CLI Options

The certoraRun utility invokes the Solidity compiler and afterwards sends the job to Certora’s servers.

The most commonly used command is:

certoraRun contractFile:contractName --verify contractName:specFile

If contractFile is named contractName.sol, the run command can be simplified to

certoraRun contractFile --verify contractName:specFile

A short summary of these options can be seen by invoking certoraRun --help

For larger projects, the command line for running the Certora Prover can become large and cumbersome. It is therefore recommended to use configuration files instead. These are JSON5 files (with .conf extension) that hold the parameters and options for the Prover. See Configuration (Conf) Files for more information.

Most frequently used options

--verify

Usage

--verify <contract>:<spec_file>

What does it do? It runs formal verification of properties specified in a .spec file on a given contract. Each contract must have been declared in the input files or have the same name as the source code file it is in.

When to use it? When you wish to prove properties on the source code. This is by far the most common mode of the tool.

Example If we have a Solidity file Bank.sol, with a contract named Bank inside it, and a specification file called Bank.spec, the run command would be:

certoraRun Bank.sol --verify Bank:Bank.spec

--msg

Usage

--msg <description>

What does it do? Adds a message description to your run, similar to a commit message. This message will appear in the title of the completion email sent to you.

Note

You need to wrap your message in quotes if it contains spaces.

When to use it? Adding a message makes it easier to track several runs on the Prover Dashboard. It is very useful if you are running many verifications simultaneously. It is also helpful to keep track of a single file verification status over time, so we recommend always providing an informative message.

Example To create the message above, we used

certoraRun Bank.sol --verify Bank:Bank.spec --msg 'Removed an assertion'

--rule

Usage

--rule <rule_name_pattern>...

What does it do? Formally verifies one or more given properties instead of the whole specification file. An invariant can also be selected.

When to use it? This option saves a lot of run time. Use it whenever you care about only a specific subset of a specification’s properties. The most common case is when you add a new rule to an existing specification. The other is when code changes cause a specific rule to fail; in the process of fixing the code, updating the rule, and understanding counterexamples, you likely want to verify only that specific rule.

One can either specify a specific rule name, or use pattern matching with a *.

You can specify this flag multiple times to filter in several rules or rule patterns.

Example If Bank.spec includes the following properties:

invariant address_zero_cannot_become_an_account()
rule withdraw_succeeds()
rule withdraw_fails()

If we want to verify only withdraw_succeeds, we run

certoraRun Bank.sol --verify Bank:Bank.spec --rule withdraw_succeeds

If we want to verify both withdraw_succeeds and withdraw_fails, we run

certoraRun Bank.sol --verify Bank:Bank.spec --rule withdraw_succeeds withdraw_fails

Alternatively, to verify both withdraw_succeeds and withdraw_fails, we could simply run

certoraRun Bank.sol --verify Bank:Bank.spec --rule withdraw*

--exclude_rule

Usage

--exclude_rule <rule_name_pattern>...

What does it do? This flag is the opposite of --rule - it allows you to specify a list of rules that should not be run.

You can specify this flag multiple times to filter out several rules or rule patterns.

When to use it? Use this flag when certain rules take too long to run or require a different configuration than the current verification run.

Example If Bank.spec includes the following properties:

invariant address_zero_cannot_become_an_account()
rule withdraw_succeeds()
rule withdraw_fails()

If we want to skip both rules we could run

certoraRun Bank.sol --verify Bank:Bank.spec --exclude_rule withdraw*

--split_rules

Usage

--split_rules <rule_name_pattern>...

What does it do? Typically, all rules (after being filtered by --rule and --exclude_rule) are evaluated in a single Prover job. With --split_rules the user can run specific rules on separate dedicated Prover jobs. A new job will be created and executed for each rule that matches the rule patterns in --split_rules an additional job will be created for the rest of the rules. After launching the generated jobs, the original job will return with a link to the dashboard, listing the status of the generated jobs.

You can specify this flag multiple times to denote several rules or rule patterns.

When to use it? This option is useful when some rules take a much longer time than the rest. Split the difficult rules to their own dedicated Prover jobs will give them more resources that will potentially reduce their chance to timeout and will decrease the time to get the final job result for the less computationally intensive rules.

Example If Bank.spec includes the following properties:

invariant address_zero_cannot_become_an_account()
rule withdraw_succeeds()
rule withdraw_fails()

If we want to run the invariant on different Prover jobs we could run

certoraRun Bank.sol --verify Bank:Bank.spec --split_rules address_zero_cannot_become_an_account

The rest of the rules (withdraw_succeeds and withdraw_fails) will run together in a different Prover job.

Note

When used together with the --rule flag the logic is to collect all rules that pass the --rule flag(s) and then subtract from them all rules that match any --exclude_rule flag(s).

--method

Usage

--method <method_signature>...

What does it do? Only uses functions with the given method signature when instantiating parametric rules and invariants. The method signature is the ABI representation of the method, optionally prepended by a contract name or wildcard (_). If no contract is specified the primary contract is assumed, and if the wildcard is used then all methods with this signature across all contracts in the scene will be used.

You may provide multiple method signatures, in which case the Prover will run on each of the listed methods.

When to use it? This option is useful when focusing on a specific counterexample; running on a specific contract method saves time.

Example Suppose we are verifying an ERC20 contract, and we have the following parametric rule:

rule r {
    method f; env e; calldataarg args;
    address owner; address spender;

    mathint allowance_before = allowance(owner, spender);
    f(e,args);
    mathint allowance_after  = allowance(owner, spender);

    assert allowance_after > allowance_before => e.msg.sender == owner;
}

If we discover a counterexample in the method deposit(uint) of contract C, and wish to change the contract or the spec to rerun, we can just rerun on the C.deposit method:

certoraRun --method 'C.deposit(uint)'

If we discover a counterexample in several methods, we could rerun just those:

certoraRun --method 'deposit(uint)' --method '_.transfer(address,uint256)'

In the last example the transfer method of all contracts in the scene will be used, but only the deposit method of the primary contract.

Note

Many shells will interpret the ( and ) characters specially, so the method signature argument will usually need to be quoted as in the example.

--parametric_contracts

Added in version 5.0: Prior to version 5, method variables and invariants were only instantiated with methods of Special variables and fields.

Usage

--parametric_contracts <contract_name>...

What does it do? Only uses methods on the specified contract when instantiating parametric rules or invariants. The contract name must be one of the contracts included in the scene.

When to use it? As with the --rule and --method options, this option is used to avoid rerunning the entire verification

Example Suppose you are working on a multicontract verification and wish to debug a counterexample in a method of the Underlying contract defined in the file Example.sol:

certoraRun Main:Example.sol Underlying:Example.sol --verify Main:Example.spec \
    --parametric_contracts Underlying

--wait_for_results

What does it do? Wait for verification results after sending the verification request. By default, the program exits after the request. The return code will not be zero if the verification finds a violation.

When to use it? Use it to receive verification results in the terminal or a wrapping script.

In CI, the default behavior is different: the Prover waits for verification results, and the return code will not be zero if a violation is found. You can force the Prover not to wait for verification results by using --wait_for_results NONE. In that case, the return code will be zero if the jobs were sent successfully.

Example

certoraRun Example.sol --verify Example:Example.spec --wait_for_results

Options affecting the type of verification run

--coverage_info

Usage

--coverage_info <none|basic|advanced>

What does it do? This option enables .sol and .spec coverage analysis and visualization. The --coverage_info option may be followed by one of none, basic, or advanced; See Coverage Info for more information about the analysis.

When to use it? We suggest using this option when you have finished (a subset of) your rules and the prover verified them. The analysis tells you which parts of the solidity input are covered by the rules, and also which parts of the rules are actually needed to prove the rules.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --coverage_info advanced

--foundry

What does it do? Collects all test files in the project (files ending with .t.sol), and runs the Foundry Integration (Alpha) on them (specifically, the verifyFoundryFuzzTestsNoRevert builtin rule). As with the --project_sanity option, the search is over files in the current git repository if such exists, otherwise over all files in the tree under the current working directory.

Note

This option implicitly enables the --auto_dispatcher option.

When to use it? When we want to run all foundry fuzz tests in the project with the prover.

Example

certoraRun --foundry

--independent_satisfy

What does it do? The independent satisfy mode checks each satisfy statement independently from all other satisfy statements that occurs in a rule. Normally, each satisfy statement will be turned into a sub-rule (similarly to the --multi_assert_check mode), but previously encountered satisfy statements will be still considered when creating a satisfying assignment.

As an illustrative example of the default mode, consider the following rule R that has two satisfy statements:

rule R {
  bool b;
  satisfy b, "R1";
  satisfy !b, "R2";
}

The statements for “R1” and “R2” will actually create two sub-rules equivalent to:

rule R1_default {
  bool b;
  satisfy b, "R1";
}

rule R2_default {
  bool b;
  // Previous satisfy statements are required in default mode.
  require b; // R1
  // Due to requiring `b`, this satisfy statement is equivalent to 'satisfy b && !b, "R2";'
  satisfy !b, "R2";
}

Without turning independent_satisfy mode on, R2 would have failed, as it would try to satisfy b && !b, an unsatisfiable contradiction. Turning on the independent_satisfy mode will ignore all currently unchecked satisfy statements for each sub-rule. It would also generate and check two sub-rules, but with a slight difference: R1 where b is satisfied (by b=true) while satisfy !b is removed, and R2 where satisfy b is removed, and !b is satisfied (by b=false).

The two independent_satisfy generated sub-rules will be equivalent to:

rule R1_independent {
  bool b;
  satisfy b, "R1";
}

rule R2_independent {
  bool b;
  // require b;
  satisfy !b, "R2";
}

When to use it? When you have a rule with multiple satisfy statements, and you would like to demonstrate each statement separately.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --independent_satisfy

--multi_assert_check

What does it do? This mode checks each assertion statement that occurs in a rule, separately. The check is done by decomposing each rule into multiple sub-rules, each of which checks one assertion, while it assumes all preceding assertions. In addition, all assertions that originate from the Solidity code (as opposed to those from the specification), are checked together by a designated, single sub-rule.

As an illustrative example, consider the following rule R that has two assertions:

...
assert a1
...
assert a2
...

The multi_assert_check mode would generate and check two sub-rules: R1 where a1 is proved while a2 is removed, and R2 where a1 is assumed (i.e., transformed into a requirement statement), and a2 is proved.

R passes if and only if, R1 and R2 both pass. In particular, in case R1 (resp. R2) fails, the counter-example shows a violation of a1 (resp. a2).

Caution

We suggest using this mode carefully. In general, as this mode generates and checks more rules, it may lead to worse running-time performance. Please see indications for use below.

When to use it? When you have a rule with multiple assertions:

1. As a timeout mitigation strategy: checking each assertion separately may, in some cases, perform better than checking all the assertions together and consequently solve timeouts.

2. If you wish to get multiple counter-examples in a single run of the tool, where each counter-example violates a different assertion in the rule.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --multi_assert_check

--project_sanity

What does it do? Runs the builtin sanity rule on all methods in the project. If the Prover is run from within a git project, all .sol files in the in the git repository are added to the scene and the builtin sanity rule is run on them. Otherwise, all .sol files in the tree under the current working directory are collected.

Alternatively, a list of files can be provided in the .conf file and then the builtin sanity rule will run on all methods of the specified files.

Note

This option implicitly enables the --auto_dispatcher option.

When to use it? Mostly used as a first step when starting to work on a new project, in order to “get a feeling” of the complexity of the project for the tool, and what methods may be hot spots for summarization etc.

Example

certoraRun --project_sanity

--rule_sanity

Usage

--rule_sanity <none|basic|advanced>

What does it do? This option enables sanity checking for rules. The --rule_sanity option may be followed by one of none, basic, or advanced; See Rule Sanity Checks for more information about sanity checks.

When to use it? We suggest using this option routinely while developing rules. It is also a useful check if you notice rules passing surprisingly quickly or easily.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --rule_sanity basic

--short_output

What does it do? Reduces the verbosity of the tool.

When to use it? When we do not care much for the output. It is recommended when running the tool in continuous integration.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --short_output

Options that control the Solidity compiler

--compiler_map

Usage

--compiler_map <contract>=<version>,...

What does it do? Compiles every smart contract with a different compiler executable (Solidity version or Vyper). All used contracts must be listed.

When to use it? When different contracts have to be compiled for different Solidity versions.

Example

certoraRun Bank.sol Exchange.sol Token.vy --verify Bank:Bank.spec --compiler_map Bank=solc4.25,Exchange=solc6.7,Token=vyper0.3.10

--packages

Usage

--packages <name>=<path>...

What does it do? For each package, gets the path to a directory including that Solidity package.

When to use it? By default we look for the packages in $NODE_PATH. If there are packages are in several different directories, use --packages.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --packages ds-stop=$PWD/lib/ds-token/lib/ds-stop/src ds-note=$PWD/lib/ds-token/lib/ds-stop/lib/ds-note/src

--packages_path

Usage

--packages_path <path>

What does it do? Gets the path to a directory including the Solidity packages.

When to use it? By default, we look for the packages in $NODE_PATH. If the packages are in any other directory, you must use --packages_path.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --packages_path Solidity/packages

--solc

Usage

--solc <solc_executable>

What does it do? Use this option to provide a path to the Solidity compiler executable file. We check in all directories in the $PATH environment variable for an executable with this name. If --solc is not used, we look for an executable called solc, or solc.exe on windows platforms.

When to use it? Whenever you want to use a Solidity compiler executable with a non-default name. This is usually used when you have several Solidity compiler executable versions you switch between.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --solc solc8.1

--solc_allow_path

Usage

--solc_allow_path <path>

What does it do? Passes the value of this option as is to the solidity compiler’s option --allow-paths. See –allow-path specification

When to use it? When we want to add an additional location the Solidity compiler to load sources from

Example

certoraRun Bank.sol --verify Bank:Bank.spec --solc_allow_path ~/Projects/Bank

--solc_evm_version

Usage

--solc_evm_version <version>

What does it do? Passes the value of this option to the solidity compiler’s option --evm-version.

When to use it? When we want to select the Solidity compiler EVM version

Example

certoraRun Bank.sol --verify Bank:Bank.spec --solc_evm_version Istanbul

--solc_evm_version_map

Usage

--solc_evm_version_map <contract>=<version>,...

What does it do? Set EVM version values when different files run with different EVM versions Passes the value of this option as is to the solidity compiler’s option --evm-version.

When to use it? When different contracts have to be compiled with different Solidity EVM versions.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --solc_evm_version_map Bank=prague,Exchange=cancun

--solc_optimize

Usage

--solc_optimize <n>

What does it do? Passes the value of this option as is to the solidity compiler’s option --optimize and --optimize-runs.

When to use it? When we want to activate in the solidity compiler the opcode-based optimizer for the generated bytecode and control the number of times the optimizer will be activated (if no value is set, the compiler’s default is 200 runs)

Example

certoraRun Bank.sol --verify Bank:Bank.spec --solc_optimize 300

--solc_optimize_map

Usage

--solc_optimize_map <contract>=<n>,...

What does it do? Set optimize values when different files run with different number of runs Passes the value of this option as is to the solidity compiler’s option --optimize and --optimize-runs.

When to use it? When we want to activate in the solidity compiler the opcode-based optimizer for the generated bytecode and control the number of times the optimizer will be activated (if no value is set, the compiler’s default is 200 runs)

Example

certoraRun Bank.sol --verify Bank:Bank.spec --solc_optimize_map Bank=200,Exchange=300

--solc_via_ir

What does it do? Passes the value of this option to the solidity compiler’s option --via-ir.

When to use it? When we want to enable the IR-based code generator

Example

certoraRun Bank.sol --verify Bank:Bank.spec --solc_via_ir

Options regarding source code loops

--loop_iter

Usage

--loop_iter <n>

What does it do? Sets the maximal number of loop iterations we verify for. The way the Certora Prover handles loops is by unrolling them - if the loop should be executed three times, it will copy the code inside the loop three times. This option sets the number of unrolls. Be aware that the run time grows exponentially by the number of loop iterations.

When to use it? The default number of loop iterations we unroll is one. However, in many cases, bugs only occur when there are several iterations. Common scenarios include iteration over list elements. Two, or in some cases three, is usually the most you will ever need to uncover bugs.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --loop_iter 2

--optimistic_loop

What does it do? The Certora Prover unrolls loops - if the loop should be executed three times, it will copy the code inside the loop three times. After we finish the loop’s iterations, we add an assertion to verify we have actually finished running the loop. For example, in a while (a < b) loop, after the loop’s unrolling, we add assert a >= b. We call this assertion the loop unwind condition. This option changes the assertions of the loop unwind condition to requirements (in the case above require a >= b). That means, we ignore all the cases where the loop unwind condition does not hold, instead of considering them as a failure.

When to use it? When you have loops in your code and are getting a counterexample labeled loop unwind condition. In general, you need this flag whenever the number of loop iterations varies. It is usually a necessity if using --loop_iter.

Caution

--optimistic_loop could cause vacuous rules.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --optimistic_loop

Options regarding summarization

--auto_dispatcher

What does it do? In case a call’s callee cannot be precomputed but the called method’s sighash can be (e.g. MyInterface(addr).foo() in solidity, where addr is some address typed variable), the default behavior of the Prover in this case is to Havoc. In this case the user can specify a DISPATCHER summaries summary in the The Methods Block so that the prover will inline all methods in the scene that have this sighash.

This option will cause all such unknown callee with known sighash cases to behave as if an DISPATCHER(optimistic=true) was added for that method in the methods block.

One important difference from manually placing the DISPATCHER summary in the methods block is that when it’s manually written there with optimistic=true and no such function is found in the scene the Prover will exit with an error, but when using the flag it will fall back to the default havoc.

When to use it? When there are many unresolved callee methods, or as a first step to solve call resolution failures.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --auto_dispatcher

--nondet_difficult_funcs

What does it do? When this option is set, the Prover will auto-summarize view or pure internal functions that return a value type and are currently not summarized, and that are found to be heuristically difficult for the Prover.

For more information, see Detect candidates for summarization.

When to use it? Using this option is recommended when beginning to work on a large code base that includes functions that could be difficult for the Prover. It can help the user get faster feedback, both in the form of faster verification results, as well as highlighting potentially difficult functions.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --nondet_difficult_funcs

--nondet_minimal_difficulty

Usage

--nondet_minimal_difficulty <n>

What does it do? This option sets the minimal difficulty threshold for the auto-summarization mode enabled by --nondet_difficult_funcs.

When to use it? If the results of an initial run with --nondet_difficult_funcs were unsatisfactory, one can adjust the default threshold to apply the auto-summarization to potentially more or fewer internal functions.

The notification in the rule report that contains the applied summaries will present the current threshold used by the Prover.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --nondet_difficult_funcs --nondet_minimal_difficulty 20

--optimistic_summary_recursion

What does it do? In case there’s a call to some Solidity function within a summary, we may end up with recursive calls to this summary. For example, if in the summary of foo we call the Solidity function bar, and bar’s Solidity code contains a call to foo, we’ll summarize foo again, which will lead to another call to bar etc. In this case if this flag is set to false we may get an assertion failure with a message along the lines of

Recursion limit (...) for calls to ..., reached during compilation of summary ...

Such recursion can also happen with dispatcher summaries — if a contract method f makes an unresolved external call to a different method f, and if f is summarized with a DISPATCHER summary, then the Prover will consider paths where f recursively calls itself. Without --optimistic_summary_recursion, the Prover may report a rule violation with the following assert message:

When summarizing a call with dispatcher, found we already have it in the stack: ... consider removing its dispatcher summary.

The default behavior in this case is to assert that the recursion limit is not reached (the limit is controlled by the --summary_recursion_limit flag). With --optimistic_summary_recursion, the Prover will instead assume that the limit is never reached.

When to use it? Use this flag when there is recursion due to summaries calling Solidity functions, and this causes an undesired assertion failure. In this case one can either make the limit larger (via --summary_recursion_limit) or set this flag to true.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --optimistic_summary_recursion

Caution

This flag could cause unsoundness - even if such recursion could actually happen in the deployed contract, this code-path won’t be verified.

--summary_recursion_limit

Usage

--summary_recursion_limit <n>

What does it do? Summaries can cause recursion (see --optimistic_summary_recursion). This option sets the summary recursion level, which is the number of recursive calls that the Prover will consider.

If the Prover finds an execution in which a function is called recursively more than the contract recursion limit, the Prover will report an assertion failure (unless --optimistic_summary_recursion is set, in which case the execution will be ignored). The default value is zero (i.e. no recursion is allowed).

When to use it?

1. Use this option when there is recursion due to summaries calling Solidity functions, and this leads to an assertion failure. In this case one can either make the limit larger or set (via --optimistic_summary_recursion) flag to true.

2. Use it if you get the following assertion failure, and disabling optimistic fallback is not possible:

When inlining a fallback function, found it was already on the stack. Consider disabling optimistic fallback mode.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --summary_recursion_limit 3

Options regarding hashing of unbounded data

--optimistic_hashing

What does it do?

When hashing data of potentially unbounded length (including unbounded arrays, like bytes, uint[], etc.):

1. If optimistic_hashing is set the Proves assumes the data’s length is bounded by the --hashing_length_bound option.

2. If optimistic_hashing is not set, the Prover will check whether the data’s length can exceed the hashing_length_bound, and report an assertion violation if it can.

See Hashing of unbounded data for more details.

When to use it?

When the assertion regarding unbounded hashing is thrown, but it is acceptable for the Prover to ignore cases where the length hashed values exceeds the current bound.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --optimistic_hashing

--hashing_length_bound

Usage

--hashing_length_bound <n>

What does it do?

Constraint on the maximal length of otherwise unbounded data chunks that are being hashed. This constraint is either assumed or checked by the Prover, depending on whether --optimistic_hashing has been set. The bound is specified as a number of bytes.

The default value of this option is 224 (224 bytes correspond to 7 EVM machine words as 7 * 32 == 224).

When to use it? Reason to lower this value:

Lowering potentially improves SMT performance, especially if there are many occurrences of unbounded hashing in the program.

Reasons to raise this value:

• when --optimistic_hashing is not set: avoid the assertion being violated when the hashed values are actually bounded, but by a bound that is higher than the default value (in case of --optimistic_hashing being not set)

• when --optimistic_hashing is set: find bugs that rely on a hashed array being at least of that length. (Optimistic hashing excludes all cases from the scope of verification where something being hashed is longer than this bound.)

Example

certoraRun Bank.sol --verify Bank:Bank.spec --hashing_length_bound 128

Options that help reduce the running time

--compilation_steps_only

What does it do? Exits the program after source code and spec compilation without sending a verification request to the cloud.

When to use it? Use it to check if the spec has correct syntax but do not wish to send a verification request and wait for its results.

Here are a few example scenarios:

1. When writing hooks, ghosts, summaries, or CVL functions, you can verify the spec before continuing to write rules.

2. In CI, you can check CVL correctness after every PR but run the expensive and long verification only on nightly runs.

3. When you have no internet connection but still want to develop spec offline.

Example

certoraRun Example.sol --verify Example:Example.spec --compilation_steps_only

--disable_local_type_checking

What does it do?

This flag disables the local syntax and type checking of your CVL specifications before they are sent to the cloud for verification. When used, simple syntax or type errors will not be caught locally and will only become visible during the cloud run, potentially causing unnecessary delays and confusion.

When to use it?

This flag should only be used in rare cases when you believe the local syntax or type checking has produced an incorrect error, and you are confident that the specification is valid. Before using this flag, it is recommended to first attempt reinstalling the Prover by following the instructions in the Installation section. Using this flag is strongly discouraged as it bypasses an essential layer of error detection, increasing the likelihood of issues being encountered later during the verification process.

Example

certoraRun MyContract.sol --verify MyContract:MySpec --disable_local_typechecking

Caution

Avoid using this flag unless absolutely necessary. It is always better to fix syntax or type issues locally to ensure a smoother verification process.

--global_timeout

Usage

--global_timeout <seconds>

What does it do?

Sets the maximal timeout for the Prover. Gets an integer input, which represents seconds.

The Certora Prover is bound to run a maximal time of 2 hours (7200 seconds). Users may opt to set this number lower to facilitate faster iteration on specifications. Values larger than two hours (7200 seconds) are ignored.

Jobs that exceed the global timeout will simply be terminated, so the result reports may not be generated.

The global timeout is different from the --smt_timeout option: the --smt_timeout flag constrains the amount of time allocated to the processing of each individual rule, while the --global_timeout flag constrains the processing of the entire job, including static analysis and other preprocessing.

When to use it? When running on just a few rules, or when willing to make faster iterations on specs without waiting too long for the entire set of rules to complete.

Note

Even if in the shorter running time not all rules were processed, a second run may pull some results from cache, and therefore more results will be available.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --global_timeout 60

--method

See --method

--smt_timeout

Usage

--smt_timeout <seconds>

What does it do? Sets the maximal timeout for all the SMT solvers. Gets an integer input, which represents seconds.

The Certora Prover generates a logical formula from the specification and source code. Then, it passes it on to an array of SMT solvers. The time it can take for the SMT solvers to solve the equation is highly variable, and could potentially be infinite. This is why they must be limited in run time.

The SMT timeout applies separately to each individual rule (or each method for parametric rules). To set the global timeout, see --global_timeout.

Note

While this is the most prominent timeout, this is not the only timeout that applies to SMT solvers, for details see -mediumTimeout and Control flow splitting.

When to use it? The default time out for the solvers is 300 seconds. There are two use cases for this option. One is to decrease the timeout. This is useful for simple rules, that are solved quickly by the SMT solvers. Here, it is beneficial to reduce the timeout, so that when a new code breaks the specification, the tool will fail quickly. This is the more common use case. The second use is when the solvers can prove the property, they just need more time. Usually, if the rule isn’t solved in 600 seconds, it will not be solved in 2,000 either. It is better to concentrate your efforts on simplifying the rule, the source code, add more summaries, or use other time-saving options. The prime causes for an increase of --smt_timeout are rules that are solved quickly, but time out when you add a small change, such as a requirement, or changing a strict inequality to a weak inequality.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --smt_timeout 300

Options to set addresses and link contracts

--address

Usage

--address <contract>:<address>

What does it do? Sets the address of a contract to a given address.

When to use it? When we have an external contract with a constant address. By default, the Python script assigns addresses as it sees fit to contracts.

Example

If we wish the Oracle contract to be at address 12, we use

certoraRun Bank.sol Oracle.sol --verify Bank:Bank.spec --address Oracle:12

--contract_extensions

What does it do? In order to support extendability and upgradeability of smart contracts, the proxy pattern is used. In this patterns there is a base contract (the proxy) which delegate-calls into “extension” contracts (see e.g. https://docs.openzeppelin.com/upgrades-plugins/1.x/proxies for more details). This flag allows specifying that some contract is actually an extension of another one, to help the Prover analyze low-level calls and resolve them correctly in this case. In practice the Prover “moves” all the external function implementations from the extension contract into the base contract, which means that to access them from CVL one should use the base contract as the receiver, and not the extension contract.

When to use it? If you use the proxy pattern in your smart contracts.

Example Say we have a base contract A that uses an extension contract B. Since in this pattern the storage of the two contracts may “overlap”, let’s also assume they both have some uint public n. In the .conf file one should add

"contract_extensions": {
    "A": [
        {
            "extension": "B",
            "exclude": ["n"]
        }
    ]
}

This tells the prover that B is an extension contract of A, but that it shouldn’t “transfer” the getter for n from the extension into the base contract (since the base contract already has such a function and this would cause a conflict).

For a more detailed example click here.

--contract_recursion_limit

Usage

--contract_recursion_limit <n>

What does it do? Contract inlining can cause recursion (see --optimistic_contract_recursion). This option sets the contract recursion level, which is the number of recursive calls that the Prover will consider when inlining contracts linked using, e.g., --link or --struct_link.

Note

In this context, recursion refers to the state where the same external function appears twice in the call stack. Contracts can also exhibit recursive behavior due to recursive calls to internal functions, which is unrelated to this option.

If a counterexample causes a function to be called recursively more than the contract recursion limit, it will report an assertion failure (unless --optimistic_contract_recursion is set, in which case the counterexample will be ignored). The default value is zero (i.e., no recursion is allowed).

When to use it? Use this option when after linking the resulting program may have paths with recursive calls to external Solidity functions, and this leads to a recursion-specific assertion failure, showing the message Contract recursion limit reached. In this case one can either make the limit larger or set --optimistic_contract_recursion flag to true.

Note

Increasing the limit is not always sufficient, as the code may in fact allow theoretically unbounded recursion.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --contract_recursion_limit 3

--link

Usage

--struct_link <contract>:<slot>=<address>

What does it do? Links a slot in a contract with another contract.

When to use it? Many times a contract includes the address of another contract as one of its fields. If we do not use --link, it will be interpreted as any possible address, resulting in many nonsensical counterexamples.

Example Assume we have the contract Bank.sol with the following code snippet: IERC20 public underlyingToken;

We have a contract BankToken.sol, and underlyingToken should be its address. To do that, we use:

certoraRun Bank.sol BankToken.sol --verify Bank:Bank.spec --link Bank:underlyingToken=BankToken

--optimistic_contract_recursion

What does it do? Contract linking can cause recursion (see also --contract_recursion_limit). This option sets the Prover to optimistically assume that recursion cannot go beyond what is defined by --contract_recursion_limit, but only if --contract_recursion_limit is set to a number higher than 0.

When to use it?

1. When the recursion due to contract linking is unbounded.

2. When we are interested only in a limited recursion depth due to contract linking.

Caution

This flag could be another cause for unsoundness - even if such recursion could actually happen in the deployed contract, this code-path won’t be verified beyond the specified recursion limit (--contract_recursion_limit).

Example

certoraRun Bank.sol --verify Bank:Bank.spec --optimistic_contract_recursion true --contract_recursion_limit 1

--optimistic_fallback

What does it do?

This option controls how the Prover handles unresolved external calls with an empty input buffer (length 0). By default, such calls will havoc all storage state of external contracts. When --optimistic_fallback is enabled, these calls will instead:

• Execute the fallback function in the specified contract (if it exists).

• Revert if no fallback function is available.

• Execute a transfer if applicable.

This modifies the behavior of AUTO summaries by preventing unnecessary state havoc for empty input calls.

When to use it?

Enable this option to avoid spurious counter examples for external calls with empty input buffers.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --optimistic_fallback

--struct_link

Usage

--struct_link <contract>:<slot>=<address>

What does it do? Links a slot in a struct with another contract. To do that you must calculate the slot number of the field you wish to replace.

When to use it? Many times a contract includes the address of another contract inside a field of one of its structs. If we do not use --struct_link, it will be interpreted as any possible address, resulting in many nonsensical counterexamples.

Example Assume we have the contract Bank.sol with the following code snippet: TokenPair public tokenPair;

Where TokenPair is

struct TokenPair {
    IERC20 tokenA;
    IERC20 tokenB;
}

We have two contracts BankToken.sol and LoanToken.sol. We want tokenA of the tokenPair to be BankToken, and tokenB to be LoanToken. Addresses take up only one slot. We assume tokenPair is the first field of Bank (so it starts at slot zero). To do that, we use:

certoraRun Bank.sol BankToken.sol LoanToken.sol --verify Bank:Bank.spec --struct_link Bank:0=BankToken Bank:1=LoanToken

Options for controlling contract creation

--dynamic_bound

Usage

--dynamic_bound <n>

What does it do? If set to zero (the default), contract creation (via the new statement or the create/create2 instructions) will result in a havoc, like any other unresolved external call. If non-zero, then dynamic contract creation will be modeled with cloning, where each contract will be cloned at most n times.

When to use it? When you wish to model contract creation, that is, simulating the actual creation of the contract. Without it, create and create2 commands simply return a fresh address; the Prover does not model their storage, code, constructors, immutables, etc. Any interaction with these generated addresses is modeled imprecisely with conservative havoc.

Example Suppose a contract C creates a new instance of a contract Foo, and you wish to inline the constructor of Foo at the creation site.

certoraRun C.sol Foo.sol --verify C:C.spec --dynamic_bound 1

--dynamic_dispatch

What does it do? By default, contract method invocations on newly created instances remain unresolved, requiring explicit DISPATCHER summaries for all such method calls. With this option, the Prover will automatically apply the DISPATCHER summary on a best-effort basis for call sites where the receiver is proven to be a newly created contract.

Limitations

• This option only applies when the Prover can prove that the callee is a created contract.

• If a contract instance is assigned from both a newly created contract and another source (e.g., storage), calls will remain unresolved. For example:

MyFoo f;
if(*) {
   f = new MyFoo(...);
} else {
  f = storageStruct.myFoo;
}
f.bar();

When to use it? Use this flag when you prefer not to manually add explicit DISPATCHER summaries for methods invoked by the created contract.

Example Suppose a contract C creates a new instance of a contract Foo, and you wish to inline the constructor of Foo at the creation site, and Foo calls some method m() which you wish to automatically link to the newly created contract.

certoraRun C.sol Foo.sol --verify C:C.spec --dynamic_bound 1 --dynamic_dispatch

Note

You must also use the --dynamic_bound option.

--prototype

Usage

--prototype <hex string>=<contract>

What does it do? Instructs the Prover to use a specific contract type for the return value from a call to create or create2 on the given hexadecimal string as a prefix. The hexadecimal string represents proxy code that forwards calls to another contract. As we are using the prototype flag to skip calls to the proxy, no constructor code is being simulated for these contract creation resolutions.

When to use it? If you are verifying a contract creation that uses low level calls to create or create2 for contract creation.

Example Suppose you have a contract C that creates another contract Foo like this:

assembly {
     let ptr := mload(0x40)
     mstore(ptr, 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000000000000000000000)
     mstore(add(ptr, 0x14), shl(0x60, implementation))
     mstore(add(ptr, 0x28), 0x5af43d82803e903d91602b57fd5bf30000000000000000000000000000000000)
     instance := create(0, ptr, 0x37)
}

Then you can set the string 3d602d80600a3d3981f3363d3d373d3d3d363d73 appearing in the first mstore after the 0x prefix as a “prototype” for Foo. The Prover will then be able to create a new instance of Foo at the point where the code creates it:

certoraRun C.sol Foo.sol --verify C:C.spec --prototype 3d602d80600a3d3981f3363d3d373d3d3d363d73=Foo --dynamic_bound 1

Note

This argument has no effect if the dynamic bound is zero.

Note

The hex string must be:

• A strict prefix of the memory region passed to the create command.

• Must be unique within each invocation of the tool.

• Must not contain gaps, e.g., 3d602d80600a3d3981f3363d3d373d3d3d363d730000 in the above example will not work (those last four bytes will be overwritten) but 3d602d80600a3d3981f3363d3d373d3d3d363d will.

Version options

--version

What does it do? Shows the version of the local installation of the tool you have.

When to use it? When you suspect you have an old installation. To install the newest version, use pip install --upgrade certora-cli.

Example

certoraRun --version

Advanced options

--allow_solidity_calls_in_quantifiers

What does it do?

Instructs the Prover to permit contract method calls in quantified expression bodies.

When to use it?

Upon instruction from the Certora team.

Example

--allow_solidity_calls_in_quantifiers instructs the Prover to not generate an error on encountering contract method calls in quantified expression bodies.

--java_args

What does it do?

Allows setting configuring the underlying JVM.

When to use it?

Upon instruction from the Certora team.

Example

--java_args '"-Dcvt.default.parallelism=2"' - will set the number of “tasks” that can run in parallel to 2.

--precise_bitwise_ops

What does it do? This option models bitwise operations exactly, instead of using the default overapproximation. It is useful when the Prover reports a counterexample caused by incorrect modeling of bitwise operations, but enabling this option can significantly increase verification time.

Limitations

• This encoding does not model mathint precisely.

• The maximum supported integer value is \(2^{256} - 1\), effectively restricting mathint to a uint256.

• There is currently no encoding that precisely models both bitwise operations and mathint simultaneously.

When to use it? Use this option if a counterexample suggests that incorrect modeling of bitwise operations is affecting verification results.

Example

certoraRun Bank.sol --verify Bank:Bank.spec --precise_bitwise_ops

--prover_args

The --prover_args option allows you to provide fine-grained tuning options to the Prover. --prover_args receives a string containing Prover-specific options, and will be sent as-is to the Prover. --prover_args cannot set Prover options that are set by standalone certoraRun options (e.g. the Prover option --t is set by --smt_timeout therefore cannot appear in --prover_args). --prover_args value must be quoted.

-enableStorageSplitting

This option disables the storage splitting optimization.

Usage

--prover_args '-enableStorageSplitting false'

-maxNumberOfReachChecksBasedOnDomination

This option sets the number of program points to test with the deepSanity built-in rule. See Thorough complexity checks — deepSanity.

Usage

--prover_args '-maxNumberOfReachChecksBasedOnDomination <n>'

-optimisticReturnsize

This option determines whether havoc summaries assume that the called method returns the correct number of return values. It will set the value returned by the RETURNSIZE EVM instruction according to the called method.

Note

Certain conditions should hold in order for the option to take effect. Namely, if there is a single candidate method in the havoc site, and all instances of this method in the scene have exactly the same expected number of return values, then the RETURNSIZE value will be set to the expected size matching the methods in the scene. Otherwise, RETURNSIZE will remain non-deterministic.

Usage

--prover_args '-optimisticReturnsize true'

-smt_groundQuantifiers

This option disables quantifier grounding. See Quantifier Grounding for more information.

Usage

--prover_args '-smt_groundQuantifiers false'

-superOptimisticReturnsize

This option determines whether havoc summaries assume that the called method returns the correct number of return values. It will set the value returned by the RETURNSIZE EVM instruction to the size of the output buffer as specified by the summarized CALL instruction.

Usage

--prover_args '-superOptimisticReturnsize true'

Control flow splitting options

See here for an explanation of control flow splitting.

-depth

Usage

--prover_args '-depth <number>'

What does it do?

Sets the maximum splitting depth.

When to use it?

When the deepest splits are too heavy to solve, but not too high in number, increasing this will lead to smaller, but more numerous split leaves, which run at the full SMT timeout (as set by --smt_timeout). Conversely, if run time is too high because there are too many splits, decreasing this number means that more time is spent on fewer, but bigger split leaves. The default value for this option is 10.

Example

certoraRun Bank.sol --verify Bank:bank.spec --prover_args '-depth 5'

-dontStopAtFirstSplitTimeout

Usage

--prover_args '-dontStopAtFirstSplitTimeout <true/false>'

What does it do?

We can tell the Certora Prover to continue even when the a split has had a maximum-depth timeout. Note that this is only useful when there exists a counterexample for the rule under verification, since in order to prove the absence of counterexamples (i.e. correctness), all splits need to be counterexample-free. (In case of a rule using satisfy rather than assert, the corresponding statements hold for witness examples. In that case, this option is only useful if the rule is correct.)

When to use it?

When looking for a SAT result and observing an SMT-type timeout. The default value for this option is false.

Example

certoraRun Bank.sol --verify Bank:bank.spec --prover_args '-dontStopAtFirstSplitTimeout true'

-mediumTimeout

The “medium timeout” determines how much time the SMT solver gets for checking a split that is not a split leaf. (For split leaves, the full --smt_timeout is used.)

Usage

--prover_args '-mediumTimeout <seconds>'

What does it do?

Sets the time that non-leaf splits get before being split again.

When to use it?

When a little more time can close some splitting subtrees early, this can save a lot of time, since the subtree’s size is exponential in the remaining depth. On the other hand, if something will be split further anyway, this can save the run time spent on intermediate “TIMEOUT” results. Use -smt_initialSplitDepth to eliminate that time investment altogether up to a given depth.

Example

certoraRun Bank.sol --verify Bank:bank.spec --prover_args '-mediumTimeout 20'

-smt_initialSplitDepth

With this option, the splitting can be configured to skip the SMT solver-based checks at low splitting levels, thus generating sub-splits up to a given depth immediately.

Usage

--prover_args '-smt_initialSplitDepth <number>'

What does it do?

The first <number> split levels are not checked with the SMT solver, but rather split immediately.

When to use it?

When there is a lot of overhead induced by processing and trying to solve splits that are very hard, and thus run into a timeout anyway.

Note

The number of splits generated here is equal to \(2^n\) where n is the initial splitting depth (assuming the program has enough branching points, which is usually the case); thus, low numbers are advisable. For instance setting this to 5 means that the Prover will immediately produce 32 splits.

Note

The -depth setting has precedence over this setting. I.e., if -depth is set to a lower value than -smt_initialSplitDepth, the initial splitting will only proceed up to the splitting depth given via -depth.

Example

certoraRun Bank.sol --verify Bank:bank.spec --prover_args '-smt_initialSplitDepth 3'