From a4602c6f61f8aec0e0c644c99dbe421ebba96a7b Mon Sep 17 00:00:00 2001
From: Thomas Waldmann <tw@waldmann-edv.de>
Date: Thu, 30 Nov 2023 19:53:09 +0100
Subject: [PATCH] remove unused hkdf_hmac_sha512 and related tests

---
 src/borg/crypto/low_level.pyx | 27 --------------
 src/borg/selftest.py          |  2 +-
 src/borg/testsuite/crypto.py  | 69 -----------------------------------
 3 files changed, 1 insertion(+), 97 deletions(-)

diff --git a/src/borg/crypto/low_level.pyx b/src/borg/crypto/low_level.pyx
index aa28aa14..2a42ef51 100644
--- a/src/borg/crypto/low_level.pyx
+++ b/src/borg/crypto/low_level.pyx
@@ -714,30 +714,3 @@ def blake2b_256(key, data):
 
 def blake2b_128(data):
     return hashlib.blake2b(data, digest_size=16).digest()
-
-
-def hkdf_hmac_sha512(ikm, salt, info, output_length):
-    """
-    Compute HKDF-HMAC-SHA512 with input key material *ikm*, *salt* and *info* to produce *output_length* bytes.
-
-    This is the "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)" (RFC 5869)
-    instantiated with HMAC-SHA512.
-
-    *output_length* must not be greater than 64 * 255 bytes.
-    """
-    digest_length = 64
-    assert output_length <= (255 * digest_length), 'output_length must be <= 255 * 64 bytes'
-    # Step 1. HKDF-Extract (ikm, salt) -> prk
-    if salt is None:
-        salt = bytes(64)
-    prk = hmac.digest(salt, ikm, 'sha512')
-
-    # Step 2. HKDF-Expand (prk, info, output_length) -> output key
-    n = ceil(output_length / digest_length)
-    t_n = b''
-    output = b''
-    for i in range(n):
-        msg = t_n + info + (i + 1).to_bytes(1, 'little')
-        t_n = hmac.digest(prk, msg, 'sha512')
-        output += t_n
-    return output[:output_length]
diff --git a/src/borg/selftest.py b/src/borg/selftest.py
index 49a9704c..8f6b693b 100644
--- a/src/borg/selftest.py
+++ b/src/borg/selftest.py
@@ -33,7 +33,7 @@ SELFTEST_CASES = [
     ChunkerTestCase,
 ]
 
-SELFTEST_COUNT = 38
+SELFTEST_COUNT = 33
 
 
 class SelfTestResult(TestResult):
diff --git a/src/borg/testsuite/crypto.py b/src/borg/testsuite/crypto.py
index 4e031899..d169dfce 100644
--- a/src/borg/testsuite/crypto.py
+++ b/src/borg/testsuite/crypto.py
@@ -7,7 +7,6 @@ import unittest
 
 from ..crypto.low_level import AES256_CTR_HMAC_SHA256, AES256_OCB, CHACHA20_POLY1305, UNENCRYPTED, IntegrityError
 from ..crypto.low_level import bytes_to_long, bytes_to_int, long_to_bytes
-from ..crypto.low_level import hkdf_hmac_sha512
 from ..crypto.low_level import AES, hmac_sha256
 from ..crypto.key import CHPOKeyfileKey, AESOCBRepoKey, FlexiKey
 from ..helpers import msgpack
@@ -195,74 +194,6 @@ class CryptoTestCase(BaseTestCase):
             cs = cs_cls(key, iv_int, header_len=len(header), aad_offset=0)
             self.assert_raises(IntegrityError, lambda: cs.decrypt(hdr_mac_iv_cdata, aad=b"incorrect_chunkid"))
 
-    # These test vectors come from https://www.kullo.net/blog/hkdf-sha-512-test-vectors/
-    # who claims to have verified these against independent Python and C++ implementations.
-
-    def test_hkdf_hmac_sha512(self):
-        ikm = b"\x0b" * 22
-        salt = bytes.fromhex("000102030405060708090a0b0c")
-        info = bytes.fromhex("f0f1f2f3f4f5f6f7f8f9")
-        length = 42
-
-        okm = hkdf_hmac_sha512(ikm, salt, info, length)
-        assert okm == bytes.fromhex(
-            "832390086cda71fb47625bb5ceb168e4c8e26a1a16ed34d9fc7fe92c1481579338da362cb8d9f925d7cb"
-        )
-
-    def test_hkdf_hmac_sha512_2(self):
-        ikm = bytes.fromhex(
-            "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f2021222324252627"
-            "28292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f"
-        )
-        salt = bytes.fromhex(
-            "606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868"
-            "788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeaf"
-        )
-        info = bytes.fromhex(
-            "b0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7"
-            "d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff"
-        )
-        length = 82
-
-        okm = hkdf_hmac_sha512(ikm, salt, info, length)
-        assert okm == bytes.fromhex(
-            "ce6c97192805b346e6161e821ed165673b84f400a2b514b2fe23d84cd189ddf1b695b48cbd1c838844"
-            "1137b3ce28f16aa64ba33ba466b24df6cfcb021ecff235f6a2056ce3af1de44d572097a8505d9e7a93"
-        )
-
-    def test_hkdf_hmac_sha512_3(self):
-        ikm = bytes.fromhex("0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b")
-        salt = None
-        info = b""
-        length = 42
-
-        okm = hkdf_hmac_sha512(ikm, salt, info, length)
-        assert okm == bytes.fromhex(
-            "f5fa02b18298a72a8c23898a8703472c6eb179dc204c03425c970e3b164bf90fff22d04836d0e2343bac"
-        )
-
-    def test_hkdf_hmac_sha512_4(self):
-        ikm = bytes.fromhex("0b0b0b0b0b0b0b0b0b0b0b")
-        salt = bytes.fromhex("000102030405060708090a0b0c")
-        info = bytes.fromhex("f0f1f2f3f4f5f6f7f8f9")
-        length = 42
-
-        okm = hkdf_hmac_sha512(ikm, salt, info, length)
-        assert okm == bytes.fromhex(
-            "7413e8997e020610fbf6823f2ce14bff01875db1ca55f68cfcf3954dc8aff53559bd5e3028b080f7c068"
-        )
-
-    def test_hkdf_hmac_sha512_5(self):
-        ikm = bytes.fromhex("0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c")
-        salt = None
-        info = b""
-        length = 42
-
-        okm = hkdf_hmac_sha512(ikm, salt, info, length)
-        assert okm == bytes.fromhex(
-            "1407d46013d98bc6decefcfee55f0f90b0c7f63d68eb1a80eaf07e953cfc0a3a5240a155d6e4daa965bb"
-        )
-
 
 def test_decrypt_key_file_argon2_chacha20_poly1305():
     plain = b"hello"