scripts: generator script for key provisioning json files

This python script is used to generate json files that contain key data and
en metadata that is used by nrfutil provisioning keys into nrf54h and
nrf54l devices.

Signed-off-by: Even Falch-Larsen <[email protected]>

scripts/generate_psa_key_attributes.py

@@ -0,0 +1,279 @@
+#
+# Copyright (c) 2025Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-4-Clause
+#
+
+"""
+Module for generating PSA key attribute binary blobs
+"""
+
+import argparse
+import struct
+import binascii
+import math
+import json
+import sys
+from pathlib import Path
+from enum import IntEnum
+from pathlib import Path
+from cryptography.hazmat.primitives import serialization
+
+class PsaKeyType(IntEnum):
+    """The type of the key"""
+
+    AES = 0x2400
+    ECC_TWISTED_EDWARDS = 0x4142
+    RAW_DATA = 0x1001
+
+
+class PsaKeyBits(IntEnum):
+    """Number of bits in the key"""
+
+    AES = 256
+    EDDSA = 255
+
+
+class PsaUsage(IntEnum):
+    """Permitted usage on a key"""
+
+    VERIFY_MESSAGE_EXPORT = 0x0801
+    ENCRYPT_DECRYPT = 0x0300
+    USAGE_DERIVE = 0x4000
+
+class PsaCracenUsageSceme(IntEnum):
+    NONE = 0xff
+    PROTECTED = 0
+    SEED = 1
+    ENCRYPTED = 2
+    RAW = 3
+
+class PsaKeyLifetime(IntEnum):
+    """Lifetime and location for storing key"""
+
+    PERSISTENT_CRACEN = 0x804E0001
+    PERSISTENT_CRACEN_KMU = 0x804E4B01
+
+
+class PsaAlgorithm(IntEnum):
+    """Algorithm that can be associated with a key. Not used for AES"""
+
+    NONE = 0
+    CBC = 0x04404000
+    EDDSA_PURE = 0x06000800
+
+
+class PlatformKeyAttributes:
+    def __init__(self,
+                 key_type: PsaKeyType,
+                 identifier: int,
+                 location: PsaKeyLifetime,
+                 usage: PsaUsage,
+                 algorithm: PsaAlgorithm,
+                 size: int,
+                 cracen_usage: PsaCracenUsageSceme = PsaCracenUsageSceme.NONE):
+
+        self.key_type = key_type
+        self.lifetime = location
+        self.usage = usage
+        self.alg0 = algorithm
+        self.alg1 = PsaAlgorithm.NONE
+        self.bits = size
+        self.identifier = identifier
+
+        if location == PsaKeyLifetime.PERSISTENT_CRACEN_KMU:
+            if cracen_usage == PsaCracenUsageSceme.NONE:
+                print("--cracen_usage must be set if location target is PERSISTENT_CRACEN_KMU")
+                return
+            self.identifier = 0x7fff0000 | (cracen_usage << 12) | (identifier & 0xff)
+
+        if self.key_type == PsaKeyType.AES:
+            self.alg1 = PsaAlgorithm.NONE
+        elif self.key_type == PsaKeyType.ECC_TWISTED_EDWARDS:
+            self.alg1 = PsaAlgorithm.NONE
+        elif self.key_type == PsaKeyType.RAW_DATA:
+            self.alg1 = PsaAlgorithm.NONE
+        else:
+            raise RuntimeError("Invalid key type")
+
+    def pack(self):
+        """Builds a binary blob compatible with the psa_key_attributes_s C struct"""
+
+        return struct.pack(
+            "<hhIIIIII",
+            self.key_type,
+            self.bits,
+            self.lifetime,
+            # Policy
+            self.usage,
+            self.alg0,
+            self.alg1,
+            self.identifier,
+            0,  # Reserved, only used if key id encodes owner id
+        )
+
+def is_valid_hexa_code(string):
+    try:
+        int(string, 16)
+        return True
+    except ValueError:
+        return False
+
+def main() -> None:
+    parser = argparse.ArgumentParser(
+        description="Generate PSA key attributes and write to stdout or"
+                    "create or append the information including the key to a"
+                    "nrfutil compatible json file. Also supports reading key"
+                    "from a PEM file in some cases",
+        allow_abbrev=False,
+    )
+
+    parser.add_argument(
+        "--usage",
+        help="Key usage",
+        type=str,
+        required=True,
+        choices=[x.name for x in PsaUsage],
+    )
+
+    parser.add_argument(
+        "--id",
+        help="Key identifier",
+        type=lambda number_string: int(number_string, 0),
+        required=True,
+    )
+
+    parser.add_argument(
+        "--type",
+        help="Key type",
+        type=str,
+        required=True,
+        choices=[x.name for x in PsaKeyType],
+    )
+
+    parser.add_argument(
+        "--size",
+        help="Key size in bits",
+        type=lambda number_string: int(number_string, 0),
+        required=True,
+    )
+
+    parser.add_argument(
+        "--algorithm",
+        help="Key algorithm",
+        type=str,
+        required=False,
+        default="NONE",
+        choices=[x.name for x in PsaAlgorithm],
+    )
+
+    parser.add_argument(
+        "--location",
+        help="Storage location",
+        type=str,
+        required=True,
+        choices=[x.name for x in PsaKeyLifetime],
+    )
+
+    parser.add_argument(
+        "--key",
+        help="Key value",
+        type=str,
+        required=False,
+    )
+
+    parser.add_argument(
+        "--trng-key",
+        help="Generate key randomly",
+        action="store_true",
+        required=False,
+    )
+
+    parser.add_argument(
+        "--key-from-file",
+        help="Read key from PEM file",
+        type=str,
+        required=False,
+    )
+
+    parser.add_argument(
+        "--bin-output",
+        help="Output metadata as binary",
+        action="store_true",
+        required=False,
+    )
+
+    parser.add_argument(
+        "--file",
+        help="JSON file to create or modify",
+        type=str,
+        required=False,
+    )
+
+    parser.add_argument(
+        "--cracen_usage",
+        help="CRACEN KMU Slot usage scheme",
+        type=str,
+        required=False,
+        default="NONE",
+        choices=[x.name for x in PsaCracenUsageSceme],
+    )
+
+    args = parser.parse_args()
+
+    metadata = PlatformKeyAttributes(key_type=PsaKeyType[args.type],
+                              identifier=args.id,
+                              location=PsaKeyLifetime[args.location],
+                              usage=PsaUsage[args.usage],
+                              algorithm=PsaAlgorithm[args.algorithm],
+                              size=args.size,
+                              cracen_usage=PsaCracenUsageSceme[args.cracen_usage]).pack()
+
+    metadata_str = binascii.hexlify(metadata).decode('utf-8').upper()
+
+    if args.file and Path(args.file).is_file():
+        with open(args.file, encoding="utf-8") as file:
+            json_data= json.load(file)
+    else:
+        json_data= json.loads('{ "version": 0, "keyslots": [ ]}')
+
+    if args.trng_key and args.key:
+        print("Can't have both --trng-key and --key")
+        return
+
+    if args.trng_key:
+        value  = f'TRNG:{int(math.ceil(args.size / 8))}'
+    elif args.key:
+        key = args.key.strip("0x")
+        if not is_valid_hexa_code(key):
+            print("Invalid KEY value")
+            return
+        value = f'0x{key}'
+    elif args.key_from_file:
+        with open(args.key_from_file, 'rb') as key_file:
+            key_data = key_file.read()
+            key = serialization.load_pem_public_key(key_data)
+            key = key.public_bytes(
+                encoding=serialization.Encoding.Raw,
+                format=serialization.PublicFormat.Raw
+            )
+            value = f'0x{key.hex()}'
+            print(f'{value}')
+    else:
+        print("Expecting either --key or --trng-key")
+        return
+
+    json_data["keyslots"].append({"metadata": f'0x{metadata_str}', "value": f'{value}'})
+    output = json.dumps(json_data, indent=4)
+
+    if args.file:
+        with open(args.file, "w", encoding="utf-8") as file:
+            file.write(output)
+    elif args.bin_output:
+        sys.stdout.buffer.write(metadata)
+    else:
+        print(output)
+
+
+if __name__ == "__main__":
+    main()