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add AES256 cypher decryption to support FIPS 140-3 #2101

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add AES256 cypher decryption to support FIPS 140-3 #2101

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285a2b9
fips changes
thperapp Aug 29, 2025
3903054
cleanup
thperapp Aug 29, 2025
1536ab0
Update HandlerUtil
thperapp Oct 10, 2025
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37 changes: 25 additions & 12 deletions AzureMonitorAgent/agent.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2714,19 +2714,32 @@ def get_settings():
'{0}.prv'.format(
settings_thumbprint))
decoded_settings = base64.standard_b64decode(encoded_settings)
decrypt_cmd = 'openssl smime -inform DER -decrypt -recip {0} ' \
'-inkey {1}'.format(encoded_cert_path,
encoded_key_path)

try:
session = subprocess.Popen([decrypt_cmd], shell = True,
stdin = subprocess.PIPE,
stderr = subprocess.STDOUT,
stdout = subprocess.PIPE)
output = session.communicate(decoded_settings)
except OSError:
pass
protected_settings_str = output[0]

# FIPS 140-3: use 'openssl cms' (supports AES256 & DES_EDE3_CBC) with fallback to legacy 'openssl smime'
cms_cmd = 'openssl cms -inform DER -decrypt -recip {0} -inkey {1}'.format(encoded_cert_path, encoded_key_path)
smime_cmd = 'openssl smime -inform DER -decrypt -recip {0} -inkey {1}'.format(encoded_cert_path, encoded_key_path)

protected_settings_str = None
for decrypt_cmd in [cms_cmd, smime_cmd]:
try:
session = subprocess.Popen([decrypt_cmd], shell=True,
stdin=subprocess.PIPE,
stderr=subprocess.STDOUT,
stdout=subprocess.PIPE)
output = session.communicate(decoded_settings)
# success only if return code is 0 and we have output
if session.returncode == 0 and output[0]:
protected_settings_str = output[0]
if decrypt_cmd == cms_cmd:
hutil_log_info('Decrypted protectedSettings using openssl cms.')
else:
hutil_log_info('Decrypted protectedSettings using openssl smime fallback.')
break
else:
hutil_log_info('Attempt to decrypt protectedSettings with "{0}" failed (rc={1}).'.format(decrypt_cmd, session.returncode))
except OSError:
pass

if protected_settings_str is None:
log_and_exit('Enable', GenericErrorCode, 'Failed decrypting protectedSettings')
Expand Down
36 changes: 29 additions & 7 deletions Utils/HandlerUtil.py
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,7 @@
import json
import time
import re
import subprocess
# imp was deprecated in python 3.12
if sys.version_info >= (3, 12):
import importlib
Expand Down Expand Up @@ -195,16 +196,37 @@ def _parse_config(self, ctxt):
cert = waagent.LibDir + '/' + thumb + '.crt'
pkey = waagent.LibDir + '/' + thumb + '.prv'
unencodedSettings = base64.standard_b64decode(protectedSettings)
openSSLcmd = "openssl smime -inform DER -decrypt -recip {0} -inkey {1}"
cleartxt = waagent.RunSendStdin(openSSLcmd.format(cert, pkey), unencodedSettings)[1]
if cleartxt is None:
self.error("OpenSSL decode error using thumbprint " + thumb)
self.do_exit(1, "Enable", 'error', '1', 'Failed to decrypt protectedSettings')

# FIPS 140-3: use 'openssl cms' (supports AES256 & DES_EDE3_CBC) with fallback to legacy 'openssl smime'
cms_cmd = 'openssl cms -inform DER -decrypt -recip {0} -inkey {1}'.format(cert,pkey)
smime_cmd = 'openssl smime -inform DER -decrypt -recip {0} -inkey {1}'.format(cert,pkey)

protected_settings_str = None
for decrypt_cmd in [cms_cmd, smime_cmd]:
try:
session = subprocess.Popen([decrypt_cmd], shell=True,
stdin=subprocess.PIPE,
stderr=subprocess.STDOUT,
stdout=subprocess.PIPE)
output = session.communicate(unencodedSettings)
# success only if return code is 0 and we have output
if session.returncode == 0 and output[0]:
protected_settings_str = output[0]
if decrypt_cmd == cms_cmd:
self.log('Decrypted protectedSettings using openssl cms.')
else:
self.log('Decrypted protectedSettings using openssl smime fallback.')
break
else:
self.log('Attempt to decrypt protectedSettings with "{0}" failed (rc={1}).'.format(decrypt_cmd, session.returncode))
except OSError:
pass

jctxt = ''
try:
jctxt = json.loads(cleartxt)
jctxt = json.loads(protected_settings_str)
except:
self.error('JSON exception decoding ' + HandlerUtility.redact_protected_settings(cleartxt))
self.error('JSON exception decoding ' + HandlerUtility.redact_protected_settings(protected_settings_str))
handlerSettings['protectedSettings']=jctxt
self.log('Config decoded correctly.')
return config
Expand Down