g10: Add openpgp_protected flag to agent secret key export functions

* g10/call-agent.c, g10/call-agent.h (agent_export_key): Add
openpgp_protected flag.
* g10/export.c (receive_seckey_from_agent): Request openpgp_protected
secret keys from agent.
* agent/command.c (hlp_export_key): EXPORT_KEY help text: add a
brief description of the effect of --openpgp.
--

The --openpgp flag for gpg-agent's EXPORT_KEY actually forces
encryption in a certain (RFC 4880-compatible format).  This changeset
exposes that functionality in internal functions, and clarifies
functionality in the agent's help text.

Signed-off-by: Daniel Kahn Gillmor <[email protected]>

1 files changed, 9 insertions, 6 deletions

diff --git a/g10/call-agent.c b/g10/call-agent.c
index 470fa168c..06a2d8678 100644
--- a/g10/call-agent.c
+++ b/g10/call-agent.c
@@ -2315,13 +2315,15 @@ agent_import_key (ctrl_t ctrl, const char *desc, char **cache_nonce_addr,
 
 /* Receive a secret key from the agent.  HEXKEYGRIP is the hexified
    keygrip, DESC a prompt to be displayed with the agent's passphrase
-   question (needs to be plus+percent escaped).  If CACHE_NONCE_ADDR
-   is not NULL the agent is advised to first try a passphrase
-   associated with that nonce.  On success the key is stored as a
-   canonical S-expression at R_RESULT and R_RESULTLEN.  */
+   question (needs to be plus+percent escaped).  if OPENPGP_PROTECTED
+   is not zero, ensure that the key material is returned in RFC
+   4880-compatible passphrased-protected form.  If CACHE_NONCE_ADDR is
+   not NULL the agent is advised to first try a passphrase associated
+   with that nonce.  On success the key is stored as a canonical
+   S-expression at R_RESULT and R_RESULTLEN.  */
 gpg_error_t
 agent_export_key (ctrl_t ctrl, const char *hexkeygrip, const char *desc,
-                  char **cache_nonce_addr,
+                  int openpgp_protected, char **cache_nonce_addr,
                   unsigned char **r_result, size_t *r_resultlen)
 {
   gpg_error_t err;
@@ -2351,7 +2353,8 @@ agent_export_key (ctrl_t ctrl, const char *hexkeygrip, const char *desc,
         return err;
     }
 
-  snprintf (line, DIM(line)-1, "EXPORT_KEY --openpgp %s%s %s",
+  snprintf (line, DIM(line)-1, "EXPORT_KEY %s%s%s %s",
+            openpgp_protected ? "--openpgp ":"",
             cache_nonce_addr && *cache_nonce_addr? "--cache-nonce=":"",
             cache_nonce_addr && *cache_nonce_addr? *cache_nonce_addr:"",
             hexkeygrip);