Add orchard_key_components.py.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

orchard_key_components.py

@@ -0,0 +1,144 @@
+#!/usr/bin/env python3
+import sys; assert sys.version_info[0] >= 3, "Python 3 required."
+
+from pyblake2 import blake2b, blake2s
+
+from orchard_generators import SPENDING_KEY_BASE, group_hash
+from orchard_pallas import Fp, Scalar, Point
+from orchard_merkle_tree import MERKLE_DEPTH
+from orchard_commitments import commit_ivk, note_commit
+from utils import leos2bsp, leos2ip, i2leosp
+from tv_output import render_args, render_tv
+
+#
+# Utilities
+#
+
+def to_scalar(buf):
+    return Scalar(leos2ip(buf))
+
+def to_base(buf):
+    return Fp(leos2ip(buf))
+
+
+#
+# PRFs and hashes
+#
+
+def prf_expand(sk, t):
+    digest = blake2b(person=b'Zcash_ExpandSeed')
+    digest.update(sk)
+    digest.update(t)
+    return digest.digest()
+
+def diversify_hash(d):
+    P = group_hash(b'z.cash:Orchard-gd', d)
+    if P == Point.identity():
+        P = group_hash(b'z.cash:Orchard-gd', b'')
+    return P
+
+#
+# Key components
+#
+
+class SpendingKey:
+    def __init__(self, data):
+        self.data = data
+
+        self.ask  = to_scalar(prf_expand(self.data, b'\x06'))
+        self.nk   = to_base(prf_expand(self.data, b'\x07'))
+        self.rivk = to_scalar(prf_expand(self.data, b'\x08'))
+        if self.ask == Scalar.ZERO:
+            raise ValueError("invalid spending key")
+
+        self.akP = SPENDING_KEY_BASE * self.ask
+        if bytes(self.akP)[-1] & 0x80 != 0:
+            self.ask = -self.ask
+
+        self.ak = self.akP.extract()
+        if commit_ivk(self.rivk, self.ak, self.nk) is None:
+            raise ValueError("invalid spending key")
+
+
+class FullViewingKey(object):
+    def __init__(self, sk):
+        (self.rivk, self.ak, self.nk) = (sk.rivk, sk.ak, sk.nk)
+        K = i2leosp(256, self.rivk.s)
+        R = prf_expand(K, b'\x82' + i2leosp(256, self.ak.s) + i2leosp(256, self.nk.s))
+        self.dk = R[:32]
+        self.ovk = R[32:]
+
+    def ivk(self):
+        return commit_ivk(self.rivk, self.ak, self.nk)
+
+    def ovk(self):
+        return prf_expand(self.data, b'\x02')[:32]
+
+    def default_d(self):
+        return i2leosp(88, 1337)
+
+    def default_pkd(self):
+        return diversify_hash(self.default_d()) * self.ivk()
+
+
+def main():
+    args = render_args()
+
+    test_vectors = []
+    for i in range(0, 10):
+        sys.stdout.write(".")
+        sys.stdout.flush()
+        sk = SpendingKey(bytes([i] * 32))
+        fvk = FullViewingKey(sk)
+        note_v = (2548793025584392057432895043257984320*i) % 2**64
+        note_r = Scalar(8890123457840276890326754358439057438290574382905).exp(i+1)
+        note_rho = Fp(342358729643275392567239275209835729829*i)
+        note_psi = Fp(432592604358294371936572103719358723958*i)
+        note_cm = note_commit(
+            note_r,
+            leos2bsp(bytes(diversify_hash(fvk.default_d()))),
+            leos2bsp(bytes(fvk.default_pkd())),
+            note_v,
+            note_rho,
+            note_psi)
+        note_nf = b"0"*32 #note_nullifier(fvk.nk(), note_cm)
+        test_vectors.append({
+            'sk': sk.data,
+            'ask': bytes(sk.ask),
+            'ovk': fvk.ovk,
+            'rivk': bytes(fvk.rivk),
+            'ak': bytes(fvk.ak),
+            'nk': bytes(fvk.nk),
+            'ivk': bytes(fvk.ivk()),
+            'default_d': fvk.default_d(),
+            'default_pk_d': bytes(fvk.default_pkd()),
+            'note_v': note_v,
+            'note_r': bytes(note_r),
+            'note_cmx': bytes(note_cm.extract()),
+            'note_nf': note_nf,
+        })
+
+    render_tv(
+        args,
+        'orchard_key_components',
+        (
+            ('sk', '[u8; 32]'),
+            ('ask', '[u8; 32]'),
+            ('ovk', '[u8; 32]'),
+            ('rivk', '[u8; 32]'),
+            ('ak', '[u8; 32]'),
+            ('nk', '[u8; 32]'),
+            ('ivk', '[u8; 32]'),
+            ('default_d', '[u8; 11]'),
+            ('default_pk_d', '[u8; 32]'),
+            ('note_v', 'u64'),
+            ('note_r', '[u8; 32]'),
+            ('note_cmx', '[u8; 32]'),
+            ('note_nf', '[u8; 32]'),
+        ),
+        test_vectors,
+    )
+
+
+if __name__ == '__main__':
+    main()