imgtool: Fix getpriv error return with private key

[Roolli]

Fixes #1746

[davidvincze]

I've manually tested imgtool's getpriv, getpub, keygen and sign, verify options for both ec-p256 and ec-p384 keys.
The fix looks good to me, it was just a method resolution order issue.

[davidvincze]

@nordicjm may I ask you to review @Roolli's fix? Thank you.

[nordicjm]

Not working.
Old:

imgtool getpub -k enc-ec256-pub.pem 
/* Autogenerated by imgtool.py, do not edit. */
const unsigned char ecdsa_pub_key[] = {
    0x30, 0x59, 0x30, 0x13, 0x06, 0x07, 0x2a, 0x86,
    0x48, 0xce, 0x3d, 0x02, 0x01, 0x06, 0x08, 0x2a,
    0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07, 0x03,
    0x42, 0x00, 0x04, 0x8a, 0x44, 0x73, 0x00, 0x94,
    0xc9, 0x80, 0x27, 0x31, 0x0d, 0x23, 0x36, 0x6b,
    0xe9, 0x69, 0x9f, 0xcb, 0xc5, 0x7c, 0xc8, 0x44,
    0x1a, 0x93, 0xe6, 0xee, 0x7d, 0x86, 0xa6, 0xae,
    0x5e, 0x93, 0x72, 0x74, 0xd9, 0xe1, 0x5a, 0x1c,
    0x9b, 0x65, 0x1a, 0x2b, 0x61, 0x41, 0x28, 0x02,
    0x73, 0x84, 0x12, 0x97, 0x3a, 0x2d, 0xa2, 0xa0,
    0x67, 0x77, 0x02, 0xda, 0x67, 0x1a, 0x4b, 0xdd,
    0xd7, 0x71, 0xcc,
};
const unsigned int ecdsa_pub_key_len = 91;

With this:

python ./scripts/imgtool.py getpub -k enc-ec256-pub.pem > 2
Traceback (most recent call last):
  File "/tmp/qq/mcuboot/./scripts/imgtool.py", line 22, in <module>
    main.imgtool()
  File "/usr/lib/python3.11/site-packages/click/core.py", line 1130, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/site-packages/click/core.py", line 1055, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/site-packages/click/core.py", line 1657, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/site-packages/click/core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/site-packages/click/core.py", line 760, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/qq/mcuboot/scripts/imgtool/main.py", line 144, in getpub
    key.emit_c_public()
  File "/tmp/qq/mcuboot/scripts/imgtool/keys/general.py", line 28, in emit_c_public
    encoded_bytes=self.get_public_bytes(),
                  ^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/qq/mcuboot/scripts/imgtool/keys/ecdsa.py", line 37, in get_public_bytes
    return self._get_public().public_bytes(
           ^^^^^^^^^^^^^^^^^^
  File "/tmp/qq/mcuboot/scripts/imgtool/keys/ecdsa.py", line 33, in _get_public
    return self.key.public_key()
           ^^^^^^^^^^^^^^^^^^^
AttributeError: '_EllipticCurvePublicKey' object has no attribute 'public_key'. Did you mean: 'public_bytes'?

[davidvincze]

Not working. Old:

imgtool getpub -k enc-ec256-pub.pem 
/* Autogenerated by imgtool.py, do not edit. */
const unsigned char ecdsa_pub_key[] = {
    0x30, 0x59, 0x30, 0x13, 0x06, 0x07, 0x2a, 0x86,
    0x48, 0xce, 0x3d, 0x02, 0x01, 0x06, 0x08, 0x2a,
    0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07, 0x03,
    0x42, 0x00, 0x04, 0x8a, 0x44, 0x73, 0x00, 0x94,
    0xc9, 0x80, 0x27, 0x31, 0x0d, 0x23, 0x36, 0x6b,
    0xe9, 0x69, 0x9f, 0xcb, 0xc5, 0x7c, 0xc8, 0x44,
    0x1a, 0x93, 0xe6, 0xee, 0x7d, 0x86, 0xa6, 0xae,
    0x5e, 0x93, 0x72, 0x74, 0xd9, 0xe1, 0x5a, 0x1c,
    0x9b, 0x65, 0x1a, 0x2b, 0x61, 0x41, 0x28, 0x02,
    0x73, 0x84, 0x12, 0x97, 0x3a, 0x2d, 0xa2, 0xa0,
    0x67, 0x77, 0x02, 0xda, 0x67, 0x1a, 0x4b, 0xdd,
    0xd7, 0x71, 0xcc,
};
const unsigned int ecdsa_pub_key_len = 91;

With this:

python ./scripts/imgtool.py getpub -k enc-ec256-pub.pem > 2
Traceback (most recent call last):
  File "/tmp/qq/mcuboot/./scripts/imgtool.py", line 22, in <module>
    main.imgtool()
  File "/usr/lib/python3.11/site-packages/click/core.py", line 1130, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/site-packages/click/core.py", line 1055, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/site-packages/click/core.py", line 1657, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/site-packages/click/core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/site-packages/click/core.py", line 760, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/qq/mcuboot/scripts/imgtool/main.py", line 144, in getpub
    key.emit_c_public()
  File "/tmp/qq/mcuboot/scripts/imgtool/keys/general.py", line 28, in emit_c_public
    encoded_bytes=self.get_public_bytes(),
                  ^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/qq/mcuboot/scripts/imgtool/keys/ecdsa.py", line 37, in get_public_bytes
    return self._get_public().public_bytes(
           ^^^^^^^^^^^^^^^^^^
  File "/tmp/qq/mcuboot/scripts/imgtool/keys/ecdsa.py", line 33, in _get_public
    return self.key.public_key()
           ^^^^^^^^^^^^^^^^^^^
AttributeError: '_EllipticCurvePublicKey' object has no attribute 'public_key'. Did you mean: 'public_bytes'?

I haven't tested it with the enc-* keys, only the ones that are used for signing, sorry. @Roolli could you have a look at it, please?

[davidvincze]

Please fix the issue with public key objects.

[davidvincze]

Thank you for the fix.