* guix/pk-crypto.scm (string->canonical-sexp, sign, generate-key): Pass
the procedure name as the first argument to 'throw'.
(gcrypt-error-printer): New procedure.
<top level>: Add call to 'set-exception-printer!'.
* guix/nar.scm (restore-one-item): Add 'proc' parameter to 'catch'
handler for 'gcry-error.
* guix/scripts/archive.scm (%options, generate-key-pair, authorize-key):
Likewise.
* guix/scripts/substitute-binary.scm (narinfo-signature->canonical-sexp):
Likewise.
* guix/pki.scm (write-acl): New procedure.
(ensure-acl): Use it. Fixes a regression introduced in 39831f1,
whereby 'ensure-acl' would yield a wrong-type-arg error.
* guix/scripts/archive.scm (authorize-key): Use 'write-acl'.
* guix/pki.scm (acl-entry-sexp, acl-sexp): Remove.
(public-keys->acl, current-acl): Return a native sexp.
(acl->public-keys, authorized-key?): Expect ACL to be a native sexp.
* guix/scripts/archive.scm (authorize-key): Convert ACL to
canonical-sexp when writing it.
* guix/pk-crypto.scm (gcrypt-version): New procedure.
* guix/scripts/archive.scm (%key-generation-parameters): New variable.
(%options) <generate-key>: Use it.
* tests/pk-crypto.scm ("sign + verify, Ed25519"): Skip if using gcrypt < 1.6.0.
* guix/pki.scm (ensure-acl): Make sure the directory of %ACL-FILE
exists.
* guix/scripts/archive.scm (generate-key-pair): Likewise for
%PUBLIC-KEY-FILE.
* guix/scripts/archive.scm (authorize-key): New procedure.
(guix-archive): Call it when OPTS contains 'authorize-key'.
* tests/guix-archive.sh: Add test with invalid public key.
* guix/pki.scm: Export '%acl-file'.
* doc/guix.texi (Invoking guix archive): Make it clear that '--import'
works only with authorized keys. Document '--authorize'.
