scripts: imgtool: Add command to dump private keys
This applies a few improvements to a commit previously included in
PR #596:
* Move functions to dump a private key to the private key classes
* Remove language option; always dumps in C format
* Add option to generate a minimal dump. This will remove extra
parameters that are present in keys generated with the `keygen`
command.
For P256 this will remove the public point, which is already
ignored by the parsing function. The resulting key dump shrinks
from 138 to 70 bytes.
For RSA it will remove the DP/DQ/QP parameters which are only
used with CRT enabled, and if not available, can be calculated at
runtime. This reduces the size of a key dump from around 1190
bytes to somewhere close to 800 bytes. A patch to the RSA parsing
routine will be added in another commit.
Signed-off-by: Fabio Utzig <utzig@apache.org>
Signed-off-by: Ioannis Konstantelias <ikonstadel@gmail.com>
diff --git a/scripts/imgtool/main.py b/scripts/imgtool/main.py
index 2c1e049..61ed282 100755
--- a/scripts/imgtool/main.py
+++ b/scripts/imgtool/main.py
@@ -92,19 +92,33 @@
@click.option('-l', '--lang', metavar='lang', default=valid_langs[0],
type=click.Choice(valid_langs))
@click.option('-k', '--key', metavar='filename', required=True)
-@click.command(help='Get public key from keypair')
+@click.command(help='Dump public key from keypair')
def getpub(key, lang):
key = load_key(key)
if key is None:
print("Invalid passphrase")
elif lang == 'c':
- key.emit_c()
+ key.emit_c_public()
elif lang == 'rust':
- key.emit_rust()
+ key.emit_rust_public()
else:
raise ValueError("BUG: should never get here!")
+@click.option('--minimal', default=False, is_flag=True,
+ help='Reduce the size of the dumped private key to include only '
+ 'the minimum amount of data required to decrypt. This '
+ 'might require changes to the build config. Check the docs!'
+ )
+@click.option('-k', '--key', metavar='filename', required=True)
+@click.command(help='Dump private key from keypair')
+def getpriv(key, minimal):
+ key = load_key(key)
+ if key is None:
+ print("Invalid passphrase")
+ key.emit_private(minimal)
+
+
@click.argument('imgfile')
@click.option('-k', '--key', metavar='filename')
@click.command(help="Check that signed image can be verified by given key")
@@ -271,6 +285,7 @@
imgtool.add_command(keygen)
imgtool.add_command(getpub)
+imgtool.add_command(getpriv)
imgtool.add_command(verify)
imgtool.add_command(sign)
imgtool.add_command(version)