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crypto: cleanup, remove references to AES-GCM 

A lot of people have concerns about AES-GCM.

Considering we can use AES-OCB, I guess we will
not use AES-GCM anyway, thus no need to talk
about it.
This commit is contained in:
Thomas Waldmann 2022-03-17 20:50:37 +01:00
parent d3f069cb3b
commit aff626119a
1 changed files with 10 additions and 10 deletions
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20
src/borg/crypto/low_level.pyx
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@ -77,9 +77,9 @@ cdef extern from "openssl/evp.h":
int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr)
int EVP_CTRL_GCM_GET_TAG
int EVP_CTRL_GCM_SET_TAG
int EVP_CTRL_GCM_SET_IVLEN
int EVP_CTRL_AEAD_GET_TAG
int EVP_CTRL_AEAD_SET_TAG
int EVP_CTRL_AEAD_SET_IVLEN
const EVP_MD *EVP_sha256() nogil
@ -471,7 +471,7 @@ cdef class _AEAD_BASE:
if iv is not None:
self.set_iv(iv)
assert self.blocks == 0, 'iv needs to be set before encrypt is called'
# AES-GCM, AES-OCB, CHACHA20 ciphers all add a internal 32bit counter to the 96bit (12Byte)
# AES-OCB, CHACHA20 ciphers all add a internal 32bit counter to the 96bit (12Byte)
# IV we provide, thus we must not encrypt more than 2^32 cipher blocks with same IV).
block_count = self.block_count(len(data))
if block_count > 2**32:
@ -499,7 +499,7 @@ cdef class _AEAD_BASE:
rc = EVP_EncryptInit_ex(self.ctx, self.cipher(), NULL, NULL, NULL)
if not rc:
raise CryptoError('EVP_EncryptInit_ex failed')
if not EVP_CIPHER_CTX_ctrl(self.ctx, EVP_CTRL_GCM_SET_IVLEN, self.iv_len, NULL):
if not EVP_CIPHER_CTX_ctrl(self.ctx, EVP_CTRL_AEAD_SET_IVLEN, self.iv_len, NULL):
raise CryptoError('EVP_CIPHER_CTX_ctrl SET IVLEN failed')
rc = EVP_EncryptInit_ex(self.ctx, NULL, NULL, self.enc_key, self.iv)
if not rc:
@ -518,7 +518,7 @@ cdef class _AEAD_BASE:
if not rc:
raise CryptoError('EVP_EncryptFinal_ex failed')
offset += olen
if not EVP_CIPHER_CTX_ctrl(self.ctx, EVP_CTRL_GCM_GET_TAG, self.mac_len, odata+hlen):
if not EVP_CIPHER_CTX_ctrl(self.ctx, EVP_CTRL_AEAD_GET_TAG, self.mac_len, odata + hlen):
raise CryptoError('EVP_CIPHER_CTX_ctrl GET TAG failed')
self.blocks = block_count
return odata[:offset]
@ -531,7 +531,7 @@ cdef class _AEAD_BASE:
"""
authenticate aad + iv + cdata, decrypt cdata, ignore header bytes up to aad_offset.
"""
# AES-GCM, AES-OCB, CHACHA20 ciphers all add a internal 32bit counter to the 96bit (12Byte)
# AES-OCB, CHACHA20 ciphers all add a internal 32bit counter to the 96bit (12Byte)
# IV we provide, thus we must not decrypt more than 2^32 cipher blocks with same IV):
approx_block_count = self.block_count(len(envelope)) # sloppy, but good enough for borg
if approx_block_count > 2**32:
@ -552,11 +552,11 @@ cdef class _AEAD_BASE:
raise CryptoError('EVP_DecryptInit_ex failed')
iv = self.fetch_iv(<unsigned char *> idata.buf+hlen+self.mac_len)
self.set_iv(iv)
if not EVP_CIPHER_CTX_ctrl(self.ctx, EVP_CTRL_GCM_SET_IVLEN, self.iv_len, NULL):
if not EVP_CIPHER_CTX_ctrl(self.ctx, EVP_CTRL_AEAD_SET_IVLEN, self.iv_len, NULL):
raise CryptoError('EVP_CIPHER_CTX_ctrl SET IVLEN failed')
if not EVP_DecryptInit_ex(self.ctx, NULL, NULL, self.enc_key, iv):
raise CryptoError('EVP_DecryptInit_ex failed')
if not EVP_CIPHER_CTX_ctrl(self.ctx, EVP_CTRL_GCM_SET_TAG, self.mac_len, <unsigned char *> idata.buf+hlen):
if not EVP_CIPHER_CTX_ctrl(self.ctx, EVP_CTRL_AEAD_SET_TAG, self.mac_len, <unsigned char *> idata.buf + hlen):
raise CryptoError('EVP_CIPHER_CTX_ctrl SET TAG failed')
rc = EVP_DecryptUpdate(self.ctx, NULL, &olen, <const unsigned char*> idata.buf+aoffset, alen)
if not rc:
@ -597,7 +597,7 @@ cdef class _AEAD_BASE:
def next_iv(self):
# call this after encrypt() to get the next iv (int) for the next encrypt() call
# AES-GCM, AES-OCB, CHACHA20 ciphers all add a internal 32bit counter to the 96bit
# AES-OCB, CHACHA20 ciphers all add a internal 32bit counter to the 96bit
# (12 byte) IV we provide, thus we only need to increment the IV by 1.
iv = int.from_bytes(self.iv[:self.iv_len], byteorder='big')
return iv + 1