High level conclusions

Fuzzer fuzz_aead is blocked:

The runtime code coverage of fuzz_aead covers 0.0% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Fuzzer fuzz_dh is blocked:

The runtime code coverage of fuzz_dh covers 0.0% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Fuzzer fuzz_dsa is blocked:

The runtime code coverage of fuzz_dsa covers 21.42% of its statically reachable code. This means there is some place that blocks the fuzzer to continue exploring more code at run time.

Reachability and coverage overview

Functions statically reachable by fuzzers

31 / 919

Cyclomatic complexity statically reachable by fuzzers

99 / 2938

Runtime code coverage of functions

119 / 919

Warning: The number of runtime covered functions are larger than the number of reachable functions. This means that Fuzz Introspector found there are more functions covered at runtime than what is considered reachable based on the static analysis. This is a limitation in the analysis as anything covered at runtime is by definition reachable by the fuzzers.
This is likely due to a limitation in the static analysis. In this case, the count of functions covered at runtime is the true value, which means this is what should be considered "achieved" by the fuzzer.

Use the project functions table below to query all functions that were not covered at runtime.

The following table shows data about each function in the project. The functions included in this table correspond to all functions that exist in the executables of the fuzzers. As such, there may be functions that are from third-party libraries.

For further technical details on the meaning of columns in the below table, please see the Glossary .

Func name	Functions filename	Args	Function call depth	Reached by Fuzzers	Runtime reached by Fuzzers	Combined reached by Fuzzers	Fuzzers runtime hit	Func lines hit %	I Count	BB Count	Cyclomatic complexity	Functions reached	Reached by functions	Accumulated cyclomatic complexity	Undiscovered complexity

Fuzzer: fuzz_dsa

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	4	21.0%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	15	78.9%
All colors	19	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
2	5	cryptography.hazmat.primitives.asymmetric.dsa.generate_private_key	call site: 00005	private_key.public_key
1	12	...fuzz_dsa.TestInput	call site: 00012	cryptography.hazmat.primitives.asymmetric.utils.Prehashed.__init__
1	14	cryptography.hazmat.primitives.asymmetric.utils.Prehashed.__init__	call site: 00014	private_key.sign

Runtime coverage analysis

Covered functions

154

Functions that are reachable but not covered

11

Reachable functions

14

Percentage of reachable functions covered

21.43%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/	1
...fuzz_dsa	9
cryptography.hazmat.primitives.asymmetric.dsa	3
cryptography.hazmat.primitives.asymmetric.utils	1

Fuzzer: fuzz_dh

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	4	30.7%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	9	69.2%
All colors	13	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
2	0	EP	call site: 00000	atheris.FuzzedDataProvider
2	5	...fuzz_dh.TestInput	call site: 00005	peer_private_key.public_key

Runtime coverage analysis

Covered functions

154

Functions that are reachable but not covered

11

Reachable functions

11

Percentage of reachable functions covered

0.0%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/	1
...fuzz_dh	10

Fuzzer: fuzz_aead

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	0	0.0%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	14	100.%
All colors	14	100

Runtime coverage analysis

Covered functions

154

Functions that are reachable but not covered

11

Reachable functions

11

Percentage of reachable functions covered

0.0%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/	1
...fuzz_aead	10

Fuzzer: fuzz_sym

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	11	12.0%
gold	[1:9]	0	0.0%
yellow	[10:29]	0	0.0%
greenyellow	[30:49]	0	0.0%
lawngreen	50+	80	87.9%
All colors	91	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
2	1	...fuzz_sym.TestInput	call site: 00001	cryptography.fernet.Fernet.generate_key
2	54	cryptography.fernet.Fernet._get_unverified_token_data	call site: 00054	time.time
2	64	cryptography.hazmat.primitives.ciphers.base.Cipher.decryptor	call site: 00064	cryptography.hazmat.primitives.ciphers.algorithms.AES.__init__
1	5	cryptography.fernet.Fernet.generate_key	call site: 00005	cryptography.fernet.Fernet.__init__
1	34	cryptography.hazmat.primitives.ciphers.base.Cipher.encryptor	call site: 00034	cryptography.hazmat.primitives.ciphers.algorithms.AES.__init__
1	39	cryptography.hazmat.primitives._cipheralgorithm._verify_key_size	call site: 00039	cryptography.hazmat.primitives.ciphers.modes.CBC.__init__
1	43	cryptography.fernet.Fernet._encrypt_from_parts	call site: 00043	current_time.to_bytes
1	79	cryptography.hazmat.backends.openssl.backend.Backend.hmac_supported	call site: 00079	.isinstance

Runtime coverage analysis

Covered functions

154

Functions that are reachable but not covered

31

Reachable functions

60

Percentage of reachable functions covered

48.33%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
/	1
...fuzz_sym	9
cryptography.fernet	35
cryptography.utils	2
cryptography.hazmat.primitives.padding	3
cryptography.hazmat.primitives.ciphers.base	5
cryptography.hazmat.primitives.ciphers.modes	5
cryptography.hazmat.primitives.ciphers.algorithms	1
cryptography.hazmat.primitives._cipheralgorithm	2
cryptography.hazmat.primitives.kdf.pbkdf2	3
cryptography.hazmat.backends.openssl.backend	4

Optimal target analysis

Remaining optimal interesting functions

The following table shows a list of functions that are optimal targets. Optimal targets are identified by finding the functions that in combination, yield a high code coverage.

Func name	Functions filename	Arg count	Args	Function depth	hitcount	instr count	bb count	cyclomatic complexity	Reachable functions	Incoming references	total cyclomatic complexity	Unreached complexity
cryptography.hazmat.primitives.serialization.ssh.SSHCertificateBuilder.sign	cryptography.hazmat.primitives.serialization.ssh	2	['N/A', 'N/A']	5	0	37	11	7	53	0	177	153
cryptography.hazmat.primitives.serialization.ssh.load_ssh_private_key	cryptography.hazmat.primitives.serialization.ssh	4	['N/A', 'N/A', 'N/A', 'N/A']	4	0	12	15	9	35	0	116	60
cryptography.x509.name._RFC4514NameParser._parse_na	cryptography.x509.name	1	['N/A']	4	0	1	2	4	18	3	62	53

Implementing fuzzers that target the above functions will improve reachability such that it becomes:

Functions statically reachable by fuzzers

64 / 919

Cyclomatic complexity statically reachable by fuzzers

224 / 2938

All functions overview

If you implement fuzzers for these functions, the status of all functions in the project will be:

Func name	Functions filename	Args	Function call depth	Reached by Fuzzers	Runtime reached by Fuzzers	Combined reached by Fuzzers	Fuzzers runtime hit	Func lines hit %	I Count	BB Count	Cyclomatic complexity	Functions reached	Reached by functions	Accumulated cyclomatic complexity	Undiscovered complexity

This sections provides heuristics that can be used as input to a fuzz engine when running a given fuzz target. The current focus is on providing input that is usable by libFuzzer.

/src/fuzz_dsa.py

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['cryptography.hazmat.primitives.asymmetric.dsa.generate_private_key', '...fuzz_dsa.TestInput', 'cryptography.hazmat.primitives.asymmetric.utils.Prehashed.__init__']

/src/fuzz_dh.py

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['...fuzz_dh.TestInput']

/src/fuzz_aead.py

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

/src/fuzz_sym.py

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['...fuzz_sym.TestInput', 'cryptography.fernet.Fernet._get_unverified_token_data', 'cryptography.hazmat.primitives.ciphers.base.Cipher.decryptor', 'cryptography.fernet.Fernet.generate_key', 'cryptography.hazmat.primitives.ciphers.base.Cipher.encryptor', 'cryptography.hazmat.primitives._cipheralgorithm._verify_key_size', 'cryptography.fernet.Fernet._encrypt_from_parts', 'cryptography.hazmat.backends.openssl.backend.Backend.hmac_supported']

This section shows analysis of runtime coverage data.

For futher technical details on how this section is generated, please see the Glossary .

Complex functions with low coverage

Func name	Function total lines	Lines covered at runtime	percentage covered	Reached by fuzzers
m.get	35	16	45.71%	['fuzz_aead', 'fuzz_dh', 'fuzz_dsa', 'fuzz_sym']

This section shows which files and directories are considered in this report. The main reason for showing this is fuzz introspector may include more code in the reasoning than is desired. This section helps identify if too many files/directories are included, e.g. third party code, which may be irrelevant for the threat model. In the event too much is included, fuzz introspector supports a configuration file that can exclude data from the report. See the following link for more information on how to create a config file: link

Files in report

Source file	Reached by	Covered by
	[]	[]
cryptography.hazmat.primitives.ciphers.aead	[]	[]
bcrypt	[]	[]
atheris	[]	[]
cryptography.hazmat.primitives	[]	[]
cryptography.hazmat.primitives.kdf.kbkdf	[]	[]
cryptography.hazmat.primitives.twofactor.totp	[]	[]
cryptography.hazmat.primitives._serialization	[]	[]
...fuzz_dsa	['fuzz_dsa']	[]
cryptography.hazmat.decrepit.ciphers.algorithms	[]	[]
cryptography.hazmat.primitives.kdf.hkdf	[]	[]
cryptography.hazmat.primitives.kdf.pbkdf2	['fuzz_sym']	[]
cryptography.hazmat.backends.openssl	[]	[]
cryptography.hazmat.decrepit	[]	[]
cryptography.hazmat.primitives._asymmetric	[]	[]
email	[]	[]
hashlib	[]	[]
cryptography.hazmat.primitives.serialization	[]	[]
cryptography.x509.name	[]	[]
...fuzz_aead	['fuzz_aead']	[]
cryptography.hazmat.backends.openssl.backend	['fuzz_sym']	[]
cryptography.hazmat.primitives.asymmetric.utils	['fuzz_dsa']	[]
types	[]	[]
cryptography.hazmat.primitives._cipheralgorithm	['fuzz_sym']	[]
cryptography.__about__	[]	[]
typing	[]	[]
cryptography.hazmat.primitives.keywrap	[]	[]
...fuzz_dh	['fuzz_dh']	[]
cryptography.hazmat.primitives.asymmetric.types	[]	[]
cryptography.x509.verification	[]	[]
threading	[]	[]
cryptography.hazmat.bindings	[]	[]
cryptography.hazmat.primitives.kdf.concatkdf	[]	[]
cryptography.hazmat.primitives.hashes	[]	[]
cryptography.hazmat.primitives.kdf	[]	[]
	[]	[]
binascii	[]	[]
cryptography.hazmat.primitives.twofactor.hotp	[]	[]
cryptography.hazmat.primitives.ciphers.base	['fuzz_sym']	[]
cryptography.hazmat.primitives.asymmetric.dh	[]	[]
cryptography.hazmat.primitives.serialization.pkcs7	[]	[]
cryptography.hazmat.primitives.cmac	[]	[]
cryptography	[]	[]
cryptography.hazmat.primitives.asymmetric.padding	[]	[]
cryptography.hazmat.primitives.asymmetric.rsa	[]	[]
cryptography.fernet	['fuzz_sym']	[]
cryptography.hazmat.primitives.hmac	[]	[]
io	[]	[]
cryptography.hazmat.primitives.asymmetric.ed448	[]	[]
cryptography.hazmat.primitives.asymmetric	[]	[]
hmac	[]	[]
cryptography.hazmat.primitives.asymmetric.ed25519	[]	[]
cryptography.hazmat.primitives.poly1305	[]	[]
warnings	[]	[]
...fuzz_sym	['fuzz_sym']	[]
cryptography.hazmat.primitives.ciphers.modes	['fuzz_sym']	[]
cryptography.x509.general_name	[]	[]
cryptography.utils	['fuzz_sym']	[]
cryptography.hazmat.bindings._rust	[]	[]
cryptography.hazmat.primitives.serialization.base	[]	[]
cryptography.x509.extensions	[]	[]
cryptography.hazmat.backends	[]	[]
urllib	[]	[]
cryptography.hazmat.primitives.kdf.scrypt	[]	[]
time	[]	[]
cryptography.hazmat.bindings.openssl	[]	[]
cryptography.x509.oid	[]	[]
cryptography.hazmat.primitives.kdf.argon2	[]	[]
cryptography.hazmat._oid	[]	[]
cryptography.hazmat.primitives.twofactor	[]	[]
cryptography.x509.ocsp	[]	[]
cryptography.hazmat.primitives.kdf.x963kdf	[]	[]
math	[]	[]
cryptography.hazmat.bindings.openssl._conditional	[]	[]
cryptography.x509.base	[]	[]
cryptography.hazmat.primitives.asymmetric.ec	[]	[]
os	[]	[]
cryptography.hazmat.primitives.asymmetric.x448	[]	[]
datetime	[]	[]
base64	[]	[]
cryptography.hazmat.primitives.asymmetric.dsa	['fuzz_dsa']	[]
cryptography.hazmat.primitives.asymmetric.x25519	[]	[]
cryptography.hazmat.primitives.serialization.ssh	[]	[]
cryptography.x509.certificate_transparency	[]	[]
cryptography.hazmat.primitives.serialization.pkcs12	[]	[]
cryptography.hazmat	[]	[]
cryptography.hazmat.primitives.ciphers.algorithms	['fuzz_sym']	[]
random	[]	[]
cryptography.hazmat.decrepit.ciphers	[]	[]
cryptography.exceptions	[]	[]
re	[]	[]
cryptography.hazmat.primitives.padding	['fuzz_sym']	[]
cryptography.hazmat.primitives.ciphers	[]	[]
cryptography.hazmat.bindings.openssl.binding	[]	[]
cryptography.x509	[]	[]
cryptography.hazmat.primitives.constant_time	[]	[]

Directories in report

Directory