diff --git a/electrum/crypto.py b/electrum/crypto.py
index 69dbe2cdd..f767e25f1 100644
--- a/electrum/crypto.py
+++ b/electrum/crypto.py
@@ -338,7 +338,7 @@ def chacha20_poly1305_encrypt(
     assert isinstance(nonce, (bytes, bytearray))
     assert isinstance(associated_data, (bytes, bytearray, type(None)))
     assert isinstance(data, (bytes, bytearray))
-    assert len(key) == 32, f"unexpected key size: {len(nonce)} (expected: 32)"
+    assert len(key) == 32, f"unexpected key size: {len(key)} (expected: 32)"
     assert len(nonce) == 12, f"unexpected nonce size: {len(nonce)} (expected: 12)"
     if HAS_CRYPTODOME:
         cipher = CD_ChaCha20_Poly1305.new(key=key, nonce=nonce)
@@ -363,7 +363,7 @@ def chacha20_poly1305_decrypt(
     assert isinstance(nonce, (bytes, bytearray))
     assert isinstance(associated_data, (bytes, bytearray, type(None)))
     assert isinstance(data, (bytes, bytearray))
-    assert len(key) == 32, f"unexpected key size: {len(nonce)} (expected: 32)"
+    assert len(key) == 32, f"unexpected key size: {len(key)} (expected: 32)"
     assert len(nonce) == 12, f"unexpected nonce size: {len(nonce)} (expected: 12)"
     if HAS_CRYPTODOME:
         cipher = CD_ChaCha20_Poly1305.new(key=key, nonce=nonce)
@@ -384,7 +384,7 @@ def chacha20_encrypt(*, key: bytes, nonce: bytes, data: bytes) -> bytes:
     assert isinstance(key, (bytes, bytearray))
     assert isinstance(nonce, (bytes, bytearray))
     assert isinstance(data, (bytes, bytearray))
-    assert len(key) == 32, f"unexpected key size: {len(nonce)} (expected: 32)"
+    assert len(key) == 32, f"unexpected key size: {len(key)} (expected: 32)"
     assert len(nonce) in (8, 12), f"unexpected nonce size: {len(nonce)} (expected: 8 or 12)"
     if HAS_CRYPTODOME:
         cipher = CD_ChaCha20.new(key=key, nonce=nonce)
@@ -402,7 +402,7 @@ def chacha20_decrypt(*, key: bytes, nonce: bytes, data: bytes) -> bytes:
     assert isinstance(key, (bytes, bytearray))
     assert isinstance(nonce, (bytes, bytearray))
     assert isinstance(data, (bytes, bytearray))
-    assert len(key) == 32, f"unexpected key size: {len(nonce)} (expected: 32)"
+    assert len(key) == 32, f"unexpected key size: {len(key)} (expected: 32)"
     assert len(nonce) in (8, 12), f"unexpected nonce size: {len(nonce)} (expected: 8 or 12)"
     if HAS_CRYPTODOME:
         cipher = CD_ChaCha20.new(key=key, nonce=nonce)