Merge pull request #16 from tomato42/pkcs-files

Import/Export to IETF file formats

Author: GiacomoPope

.github/workflows/ci.yml

@@ -43,6 +43,22 @@ jobs:
           - name: py3.12
             os: ubuntu-latest
             python-version: "3.12"
+          - name: py3.9 with ecdsa
+            os: ubuntu-latest
+            python-version: "3.9"
+            opt-deps: ['ecdsa']
+          - name: py3.10 with ecdsa
+            os: ubuntu-latest
+            python-version: "3.10"
+            opt-deps: ['ecdsa']
+          - name: py3.11 with ecdsa
+            os: ubuntu-latest
+            python-version: "3.11"
+            opt-deps: ['ecdsa']
+          - name: py3.12 with ecdsa
+            os: ubuntu-latest
+            python-version: "3.12"
+            opt-deps: ['ecdsa']
     steps:
       - uses: actions/checkout@v4
         with:
@@ -66,6 +82,10 @@ jobs:
       - name: Install build dependencies
         run: |
           pip install -r requirements.txt
+      - name: Install ecdsa
+        if: ${{ contains(matrix.opt-deps, 'ecdsa') }}
+        run: |
+          pip install ecdsa
       - name: Display installed python package versions
         run: |
           pip list || :

pyproject.toml

@@ -14,6 +14,11 @@ classifiers = [
 ]
 license = "MIT"
 
+[project.optional-dependencies]
+pkcs = [
+    "ecdsa>=0.19.1",
+]
+
 [project.urls]
 Homepage = "https://github.com/GiacomoPope/dilithium-py"
 Issues = "https://github.com/GiacomoPope/dilithium-py/issues"

src/dilithium_py/ml_dsa/default_parameters.py

@@ -11,6 +11,7 @@
         "eta": 2,  # Private key range
         "omega": 80,  # Max number of ones in hint
         "c_tilde_bytes": 32,
+        "oid": (2, 16, 840, 1, 101, 3, 4, 3, 17),
     },
     "ML_DSA_65": {
         "d": 13,  # number of bits dropped from t
@@ -22,6 +23,7 @@
         "eta": 4,  # Private key range
         "omega": 55,  # Max number of ones in hint
         "c_tilde_bytes": 48,
+        "oid": (2, 16, 840, 1, 101, 3, 4, 3, 18),
     },
     "ML_DSA_87": {
         "d": 13,  # number of bits dropped from t
@@ -33,6 +35,7 @@
         "eta": 2,  # Private key range
         "omega": 75,  # Max number of ones in hint
         "c_tilde_bytes": 64,
+        "oid": (2, 16, 840, 1, 101, 3, 4, 3, 19),
     },
 }
 

src/dilithium_py/ml_dsa/ml_dsa.py

@@ -22,6 +22,7 @@ def __init__(self, parameter_set):
 
         self.M = ModuleDilithium()
         self.R = self.M.ring
+        self.oid = parameter_set["oid"] if "oid" in parameter_set else None
 
         # Use system randomness by default, for deterministic randomness
         # use the method `set_drbg_seed()`
@@ -123,11 +124,26 @@ def _pack_h(self, h):
     def _pack_sig(self, c_tilde, z, h):
         return c_tilde + z.bit_pack_z(self.gamma_1) + self._pack_h(h)
 
+    def _pk_size(self):
+        return 32 + 32 * self.k * 10
+
     def _unpack_pk(self, pk_bytes):
+        if len(pk_bytes) != self._pk_size():
+            raise ValueError("PK packed bytes is of the wrong length")
         rho, t1_bytes = pk_bytes[:32], pk_bytes[32:]
         t1 = self.M.bit_unpack_t1(t1_bytes, self.k, 1)
         return rho, t1
 
+    def _sk_size(self):
+        if self.eta == 2:
+            s_bytes = 96
+        else:
+            s_bytes = 128
+        s1_len = s_bytes * self.l
+        s2_len = s_bytes * self.k
+        t0_len = 416 * self.k
+        return 2 * 32 + 64 + s1_len + s2_len + t0_len
+
     def _unpack_sk(self, sk_bytes):
         if self.eta == 2:
             s_bytes = 96
@@ -136,7 +152,7 @@ def _unpack_sk(self, sk_bytes):
         s1_len = s_bytes * self.l
         s2_len = s_bytes * self.k
         t0_len = 416 * self.k
-        if len(sk_bytes) != 2 * 32 + 64 + s1_len + s2_len + t0_len:
+        if len(sk_bytes) != self._sk_size():
             raise ValueError("SK packed bytes is of the wrong length")
 
         # Split bytes between seeds and vectors
@@ -404,6 +420,11 @@ def prehash_external_mu(self, pk_bytes, m, ctx=b""):
             raise ValueError(
                 f"ctx bytes must have length at most 255, ctx has length {len(ctx) = }"
             )
+        if len(pk_bytes) != self._pk_size():
+            raise ValueError(
+                f"Public key size doesn't match this ML-DSA object parameters,"
+                f"received {len(pk_bytes) = }, expected: {self._pk_size()}"
+            )
 
         # Format the message using the context
         m_prime = bytes([0]) + bytes([len(ctx)]) + ctx + m