Opcodes¶

Script opcode reference. Navio inherits Bitcoin's Script language and adds BLSCT-specific opcodes.

Navio-specific¶

`OP_BLSCHECKSIG` — `0xb3` (formerly `OP_NOP4`)¶

Stack: (pubkey -- bool)

Verifies a BLS12-381 signature against a public key. Replaces OP_CHECKSIG in BLSCT-aware scripts (atomic swaps, custom HTLC flows).

<pubkey> OP_BLSCHECKSIG

Field	Requirement
Public key	48 bytes, compressed \(G_1\) point
Signature	48 bytes, compressed \(G_1\) signature
Return value	`1` (true) on valid signature, `0` otherwise

The signature is pulled from the scriptSig / witness of the spending input; the opcode itself consumes the public key from the stack and pushes a boolean.

Usage pattern in an HTLC:

OP_IF
    OP_HASH160 <hash_A> OP_EQUALVERIFY
    <counterparty_bls_pubkey> OP_BLSCHECKSIG
OP_ELSE
    <timelock> OP_CHECKLOCKTIMEVERIFY OP_DROP
    <self_bls_pubkey> OP_BLSCHECKSIG
OP_ENDIF

See atomic swaps for the full context.

Opcode byte value

The source of truth is src/script/script.h in navio-core. Historical Navcoin documentation and some third-party references list OP_BLSCHECKSIG as 0xbb; the current consensus value is 0xb3 (reusing the former OP_NOP4). Always verify against the source for the release you target.

Inherited from Bitcoin Script¶

Standard Bitcoin Script opcodes are supported. The complete table is maintained in src/script/script.h. Common ones:

Constants¶

Opcode	Hex	Effect
`OP_0`	0x00	Push 0 (empty string)
`OP_1NEGATE`	0x4f	Push -1
`OP_1`…`OP_16`	0x51–0x60	Push 1–16
`OP_PUSHDATA1/2/4`	0x4c-0x4e	Push next N bytes

Flow control¶

Opcode	Hex	Effect
`OP_IF`	0x63	Conditional begin
`OP_NOTIF`	0x64	Inverted conditional
`OP_ELSE`	0x67	Else branch
`OP_ENDIF`	0x68	End conditional
`OP_VERIFY`	0x69	Fail if top of stack is false
`OP_RETURN`	0x6a	Mark output as provably unspendable (burn)

Stack¶

Opcode	Hex
`OP_DUP`	0x76
`OP_DROP`	0x75
`OP_SWAP`	0x7c
`OP_2DUP`	0x6e
`OP_TOALTSTACK`	0x6b
`OP_FROMALTSTACK`	0x6c

Bitwise / arithmetic¶

Opcode	Hex
`OP_EQUAL`	0x87
`OP_EQUALVERIFY`	0x88
`OP_ADD`	0x93
`OP_SUB`	0x94
`OP_BOOLAND`	0x9a
`OP_NUMEQUAL`	0x9c

Cryptographic¶

Opcode	Hex	Notes
`OP_RIPEMD160`	0xa6
`OP_SHA1`	0xa7
`OP_SHA256`	0xa8
`OP_HASH160`	0xa9	SHA256 then RIPEMD160. Used in HTLCs.
`OP_HASH256`	0xaa	Double SHA256
`OP_CODESEPARATOR`	0xab	Rarely used
`OP_CHECKSIG`	0xac	Traditional ECDSA signature check
`OP_CHECKSIGVERIFY`	0xad
`OP_CHECKMULTISIG`	0xae	Legacy multisig
`OP_CHECKMULTISIGVERIFY`	0xaf
`OP_BLSCHECKSIG`	0xb3	Navio-specific — BLS signature check

Timelock¶

Opcode	Hex
`OP_CHECKLOCKTIMEVERIFY`	0xb1
`OP_CHECKSEQUENCEVERIFY`	0xb2

Unsupported / repurposed¶

Some OP_NOPx opcodes have been repurposed:

OP_NOP4 → OP_BLSCHECKSIG (0xb3).

Any other OP_NOPx remains a no-op and passes validation. Custom scripts using them as markers still work.