Miniscript Lifter

A command-line tool for analyzing Bitcoin scripts and determining their liftability to Miniscript, plus a derived Policy.

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What it does

lift accepts a Bitcoin script hex and reports whether it can be lifted to Miniscript.
If liftable, it prints:

• Miniscript (script-level form, e.g., pk_k(...), and_v(...), older(...))
• Policy (high-level form, e.g., pk(...), thresh(...), or(...))

This is useful for:

• Understanding spending conditions
• Converting complex scripts into human-readable policies
• Checking whether a script is safely inside Miniscript’s analyzable subset

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Installation

cargo build --release

The binary will be at:

target/release/lift

Ensure your crate/bin is named lift so the path matches.

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Usage

1) Direct spending script

A “spending script” is the actual script that executes (e.g., a redeemScript for P2SH, witnessScript for P2WSH, or tapscript for Taproot).

./lift <script_hex>

2) scriptPubKey + spending script

When the first argument is a scriptPubKey, pass the committed spending script as the second argument:

./lift <scriptpubkey_hex> <spending_script_hex>

• P2WSH (BIP141): second arg is the witnessScript
  The tool verifies the witness program equals sha256(witnessScript).
• P2SH (BIP16): second arg is the redeemScript
  The tool verifies the redeem hash equals hash160(redeemScript).
• P2TR (Taproot, BIP341/342): second arg is the tapscript (tapleaf)
  Note: the tool only checks tapscript liftability; it does not verify the control block/path.
• P2WPKH: not supported here (no separate spending script exists to analyze).

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Examples

A) Direct spending script

This script encodes: pk1 CHECKSIGVERIFY; pk2 CHECKSIG, which lifts to and_v(v:pk_k(pk1), pk_k(pk2)):

./lift 2102f9308a019258c31049344f85f89d5229b531c845836f99b08601f113bce036f9ad2103a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bdac

Output:

LIFTABLE: SAFE
Miniscript: and_v(v:pk_k(02f9308a019258c31049344f85f89d5229b531c845836f99b08601f113bce036f9),pk_k(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))
Policy: and(pk(02f9308a019258c31049344f85f89d5229b531c845836f99b08601f113bce036f9),pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))

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B) P2WSH scriptPubKey + witnessScript (2-of-3 multisig)

• witnessScript (2-of-3 multisig):

  522102f9308a019258c31049344f85f89d5229b531c845836f99b08601f113bce036f9
  2103a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd
  2103defdea4cdb677750a420fee807eacf21eb9898ae79b9768766e4faa04a2d4a34
  53ae
  

• scriptPubKey (OP_0 <sha256(witnessScript)>):

  002060b665d87f99f11647a951457422794037e020d4d88da1421b5a8c31428067ba
  

Run:

./lift "002060b665d87f99f11647a951457422794037e020d4d88da1421b5a8c31428067ba" \
       "522102f9308a019258c31049344f85f89d5229b531c845836f99b08601f113bce036f9\
2103a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd\
2103defdea4cdb677750a420fee807eacf21eb9898ae79b9768766e4faa04a2d4a34\
53ae"

The tool verifies the SPK’s witness program equals sha256(witnessScript), then lifts the witnessScript (expect multi(2, ...) or thresh(2, ...)).

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Output & exit codes

The first line is always decisive:

• LIFTABLE: SAFE — analysis passed (exit 0)
• LIFTABLE: UNSAFE - <reason> — parsed but analysis failed (exit 1)
• NOT_LIFTABLE: <reason> — invalid/unsupported input or cannot be lifted (exit 3)

When liftable, the program also prints Miniscript and Policy.

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Supported inputs

• Direct spending scripts: redeemScript, witnessScript, tapscript
• P2WSH scriptPubKey + witnessScript (hash verified)
• P2SH scriptPubKey + redeemScript (hash verified)
• P2TR scriptPubKey + tapscript (liftability only; no control-block verification)

Not supported: P2WPKH scriptPubKeys (no separate spending script to analyze).

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Why scriptPubKeys can’t be lifted by themselves

A scriptPubKey only contains (or commits to) a hash/program of the actual spending script.
Without the corresponding redeemScript / witnessScript / tapscript, the tool cannot analyze spending conditions for liftability.

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Miniscript refresher

Miniscript is a structured language for expressing Bitcoin Script that enables:

• Automatic safety analysis (standardness, malleability, timelocks, etc.)
• Round-tripping between Script ⇄ Miniscript for the supported fragment set
• Derivation of a readable Policy form such as thresh(2, pk(A), pk(B), pk(C))

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Dependencies

• miniscript — Miniscript and re-exported bitcoin types
• hex — hex parsing