diff --git a/bip-0374/gen_test_vectors.py b/bip-0374/gen_test_vectors.py
index bbd87466..a828074e 100755
--- a/bip-0374/gen_test_vectors.py
+++ b/bip-0374/gen_test_vectors.py
@@ -2,13 +2,12 @@
 """Generate the BIP-0374 test vectors."""
 import csv
 from pathlib import Path
-import sys
 from reference import (
-    TaggedHash,
     dleq_generate_proof,
     dleq_verify_proof,
 )
 from secp256k1lab.secp256k1 import G as GENERATOR, GE
+from secp256k1lab.util import tagged_hash
 
 
 NUM_SUCCESS_TEST_VECTORS = 8
@@ -19,12 +18,12 @@ FILENAME_VERIFY_PROOF_TEST = Path(__file__).parent / 'test_vectors_verify_proof.
 
 
 def random_scalar_int(vector_i, purpose):
-    rng_out = TaggedHash(DLEQ_TAG_TESTVECTORS_RNG, purpose.encode() + vector_i.to_bytes(4, 'little'))
+    rng_out = tagged_hash(DLEQ_TAG_TESTVECTORS_RNG, purpose.encode() + vector_i.to_bytes(4, 'little'))
     return int.from_bytes(rng_out, 'big') % GE.ORDER
 
 
 def random_bytes(vector_i, purpose):
-    rng_out = TaggedHash(DLEQ_TAG_TESTVECTORS_RNG, purpose.encode() + vector_i.to_bytes(4, 'little'))
+    rng_out = tagged_hash(DLEQ_TAG_TESTVECTORS_RNG, purpose.encode() + vector_i.to_bytes(4, 'little'))
     return rng_out
 
 
diff --git a/bip-0374/reference.py b/bip-0374/reference.py
index ff9f22eb..8068b9c2 100755
--- a/bip-0374/reference.py
+++ b/bip-0374/reference.py
@@ -2,7 +2,6 @@
 
 """Reference implementation of DLEQ BIP for secp256k1 with unit tests."""
 
-from hashlib import sha256
 from pathlib import Path
 import random
 import sys
@@ -11,6 +10,7 @@ import unittest
 # Prefer the vendored copy of secp256k1lab
 sys.path.insert(0, str(Path(__file__).parent / "secp256k1lab/src"))
 from secp256k1lab.secp256k1 import G, GE
+from secp256k1lab.util import tagged_hash, xor_bytes
 
 
 DLEQ_TAG_AUX = "BIP0374/aux"
@@ -18,18 +18,6 @@ DLEQ_TAG_NONCE = "BIP0374/nonce"
 DLEQ_TAG_CHALLENGE = "BIP0374/challenge"
 
 
-def TaggedHash(tag: str, data: bytes) -> bytes:
-    ss = sha256(tag.encode()).digest()
-    ss += ss
-    ss += data
-    return sha256(ss).digest()
-
-
-def xor_bytes(lhs: bytes, rhs: bytes) -> bytes:
-    assert len(lhs) == len(rhs)
-    return bytes([lhs[i] ^ rhs[i] for i in range(len(lhs))])
-
-
 def dleq_challenge(
     A: GE, B: GE, C: GE, R1: GE, R2: GE, m: bytes | None, G: GE,
 ) -> int:
@@ -37,7 +25,7 @@ def dleq_challenge(
         assert len(m) == 32
     m = bytes([]) if m is None else m
     return int.from_bytes(
-        TaggedHash(
+        tagged_hash(
             DLEQ_TAG_CHALLENGE,
             A.to_bytes_compressed()
             + B.to_bytes_compressed()
@@ -63,9 +51,9 @@ def dleq_generate_proof(
         assert len(m) == 32
     A = a * G
     C = a * B
-    t = xor_bytes(a.to_bytes(32, "big"), TaggedHash(DLEQ_TAG_AUX, r))
+    t = xor_bytes(a.to_bytes(32, "big"), tagged_hash(DLEQ_TAG_AUX, r))
     m_prime = bytes([]) if m is None else m
-    rand = TaggedHash(
+    rand = tagged_hash(
         DLEQ_TAG_NONCE, t + A.to_bytes_compressed() + C.to_bytes_compressed() + m_prime
     )
     k = int.from_bytes(rand, "big") % GE.ORDER