prova drives ISO 20022, ISO 8583 and FIX at a payment host, card switch or trading venue, and proves whether it behaved as it must. A well-formed approval of a payment the account cannot cover is still a defect. prova finds it, names the rule it breaks and cites the evidence, and an independent SAT-backed check and a second rules engine confirm the verdict. It is not an AI explanation; nothing in prova guesses.
One 39 MB program. The web console, the reference manual, the database, the whole ISO 20022 catalogue, 1,745 scenarios, 32 suites and twelve simulated targets are built in. Copy it, run it, open the browser.
Sign in as demo with password try-prova-now · simulated targets only · look at everything, change nothing
Download v0.4.0 for Linux · macOS, Apple Silicon · Windows — one file, nothing to install
Why prova · What it does · What it looks like · Running it · How it compares · Security · FAQ
prova is a test and proof harness for the systems that move money. It sends real wire messages — a pacs.008 credit transfer, an ISO 8583 0100 authorisation, a FIX NewOrderSingle — to the system under test, reads what comes back, and decides whether that answer was right given what was known: the balance, the account's currency, the instruction already processed, the value date.
The verdict is pass, fail or indeterminate, and it comes with its proof. Each verdict is decided by formal argumentation over the evidence of the exchange under grounded semantics. The Proof screen shows the argument graph, the cited chain of steps, a certificate from an independent re-check (C++ and CaDiCaL), and the verdict of a second, separately written rules engine. When the evidence does not decide it, prova says so and names what would.
It is built for the people who sign off. A release manager who needs more than "the tests passed", an auditor working to PCI DSS or SOX, a migration lead moving from SWIFT MT to ISO 20022 before the CBPR+ coexistence period ends: each gets a record of every verdict, who ran it, and why it holds, kept in prova's database and exportable as CSV.
Every payment and trading system is tested with simulators and format validators. They answer one question — did the response look right? — and miss the defects that matter:
- a host that approves a payment larger than the balance returns a perfectly valid
ACSC; - a switch that processes the same instruction twice returns two valid confirmations;
- a venue that fills an order over buying power returns a valid ExecutionReport.
prova asks the second question: was that the right answer? It ships simulated targets with exactly these planted defects, so the first ten minutes show prova catching them.
Protocols
- ISO 20022 — credit transfers (pacs.008, pacs.009), direct debits under mandates (pacs.003, pacs.010), returns (pacs.004), cancellations (camt.056, answered by camt.029), status requests (pacs.028), customer initiations (pain.001, answered by pain.002) and account reporting (camt.060, answered by a camt.052, camt.053 or camt.054 report or an admi.002 reject). Every message prova sends is valid against the official schema, and so is every reply its simulated host gives.
- ISO 8583 — 0100 authorisations, 0200 purchases, 0400 reversals and 0800 network management in three wire dialects: generic ASCII, a Visa-style dialect (BCD, EBCDIC, binary bitmaps and fields, the 22-byte BASE I header) and a Mastercard-style dialect (EBCDIC, binary bitmaps and fields). The dialect codecs agree byte for byte with pyiso8583.
- FIX 4.2, 4.4 and 5.0 SP2 — tag=value with BodyLength and CheckSum; the session layer over FIX.4.2, FIX.4.4 and FIXT.1.1, with the session rules a venue must enforce (sequence numbers, possible duplicates, comp ids, garbled messages, gap recovery); NewOrderSingle, cancel, replace, status and order mass cancel, answered by ExecutionReport (fills and partial fills), OrderCancelReject, OrderMassCancelReport, session Reject or Logout.
- Card security — ISO 9564 PIN blocks (formats 0, 1, 3 and AES format 4), ISO 9797-1 MACs and AES-CMAC, EMV cryptograms (Visa CVN 10 and 18, Mastercard CVN 16), Visa PVV and CVV. prova verifies them under seeded test keys, so a switch that approves a wrong PIN or a counterfeit chip is provably at fault. Checked against psec, pyemv and RFC 4493.
- HSMs — a client for the Thales payShield host commands (diagnostics, PIN translation, PIN verification against a PVV, CVV verification), tested against the pythales simulator:
prova hsm, or the Card security screen. - The whole ISO 20022 catalogue — all 2,641 published schemas (707 messages in 31 business areas: payments, cash, securities, cards, trade, FX, reference data) ship inside the binary. Any message validates, gets a generated valid sample or a deliberately broken variant, and can be sent to a gateway that must acknowledge it (admi.007) or reject it (admi.002). The validator agrees with libxml2 on all 38,428 catalogue test cases.
- Message validation — the official schema, then a usage-guideline profile (CBPR+, SEPA Credit Transfer, SEPA Instant, FedNow), then a usage-guideline schema from the library (TCH RTP bundled; import your own XSD or a MyStandards or EPC ZIP). Findings name the rule, field and fix, and export as SARIF.
- MT ↔ MX — MT103 ↔ pacs.008, MT202 ↔ pacs.009, MT103 RETN ↔ pacs.004, MT192 ↔ camt.056, MT196 ↔ camt.029, MT900 and MT910 ↔ camt.054, MT940 ↔ camt.053; every MX output schema-valid, each transform listing what the mapping drops.
Verdicts
- A casebook of nineteen protocol-agnostic controls: structural and field validity (ISO 4217 currencies and decimals, BIC, IBAN, Luhn and ABA routing-number check digits, PIN-block, MAC and chip-data formats), card security verified under seeded keys, funds, currency, value date, duplicates, account and card state, transaction limits, mandates, references to originals, cancellation state, status and account reports, FIX session rules, market hours, listed instruments, positions and the prescribed reason code.
- Grounded argumentation semantics: every verdict is a graph you can read and a cited chain of steps.
- A second engine: the same controls written in quorum's casebook language and compiled by its
cbccompiler, which checks all 67,108,864 combinations of its 26 readings before emitting anything. Even the card cryptography is written twice. The two engines agree on all 120,204 generated test cases and on every shipped scenario. - A certificate for every verdict from the C++
prova-proofcompanion (SAT-backed with CaDiCaL), or the in-process checker. - Indeterminate is an answer, with the evidence that would settle it.
Testing
- 1,745 scenarios (1,542 ISO 20022, 126 ISO 8583, 77 FIX) and 32 suites, including a valid and a broken instance of every message in the ISO 20022 catalogue, each scenario run against a compliant and a defective target on every build. Generated families cover twenty countries' IBANs, every currency exponent, card numbers of 13 to 19 digits, every PIN block format, MAC and cryptogram version on each dialect, and the FIX controls and session rules on each FIX version.
- Twelve simulated targets: a reference payment host and a defective one, a SEPA host and a FedNow participant that screen every message against the scheme's rules, a generic, a Visa-style and a Mastercard-style card switch and a defective one, and FIX 4.2, 4.4 and 5.0 SP2 venues and a defective one.
- Certification-style packs: CBPR+, SEPA, FedNow, a Visa-style and a Mastercard-style card pack. They are prova's own; the schemes' certification cases are the schemes'.
- Scenarios in JavaScript or Lua, sandboxed, with standards-valid synthetic data (Luhn PANs, IBANs, BICs) and reproducible seeds.
- Load tests by count or duration, at a set rate, over persistent connections (one FIX session per worker), with throughput, p50/p95/p99 and a per-second timeline — every request still judged.
- Replay of production traffic:
prova importreads FIX logs, ISO 8583 dumps and ISO 20022 files, masks card numbers, IBANs, accounts and names, andprova run --replay-livesends it to a target at its recorded pace or any rate. - Record and replay: capture traffic as a cassette, re-prove it offline after the rules change.
- CI:
prova runwrites JUnit and JSON and fails the build on a failed proof;prova validategates on malformed messages.
Operation
- An embedded SQLite database of every run with its full proof, suite and load history, and an activity log — no database server.
- Reports: pass rate by day, target, protocol, scenario and person; suite and load history; engine disagreements; CSV export of every verdict.
- Sign-in with local accounts, OpenID Connect (Entra ID, Okta, Google, Keycloak) or SAML 2.0; roles viewer, operator, admin; sessions that survive a restart.
- HTTPS only, HSTS, same-origin writes, PBKDF2 password hashes, session tokens never stored.
- The reference manual is served by the binary at
/manual, with reference chapters generated from the code itself.
 The proof. A host accepted €150.00 against €142.00. The graph, the certificate and the second engine all say why that fails. |
 The dashboard. Verdicts, latency and the most recent runs, each one a click from its proof. |
 Reports. Every verdict from the database, by day, target, protocol, scenario and person, with CSV export. |
 Suites. Twenty-seven packs, load tests with a per-second timeline, and replay of captured traffic. |
 Validate. The official schema, then CBPR+, SEPA, SEPA Instant or FedNow, then your own usage-guideline schema. |
 Card security. PIN blocks, MACs and chip cryptograms with the published test keys, and the HSM check. |
 Transform. Eight MT ↔ MX pairs, each MX output valid against the official schema. |
 Counterparty. Act as the far side of the exchange and see the exact reply on the wire. |
 Sign-in. Local accounts, OpenID Connect and SAML; here, the public demonstration's account. |
 The manual. Served by the binary, numbered, printable to PDF, with reference chapters generated from the code. |
./prova
That serves https://localhost:8443. The first start prints the admin password once, and runs twenty scenarios at
the built-in simulators so every screen has real verdicts on it. Then:
prova user add alice operator # a colleague; prints her password once
prova -tls-cert cert.pem -tls-key key.pem # a real certificate for a shared server
prova -public-url https://prova.example.com:8443 \
-oidc-issuer https://login.microsoftonline.com/TENANT/v2.0 -oidc-client-id ID \
-oidc-client-secret-file /etc/prova/oidc-secret # single sign-on (or -saml-idp-metadata URL)
In CI:
prova run --suite regression-iso20022 --junit results.xml
prova run --scenario fix-over-limit --target fix-venue-bug # exits 1: defect caught
prova run --suite controls-iso20022 --record cassette.jsonl
prova run --replay cassette.jsonl # re-prove offline
prova validate --profile SEPA --sarif payment.xml # schema + SEPA rules, as SARIF
prova import --protocol iso8583 --dialect visa --mask --out auth.jsonl dump.hex
prova run --replay-live auth.jsonl --target visa-switch --speed 1 # production traffic, at its own pace
prova hsm --addr 10.0.0.5:1500 diagnostics # check a payShield-compatible HSM
Everything else — every option, every API endpoint, every shipped scenario and suite — is in the
manual, which every running prova also serves at /manual.
A public demonstration runs at https://prova.perfuse.health:9443 against prova's simulated targets only: sign in as
demo with try-prova-now (a viewer: it can look at everything and change nothing). A shipped scenario runs every
fifteen minutes, so the dashboard and reports stay current. Open a failed run and read its proof; compare the
second engine's verdict; download the CSV. How it is run is in deploy/demo/.
The established tools — jPOS and its client simulator, Paragon FASTest, Greenline VeriFIX, FIXSIM, X9Ware, Trace Financial, AskISO — between them cover thirteen kinds of capability. prova has something in each, and adds the one none of them has: a verdict that is a machine-checked proof. Breadth is a different matter, and is stated plainly here.
| Capability | prova today | Where the established tools go further |
|---|---|---|
| Simulated counterparties | twelve: payment hosts (reference, SEPA, FedNow), card switches (generic, Visa-style, Mastercard-style), FIX 4.2/4.4/5.0 venues, and a defective one per protocol | the schemes' own test hosts and the exact dialects of private networks |
| Message coverage | 15 ISO 20022 messages, 4 ISO 8583 MTIs in three dialects, FIX 4.2, 4.4 and 5.0 SP2 with 5 request types | hundreds of MX messages; more ISO 8583 networks (Discover, JCB, UnionPay, domestic schemes); hundreds of FIX message types |
| Field validation | ISO 4217, decimals, BIC, IBAN, Luhn, ABA routing numbers | — |
| Schema & profile validation | all 2,641 ISO 20022 schemas (libxml2-checked), CBPR+, SEPA, SEPA Inst and FedNow rules, a usage-guideline library (TCH RTP bundled, imports of MyStandards and EPC ZIPs), SARIF | every MyStandards guideline published, maintained by the vendor |
| Scenario library | 1,745 scenarios, 32 suites | libraries of thousands of cases |
| Certification packs | prova's own CBPR+, SEPA, FedNow, Visa-style and Mastercard-style packs | the schemes' official certification test cases |
| Card security | PIN blocks 0/1/3/4, ISO 9797-1 MACs, AES-CMAC, Visa CVN 10/18 and Mastercard CVN 16 cryptograms, PVV, CVV, verified by both engines; payShield HSM client | full EMV kernels (terminal risk management, CDA, offline data authentication); more HSM command sets |
| Load testing | count or duration, set rate, persistent sessions, per-second timeline, replay of imported production traffic with masking | distributed load generation across many machines |
| Negative testing | controls that prove a rejection was right, with the right reason | |
| CI/CD | prova run, JUnit and JSON, non-zero exit on failure |
|
| Synthetic data | Luhn PANs, IBANs, BICs, amounts, ids; seeded and reproducible | |
| Auditable evidence | every verdict a cited proof with a certificate, stored and exportable; findings as SARIF | |
| MT ↔ MX | eight pairs: MT103, MT202, MT103 RETN, MT192, MT196, MT900, MT910, MT940 | the full MT catalogue and the CBPR+ translation rules in every detail |
| FIX session testing | the session rules (sequence, possible duplicates, comp ids, garbled messages, gap fill) on FIX 4.2, 4.4 and 5.0 SP2 | FIX 4.0/4.1, FIXP and binary encodings (SBE) |
| Capture and replay | JSONL cassettes re-proved offline; FIX logs, ISO 8583 dumps and ISO 20022 files replayed live |
The right-hand column is drawn from the vendors' public material and is the roadmap; see docs/comparison.md.
HTTPS only (TLS 1.2+, HSTS). Every API call needs a session; anything that runs, stores or sends needs the operator role, and every POST must be JSON from prova's own origin. Passwords are generated, shown once and stored as PBKDF2-SHA256 hashes; session tokens are never stored, only their hashes; the database is readable by its owner only. Scenario scripts run sandboxed with no file, network or process access. prova sends nothing anywhere but to the targets you point it at and your identity provider. The Security chapter of the manual has the detail.
Report a vulnerability privately through this repository's Security tab ("Report a vulnerability"), not in a public issue.
Go 1.26 or newer; Node 20 and pnpm only to rebuild the interface, which is committed prebuilt.
make build # bin/prova
make test # go test ./...
make web # rebuild the interface into internal/web/dist
make proof # the C++ prova-proof companion (with CaDiCaL if ~/cadical is built)
make manual # docs/manual/prova-manual.html and .pdf
make release # per-platform archives in dist/release
The layout is described in docs/architecture.md.
Is the verdict produced by an AI model?
No. Verdicts come from explicit rules applied to the evidence under grounded argumentation semantics. The same exchange always gives the same verdict, and the proof shows which rule and which evidence decided it.
What does "indeterminate" mean?
That the evidence does not decide it — for example, a host accepted a payment over the balance and the scenario says an overdraft might cover it. prova names the evidence that would settle it rather than guessing.
Do I need the C++ companion?
No. Without prova-proof, prova performs the same checks in-process and says so on every certificate. With it, the
re-check is done by a separate program with a SAT solver, which is the stronger statement to give an auditor.
Can it test my real host?
Yes: point a scenario or a suite at your target's address. The simulated targets exist so that prova is useful the moment it starts and so you can see it catch a defect you know is there.
Where is my data kept?
In one SQLite file, prova.db, in the data directory (-data). Back it up by copying it while prova is stopped.
prova is developed and maintained by BioDream LLC. Pull requests will not be reviewed or merged. A verdict is only worth what its rules are worth, and keeping every rule proved, tested on every combination and cited is a discipline easier to keep in one place.
Bug reports are wanted. Open an issue with the output of
prova -version and, where a message is involved, a synthetic one. Never post real card numbers, account numbers or
customer data.
PolyForm Small Business License 1.0.0. Copyright 2026 BioDream LLC. See NOTICE.
A company with fewer than 100 people and less than USD 1 million in annual revenue may use prova freely. Larger companies need a commercial licence from BioDream LLC.
prova includes code from Perfuse, a separate BioDream project under the Apache License 2.0, whose licence and notice are in licenses/. ISO 20022, ISO 8583, FIX and SWIFT are named only to say what prova reads and writes; prova is not affiliated with or endorsed by ISO, the FIX Trading Community, SWIFT or any vendor named here.
Keywords
Payments: ISO 20022 testing · pacs.008 · pacs.009 · pacs.003 · pacs.010 · pacs.004 · camt.056 · camt.029 · pacs.028 · pain.001 · pacs.002 · camt.053 · camt.054 · camt.060 · XSD validation · CBPR+ · SEPA · SEPA Instant · FedNow · MyStandards · SARIF · IBAN validation · SWIFT MX · MT103 to pacs.008 · MT to MX migration · payment host testing · payment simulator · reason codes AM04 AM05 DT01
Cards: ISO 8583 testing · Visa BASE I · Mastercard · EBCDIC · card switch simulator · PIN block · ISO 9564 · MAC · ISO 9797 · ARQC · EMV cryptogram · CVN 10 · CVN 18 · payShield HSM · PVV · CVV · issuer host testing
Trading: FIX protocol testing · FIX 4.2 · FIX 4.4 · FIX 5.0 SP2 · FIX session testing · PossDupFlag · order mass cancel · FIX simulator · NewOrderSingle · OrderCancelRequest · OrderCancelReplaceRequest · ExecutionReport · OMS EMS testing
Proof: formal verification · argumentation · grounded semantics · SAT solver · CaDiCaL · explainable verdicts · audit evidence · PCI DSS · SOX · regression testing · load testing · single binary · Go · OpenID Connect · SAML