroy others.

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