git/gpg-interface.h

#ifndef GPG_INTERFACE_H
#define GPG_INTERFACE_H

#define GPG_VERIFY_VERBOSE		1
#define GPG_VERIFY_RAW			2
#define GPG_VERIFY_OMIT_STATUS	4

struct signature_check {
	char *payload;
	char *gpg_output;
	char *gpg_status;

	/*
	 * possible "result":
	 * 0 (not checked)
	 * N (checked but no further result)
	 * U (untrusted good)
	 * G (good)
	 * B (bad)
	 */
	char result;
	char *signer;
	char *key;
};

void signature_check_clear(struct signature_check *sigc);

/*
 * Look at GPG signed content (e.g. a signed tag object), whose
 * payload is followed by a detached signature on it.  Return the
 * offset where the embedded detached signature begins, or the end of
 * the data when there is no such signature.
 */
size_t parse_signature(const char *buf, size_t size);

/*
 * Create a detached signature for the contents of "buffer" and append
 * it after "signature"; "buffer" and "signature" can be the same
 * strbuf instance, which would cause the detached signature appended
 * at the end.
 */
int sign_buffer(struct strbuf *buffer, struct strbuf *signature,
		const char *signing_key);

/*
 * Run "gpg" to see if the payload matches the detached signature.
 * gpg_output, when set, receives the diagnostic output from GPG.
 * gpg_status, when set, receives the status output from GPG.
 */
int verify_signed_buffer(const char *payload, size_t payload_size,
			 const char *signature, size_t signature_size,
			 struct strbuf *gpg_output, struct strbuf *gpg_status);

int git_gpg_config(const char *, const char *, void *);
void set_signing_key(const char *);
const char *get_signing_key(void);
int check_signature(const char *payload, size_t plen,
		    const char *signature, size_t slen,
		    struct signature_check *sigc);
void print_signature_buffer(const struct signature_check *sigc,
			    unsigned flags);

#endif