crypto: remove AES-GCM

src/borg/crypto/low_level.pyx

@@ -67,7 +67,6 @@ cdef extern from "openssl/evp.h":
         pass
 
     const EVP_CIPHER *EVP_aes_256_ctr()
-    const EVP_CIPHER *EVP_aes_256_gcm()
     const EVP_CIPHER *EVP_aes_256_ocb()
     const EVP_CIPHER *EVP_chacha20_poly1305()
 
@@ -668,18 +667,6 @@ cdef class _CHACHA_BASE(_AEAD_BASE):
         super().__init__(*args, **kwargs)
 
 
-cdef class AES256_GCM(_AES_BASE):
-    @staticmethod
-    def requirements_check():
-        if OPENSSL_VERSION_NUMBER < 0x10001040:
-            raise ValueError('AES GCM requires OpenSSL >= 1.0.1d. Detected: OpenSSL %08x' % OPENSSL_VERSION_NUMBER)
-
-    def __init__(self, mac_key, enc_key, iv=None, header_len=1, aad_offset=1):
-        self.requirements_check()
-        self.cipher = EVP_aes_256_gcm
-        super().__init__(mac_key, enc_key, iv=iv, header_len=header_len, aad_offset=aad_offset)
-
-
 cdef class AES256_OCB(_AES_BASE):
     @staticmethod
     def requirements_check():

src/borg/testsuite/crypto.py

@@ -1,6 +1,6 @@
 from binascii import hexlify, unhexlify
 
-from ..crypto.low_level import AES256_CTR_HMAC_SHA256, AES256_GCM, AES256_OCB, CHACHA20_POLY1305, UNENCRYPTED, \
+from ..crypto.low_level import AES256_CTR_HMAC_SHA256, AES256_OCB, CHACHA20_POLY1305, UNENCRYPTED, \
                                IntegrityError, blake2b_256, hmac_sha256, openssl10
 from ..crypto.low_level import bytes_to_long, bytes_to_int, long_to_bytes
 from ..crypto.low_level import hkdf_hmac_sha512
@@ -97,10 +97,7 @@ class CryptoTestCase(BaseTestCase):
         data = b'foo' * 10
         header = b'\x23'
         tests = [
-            # ciphersuite class, exp_mac, exp_cdata
-            (AES256_GCM,
-             b'66a438843aa41a087d6a7ed1dc1f3c4c',
-             b'5bbb40be14e4bcbfc75715b77b1242d590d2bf9f7f8a8a910b4469888689', )
+            # (ciphersuite class, exp_mac, exp_cdata)
         ]
         if not openssl10:
             tests += [
@@ -144,10 +141,7 @@ class CryptoTestCase(BaseTestCase):
         data = b'foo' * 10
         header = b'\x12\x34\x56'
         tests = [
-            # ciphersuite class, exp_mac, exp_cdata
-            (AES256_GCM,
-             b'4fb0e5b0a0bca57527352cc6240e7cca',
-             b'5bbb40be14e4bcbfc75715b77b1242d590d2bf9f7f8a8a910b4469888689', )
+            # (ciphersuite class, exp_mac, exp_cdata)
         ]
         if not openssl10:
             tests += [