Add test vectors code

1 files changed, 386 insertions, 1 deletions

diff --git a/tests/test_bip340.py b/tests/test_bip340.py
index cc9e416..8df8115 100644
--- a/tests/test_bip340.py
+++ b/tests/test_bip340.py
@@ -3,7 +3,23 @@ import csv
 from pathlib import Path
 from typing import Any
 
-from nostr.bip340 import pubkey_gen, schnorr_sign, schnorr_verify
+from nostr.bip340 import (
+    pubkey_gen,
+    schnorr_sign,
+    schnorr_verify,
+    bytes_from_int,
+    int_from_bytes,
+    point_mul,
+    lift_x,
+    G,
+    y,
+    is_infinite,
+    p,
+    n,
+    bytes_from_point,
+    has_even_y,
+    tagged_hash,
+)
 
 TEST_VECTORS = Path(__file__).parent / "test-vectors.csv"
 
@@ -40,3 +56,372 @@ def test_vectors():
 
             result_actual = schnorr_verify(msg, pubkey, sig)
             assert result == result_actual
+
+
+def is_square(x):
+    return int(pow(x, (p - 1) // 2, p)) == 1
+
+
+def has_square_y(P):
+    """Determine if P has a square Y coordinate. Used in an earlier draft of BIP340."""
+    assert not is_infinite(P)
+    return is_square(P[1])
+
+
+def test_vector0():
+    seckey = bytes_from_int(3)
+    msg = bytes_from_int(0)
+    aux_rand = bytes_from_int(0)
+    sig = schnorr_sign(msg, seckey, aux_rand)
+    pubkey = pubkey_gen(seckey)
+
+    # We should have at least one test vector where the seckey needs to be
+    # negated and one where it doesn't. In this one the seckey doesn't need to
+    # be negated.
+    x = int_from_bytes(seckey)
+    P = point_mul(G, x)
+    assert y(P) % 2 == 0
+
+    # For historical reasons (pubkey tiebreaker was squareness and not evenness)
+    # we should have at least one test vector where the the point reconstructed
+    # from the public key has a square and one where it has a non-square Y
+    # coordinate. In this one Y is non-square.
+    pubkey_point = lift_x(pubkey)
+    assert not has_square_y(pubkey_point)
+
+    # For historical reasons (R tiebreaker was squareness and not evenness)
+    # we should have at least one test vector where the the point reconstructed
+    # from the R.x coordinate has a square and one where it has a non-square Y
+    # coordinate. In this one Y is non-square.
+    R = lift_x(sig[0:32])
+    assert not has_square_y(R)
+
+    return (seckey, pubkey, aux_rand, msg, sig, "TRUE", None)
+
+
+def test_vector1():
+    seckey = bytes_from_int(
+        0xB7E151628AED2A6ABF7158809CF4F3C762E7160F38B4DA56A784D9045190CFEF
+    )
+    msg = bytes_from_int(
+        0x243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89
+    )
+    aux_rand = bytes_from_int(1)
+
+    sig = schnorr_sign(msg, seckey, aux_rand)
+
+    # The point reconstructed from the R.x coordinate has a square Y coordinate.
+    R = lift_x(sig[0:32])
+    assert has_square_y(R)
+
+    return (seckey, pubkey_gen(seckey), aux_rand, msg, sig, "TRUE", None)
+
+
+def test_vector2():
+    seckey = bytes_from_int(
+        0xC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B14E5C9
+    )
+    msg = bytes_from_int(
+        0x7E2D58D8B3BCDF1ABADEC7829054F90DDA9805AAB56C77333024B9D0A508B75C
+    )
+    aux_rand = bytes_from_int(
+        0xC87AA53824B4D7AE2EB035A2B5BBBCCC080E76CDC6D1692C4B0B62D798E6D906
+    )
+    sig = schnorr_sign(msg, seckey, aux_rand)
+
+    # The point reconstructed from the public key has a square Y coordinate.
+    pubkey = pubkey_gen(seckey)
+    pubkey_point = lift_x(pubkey)
+    assert has_square_y(pubkey_point)
+
+    # This signature vector would not verify if the implementer checked the
+    # evenness of the X coordinate of R instead of the Y coordinate.
+    R = lift_x(sig[0:32])
+    assert R[0] % 2 == 1
+
+    return (seckey, pubkey, aux_rand, msg, sig, "TRUE", None)
+
+
+def test_vector3():
+    seckey = bytes_from_int(
+        0x0B432B2677937381AEF05BB02A66ECD012773062CF3FA2549E44F58ED2401710
+    )
+
+    # Need to negate this seckey before signing
+    x = int_from_bytes(seckey)
+    P = point_mul(G, x)
+    assert y(P) % 2 != 0
+
+    msg = bytes_from_int(
+        0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
+    )
+    aux_rand = bytes_from_int(
+        0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
+    )
+
+    sig = schnorr_sign(msg, seckey, aux_rand)
+    return (
+        seckey,
+        pubkey_gen(seckey),
+        aux_rand,
+        msg,
+        sig,
+        "TRUE",
+        "test fails if msg is reduced modulo p or n",
+    )
+
+
+# Signs with a given nonce. This can be INSECURE and is only INTENDED FOR
+# GENERATING TEST VECTORS. Results in an invalid signature if y(kG) is not
+# even.
+def insecure_schnorr_sign_fixed_nonce(msg, seckey0, k):
+    if len(msg) != 32:
+        raise ValueError("The message must be a 32-byte array.")
+    seckey0 = int_from_bytes(seckey0)
+    if not (1 <= seckey0 <= n - 1):
+        raise ValueError("The secret key must be an integer in the range 1..n-1.")
+    P = point_mul(G, seckey0)
+    seckey = seckey0 if has_even_y(P) else n - seckey0
+    R = point_mul(G, k)
+    e = (
+        int_from_bytes(
+            tagged_hash(
+                "BIP0340/challenge", bytes_from_point(R) + bytes_from_point(P) + msg
+            )
+        )
+        % n
+    )
+    return bytes_from_point(R) + bytes_from_int((k + e * seckey) % n)
+
+
+# Creates a singature with a small x(R) by using k = -1/2
+def test_vector4():
+    one_half = n - 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0
+    seckey = bytes_from_int(
+        0x763758E5CBEEDEE4F7D3FC86F531C36578933228998226672F13C4F0EBE855EB
+    )
+    msg = bytes_from_int(
+        0x4DF3C3F68FCC83B27E9D42C90431A72499F17875C81A599B566C9889B9696703
+    )
+    sig = insecure_schnorr_sign_fixed_nonce(msg, seckey, one_half)
+    return (None, pubkey_gen(seckey), None, msg, sig, "TRUE", None)
+
+
+default_seckey = bytes_from_int(
+    0xB7E151628AED2A6ABF7158809CF4F3C762E7160F38B4DA56A784D9045190CFEF
+)
+default_msg = bytes_from_int(
+    0x243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89
+)
+default_aux_rand = bytes_from_int(
+    0xC87AA53824B4D7AE2EB035A2B5BBBCCC080E76CDC6D1692C4B0B62D798E6D906
+)
+
+# Public key is not on the curve
+def test_vector5():
+    # This creates a dummy signature that doesn't have anything to do with the
+    # public key.
+    seckey = default_seckey
+    msg = default_msg
+    sig = schnorr_sign(msg, seckey, default_aux_rand)
+
+    pubkey = bytes_from_int(
+        0xEEFDEA4CDB677750A420FEE807EACF21EB9898AE79B9768766E4FAA04A2D4A34
+    )
+    assert lift_x(pubkey) is None
+
+    return (None, pubkey, None, msg, sig, "FALSE", "public key not on the curve")
+
+
+def test_vector6():
+    seckey = default_seckey
+    msg = default_msg
+    k = 6
+    sig = insecure_schnorr_sign_fixed_nonce(msg, seckey, k)
+
+    # Y coordinate of R is not even
+    R = point_mul(G, k)
+    assert not has_even_y(R)
+
+    return (None, pubkey_gen(seckey), None, msg, sig, "FALSE", "has_even_y(R) is false")
+
+
+def test_vector7():
+    seckey = default_seckey
+    msg = int_from_bytes(default_msg)
+    neg_msg = bytes_from_int(n - msg)
+    sig = schnorr_sign(neg_msg, seckey, default_aux_rand)
+    return (
+        None,
+        pubkey_gen(seckey),
+        None,
+        bytes_from_int(msg),
+        sig,
+        "FALSE",
+        "negated message",
+    )
+
+
+def test_vector8():
+    seckey = default_seckey
+    msg = default_msg
+    sig = schnorr_sign(msg, seckey, default_aux_rand)
+    sig = sig[0:32] + bytes_from_int(n - int_from_bytes(sig[32:64]))
+    return (None, pubkey_gen(seckey), None, msg, sig, "FALSE", "negated s value")
+
+
+def bytes_from_point_inf0(P):
+    if P == None:
+        return bytes_from_int(0)
+    return bytes_from_int(P[0])
+
+
+def test_vector9():
+    seckey = default_seckey
+    msg = default_msg
+
+    # Override bytes_from_point in schnorr_sign to allow creating a signature
+    # with k = 0.
+    k = 0
+    bytes_from_point_tmp = bytes_from_point.__code__
+    bytes_from_point.__code__ = bytes_from_point_inf0.__code__
+    sig = insecure_schnorr_sign_fixed_nonce(msg, seckey, k)
+    bytes_from_point.__code__ = bytes_from_point_tmp
+
+    return (
+        None,
+        pubkey_gen(seckey),
+        None,
+        msg,
+        sig,
+        "FALSE",
+        "sG - eP is infinite. Test fails in single verification if has_even_y(inf) is defined as true and x(inf) as 0",
+    )
+
+
+def bytes_from_point_inf1(P):
+    if P == None:
+        return bytes_from_int(1)
+    return bytes_from_int(P[0])
+
+
+def test_vector10():
+    seckey = default_seckey
+    msg = default_msg
+
+    # Override bytes_from_point in schnorr_sign to allow creating a signature
+    # with k = 0.
+    k = 0
+    bytes_from_point_tmp = bytes_from_point.__code__
+    bytes_from_point.__code__ = bytes_from_point_inf1.__code__
+    sig = insecure_schnorr_sign_fixed_nonce(msg, seckey, k)
+    bytes_from_point.__code__ = bytes_from_point_tmp
+
+    return (
+        None,
+        pubkey_gen(seckey),
+        None,
+        msg,
+        sig,
+        "FALSE",
+        "sG - eP is infinite. Test fails in single verification if has_even_y(inf) is defined as true and x(inf) as 1",
+    )
+
+
+# It's cryptographically impossible to create a test vector that fails if run
+# in an implementation which merely misses the check that sig[0:32] is an X
+# coordinate on the curve. This test vector just increases test coverage.
+def test_vector11():
+    seckey = default_seckey
+    msg = default_msg
+    sig = schnorr_sign(msg, seckey, default_aux_rand)
+
+    # Replace R's X coordinate with an X coordinate that's not on the curve
+    x_not_on_curve = bytes_from_int(
+        0x4A298DACAE57395A15D0795DDBFD1DCB564DA82B0F269BC70A74F8220429BA1D
+    )
+    assert lift_x(x_not_on_curve) is None
+    sig = x_not_on_curve + sig[32:64]
+
+    return (
+        None,
+        pubkey_gen(seckey),
+        None,
+        msg,
+        sig,
+        "FALSE",
+        "sig[0:32] is not an X coordinate on the curve",
+    )
+
+
+# It's cryptographically impossible to create a test vector that fails if run
+# in an implementation which merely misses the check that sig[0:32] is smaller
+# than the field size. This test vector just increases test coverage.
+def test_vector12():
+    seckey = default_seckey
+    msg = default_msg
+    sig = schnorr_sign(msg, seckey, default_aux_rand)
+
+    # Replace R's X coordinate with an X coordinate that's equal to field size
+    sig = bytes_from_int(p) + sig[32:64]
+
+    return (
+        None,
+        pubkey_gen(seckey),
+        None,
+        msg,
+        sig,
+        "FALSE",
+        "sig[0:32] is equal to field size",
+    )
+
+
+# It's cryptographically impossible to create a test vector that fails if run
+# in an implementation which merely misses the check that sig[32:64] is smaller
+# than the curve order. This test vector just increases test coverage.
+def test_vector13():
+    seckey = default_seckey
+    msg = default_msg
+    sig = schnorr_sign(msg, seckey, default_aux_rand)
+
+    # Replace s with a number that's equal to the curve order
+    sig = sig[0:32] + bytes_from_int(n)
+
+    return (
+        None,
+        pubkey_gen(seckey),
+        None,
+        msg,
+        sig,
+        "FALSE",
+        "sig[32:64] is equal to curve order",
+    )
+
+
+# Test out of range pubkey
+# It's cryptographically impossible to create a test vector that fails if run
+# in an implementation which accepts out of range pubkeys because we can't find
+# a secret key for such a public key and therefore can not create a signature.
+# This test vector just increases test coverage.
+def test_vector14():
+    # This creates a dummy signature that doesn't have anything to do with the
+    # public key.
+    seckey = default_seckey
+    msg = default_msg
+    sig = schnorr_sign(msg, seckey, default_aux_rand)
+    pubkey_int = p + 1
+    pubkey = bytes_from_int(pubkey_int)
+    assert lift_x(pubkey) is None
+    # If an implementation would reduce a given public key modulo p then the
+    # pubkey would be valid
+    assert lift_x(bytes_from_int(pubkey_int % p)) is not None
+
+    return (
+        None,
+        pubkey,
+        None,
+        msg,
+        sig,
+        "FALSE",
+        "public key is not a valid X coordinate because it exceeds the field size",
+    )