Opcodes used in Script
This is a list of all Script words, also known as opcodes, commands, or functions.
OP_NOP1-OP_NOP10 were originally set aside to be used when HASH and other security functions become insecure due to improvements in computing.
False is zero or negative zero (using any number of bytes) or an empty array, and True is anything else.
Opcodes that will be activated in the Chronicle Release are indicated by an asterisk (e.g. OP_VER*).
Constants
When talking about scripts, these value-pushing words are usually omitted.
| Word | Opcode | Input | Output | Description |
|---|---|---|---|---|
OP_0, OP_FALSE | 0 0x00 | Nothing. | (empty value) | An empty array of bytes is pushed onto the stack. (This is not a no-op: an item is added to the stack.) |
Pushdata Bytelength | 1-75 0x01-0x4b | (special) | data | The next opcode bytes is data to be pushed onto the stack |
OP_PUSHDATA1 | 76 0x4c | (special) | data | The next byte contains the number of bytes to be pushed onto the stack. |
OP_PUSHDATA2 | 77 0x4d | (special) | data | The next two bytes contain the number of bytes to be pushed onto the stack in little endian order. |
OP_PUSHDATA4 | 78 0x4e | (special) | data | The next four bytes contain the number of bytes to be pushed onto the stack in little endian order. |
OP_1NEGATE | 79 0x4f | Nothing. | -1 | The number -1 is pushed onto the stack. |
OP_1, OP_TRUE | 81 0x51 | Nothing. | 1 | The number 1 is pushed onto the stack. |
OP_2-OP_16 | 82-96 0x52-0x60 | Nothing. | 2-16 | The number in the word name (2-16) is pushed onto the stack. |
Flow control
| Word | Opcode | Input | Output | Description |
|---|---|---|---|---|
OP_NOP | 97 0x61 | Nothing | Nothing | Does nothing. |
OP_VER* | 98 0x62 | Nothing | Transaction version | Puts the transaction version onto the stack. |
OP_IF | 99 0x63 |
| If the top stack value is TRUE, statement 1 is executed. If the top stack value is FALSE and ELSE is used, statement 2 is executed. If ELSE is NOT used, the script jumps to ENDIF. The top stack value is removed. | |
OP_NOTIF | 100 0x64 |
ELSE
| If the top stack value is FALSE, statement 1 is executed. If the top stack value is TRUE and ELSE is used, statement 2 is executed. If ELSE is NOT used, the script jumps to ENDIF. The top stack value is removed. | |
OP_VERIF* | 101 0x65 | x1 = 4-byte array | Result of conditionally executed statement | Same semantics as: x1 transaction_version |
OP_VERNOTIF* | 102 0x66 | x1 = 4-byte array | Result of conditionally executed statement | Same semantics as: x1 transaction_version |
OP_ELSE | 103 0x67 |
ELSE
| If the preceding IF or NOTIF check was not valid then statement 2 is executed. | |
OP_ENDIF | 104 0x68 |
| Ends an if/else block. All blocks must end, or the transaction is invalid. An OP_ENDIF without a prior matching OP_IF or OP_NOTIF is also invalid. | |
OP_VERIFY | 105 0x69 | True / false | Nothing / fail | Marks transaction as invalid if top stack value is not true. The top stack value is removed. |
OP_RETURN | 106 0x6a | Nothing | Ends script with top value on stack as final result | OP_RETURN can also be used to create "False Return" outputs with a scriptPubKey consisting of OP_FALSE OP_RETURN followed by data. Such outputs are provably unspendable and should be given a value of zero Satoshis. These outputs can be pruned from storage in the UTXO set, reducing its size. Currently the BitcoinSV network supports multiple FALSE RETURN outputs in a given transaction with each one capable of holding up to 100kB of data. After the Genesis upgrade in 2020 miners will be free to mine transactions containing FALSE RETURN outputs of any size. |
Stack
| Word | Opcode | Input | Output | Description |
|---|---|---|---|---|
OP_TOALTSTACK | 107 0x6b | x1 | (alt)x1 | Puts the input onto the top of the alt stack. Removes it from the main stack. |
OP_FROMALTSTACK | 108 0x6c | (alt)x1 | x1 | Puts the input onto the top of the main stack. Removes it from the alt stack. |
OP_2DROP | 109 0x6d | x1 x2 | Nothing | Removes the top two stack items. |
OP_2DUP | 110 0x6e | x1 x2 | x1 x2 x1 x2 | Duplicates the top two stack items. |
OP_3DUP | 111 0x6f | x1 x2 x3 | x1 x2 x3 x1 x2 x3 | Duplicates the top three stack items. |
OP_2OVER | 112 0x70 | x1 x2 x3 x4 | x1 x2 x3 x4 x1 x2 | Copies the pair of items two spaces back in the stack to the front. |
OP_2ROT | 113 0x71 | x1 x2 x3 x4 x5 x6 | x3 x4 x5 x6 x1 x2 | The fifth and sixth items back are moved to the top of the stack. |
OP_2SWAP | 114 0x72 | x1 x2 x3 x4 | x3 x4 x1 x2 | Swaps the top two pairs of items. |
OP_IFDUP | 115 0x73 | x | x / x x | If the top stack value is not 0, duplicate it. |
OP_DEPTH | 116 0x74 | Nothing | <Stack size> | Counts the number of stack items onto the stack and places the value on the top |
OP_DROP | 117 0x75 | x | Nothing | Removes the top stack item. |
OP_DUP | 118 0x76 | x | x x | Duplicates the top stack item. |
OP_NIP | 119 0x77 | x1 x2 | x2 | Removes the second-to-top stack item. |
OP_OVER | 120 0x78 | x1 x2 | x1 x2 x1 | Copies the second-to-top stack item to the top. |
OP_PICK | 121 0x79 | xn ... x2 x1 x0 <n> | xn ... x2 x1 x0 xn | The item n back in the stack is copied to the top. |
OP_ROLL | 122 0x7a | xn ... x2 x1 x0 <n> | ... x2 x1 x0 xn | The item n back in the stack is moved to the top. |
OP_ROT | 123 0x7b | x1 x2 x3 | x2 x3 x1 | The top three items on the stack are rotated to the left. |
OP_SWAP | 124 0x7c | x1 x2 | x2 x1 | The top two items on the stack are swapped. |
OP_TUCK | 125 0x7d | x1 x2 | x2 x1 x2 | The item at the top of the stack is copied and inserted before the second-to-top item. |
Data Manipulation
| Word | Opcode | Input | Output | Description |
|---|---|---|---|---|
OP_CAT | 126 0x7e | x1 x2 | out | Concatenates two strings. |
OP_SPLIT | 127 0x7f | x n | x1 x2 | Splits byte sequence x at position n. |
OP_NUM2BIN | 128 0x80 | a b | out | Converts numeric value a into byte sequence of length b. |
OP_BIN2NUM | 129 0x81 | x | out | Converts byte sequence x into a numeric value. |
OP_SIZE | 130 0x82 | in | in size | Pushes the string length of the top element of the stack (without popping it). |
Bitwise logic
| Word | Opcode | Input | Output | Description |
|---|---|---|---|---|
OP_INVERT | 131 0x83 | in | out | Flips all of the bits in the input. |
OP_AND | 132 0x84 | x1 x2 | out | Boolean and between each bit in the inputs. |
OP_OR | 133 0x85 | x1 x2 | out | Boolean or between each bit in the inputs. |
OP_XOR | 134 0x86 | x1 x2 | out | Boolean exclusive or between each bit in the inputs. |
OP_EQUAL | 135 0x87 | x1 x2 | True / false | Returns 1 if the inputs are exactly equal, 0 otherwise. |
OP_EQUALVERIFY | 136 0x88 | x1 x2 | Nothing / fail | Same as OP_EQUAL, but runs OP_VERIFY afterward. |
Arithmetic
BitcoinScript supports arithmetic on bignum values A bignum is a byte sequence that represents a numeric value. The length of the byte sequence must be less than or equal to 750,000 bytes. Byte sequences larger than 750,000 bytes are valid in Bitcoin however current rules dictate that they are not recognised as a valid numeric value.
Note that while some operations require parameters to be valid numeric values, they may produce byte sequences which are not valid numeric values (for example, OP_MUL may produce a byte sequence which is too large to validly represent a numeric value).
| Word | Opcode | Input | Output | Description |
|---|---|---|---|---|
OP_1ADD | 139 0x8b | in | out | 1 is added to the input. |
OP_1SUB | 140 0x8c | in | out | 1 is subtracted from the input. |
OP_2MUL* | 141 0x8d | in | out | The input is multiplied by 2. |
OP_2DIV* | 142 0x8e | in | out | The input is divided by 2. |
OP_NEGATE | 143 0x8f | in | out | The sign of the input is flipped. |
OP_ABS | 144 0x90 | in | out | The input is made positive. |
OP_NOT | 145 0x91 | in | out | If the input is 0 or 1, it is flipped. Otherwise the output will be 0. |
OP_0NOTEQUAL | 146 0x92 | in | out | Returns 0 if the input is 0. 1 otherwise. |
OP_ADD | 147 0x93 | a b | out | a is added to b. |
OP_SUB | 148 0x94 | a b | out | b is subtracted from a. |
OP_MUL | 149 0x95 | a b | out | a is multiplied by b. |
OP_DIV | 150 0x96 | a b | out | a is divided by b. |
OP_MOD | 151 0x97 | a b | out | Returns the remainder after dividing a by b. |
OP_LSHIFT | 152 0x98 | a b | out | Logical left shift b bits. Sign data is discarded |
OP_RSHIFT | 153 0x99 | a b | out | Logical right shift b bits. Sign data is discarded |
OP_BOOLAND | 154 0x9a | a b | out | If both a and b are not 0, the output is 1. Otherwise 0. |
OP_BOOLOR | 155 0x9b | a b | out | If a or b is not 0, the output is 1. Otherwise 0. |
OP_NUMEQUAL | 156 0x9c | a b | out | Returns 1 if the numbers are equal, 0 otherwise. |
OP_NUMEQUALVERIFY | 157 0x9d | a b | Nothing / fail | Same as OP_NUMEQUAL, but runs OP_VERIFY afterward. |
OP_NUMNOTEQUAL | 158 0x9e | a b | out | Returns 1 if the numbers are not equal, 0 otherwise. |
OP_LESSTHAN | 159 0x9f | a b | out | Returns 1 if a is less than b, 0 otherwise. |
OP_GREATERTHAN | 160 0xa0 | a b | out | Returns 1 if a is greater than b, 0 otherwise. |
OP_LESSTHANOREQUAL | 161 0xa1 | a b | out | Returns 1 if a is less than or equal to b, 0 otherwise. |
OP_GREATERTHANOREQUAL | 162 0xa2 | a b | out | Returns 1 if a is greater than or equal to b, 0 otherwise. |
OP_MIN | 163 0xa3 | a b | out | Returns the smaller of a and b. |
OP_MAX | 164 0xa4 | a b | out | Returns the larger of a and b. |
OP_WITHIN | 165 0xa5 | x min max | out | Returns 1 if x is within the specified range (left-inclusive), 0 otherwise. |
Cryptography
| Word | Opcode | Input | Output | Description |
|---|---|---|---|---|
OP_RIPEMD160 | 166 0xa6 | in | hash | The input is hashed using RIPEMD-160. |
OP_SHA1 | 167 0xa7 | in | hash | The input is hashed using SHA-1. |
OP_SHA256 | 168 0xa8 | in | hash | The input is hashed using SHA-256. |
OP_HASH160 | 169 0xa9 | in | hash | The input is hashed twice: first with SHA-256 and then with RIPEMD-160. |
OP_HASH256 | 170 0xaa | in | hash | The input is hashed two times with SHA-256. |
OP_CODESEPARATOR | 171 0xab | Nothing | Nothing | All of the signature checking words will only match signatures to the data after the most recently-executed OP_CODESEPARATOR. |
OP_CHECKSIG | 172 0xac | sig pubkey | True / false | The entire transaction's outputs, inputs, and script (from the most recently-executed OP_CODESEPARATOR to the end) are hashed. The signature used by OP_CHECKSIG must be a valid signature for this hash and public key. If it is, 1 is returned, 0 otherwise. |
OP_CHECKSIGVERIFY | 173 0xad | sig pubkey | Nothing / fail | Same as OP_CHECKSIG, but OP_VERIFY is executed afterward. |
OP_CHECKMULTISIG | 174 0xae | x sig1 sig2 ... <number of signatures> pub1 pub2 <number of public keys> | True / False | Compares the first signature against each public key until it finds an ECDSA match. Starting with the subsequent public key, it compares the second signature against each remaining public key until it finds an ECDSA match. The process is repeated until all signatures have been checked or not enough public keys remain to produce a successful result. All signatures need to match a public key. Because public keys are not checked again if they fail any signature comparison, signatures must be placed in the scriptSig using the same order as their corresponding public keys were placed in the scriptPubKey or redeemScript. If all signatures are valid, 1 is returned, 0 otherwise. Due to a bug, an extra unused value (x) is removed from the stack. Script spenders must account for this by adding a junk value (typically zero) to the stack. |
OP_CHECKMULTISIGVERIFY | 175 0xaf | x sig1 sig2 ... <number of signatures> pub1 pub2 ... <number of public keys> | Nothing / fail | Same as OP_CHECKMULTISIG, but OP_VERIFY is executed afterward. |
Used NOP opcode identifiers
In Bitcoin's history, new opcodes were added that used reserved NO_OP opcode identifiers. These opcodes have been reverted to the original OP_NOP functionality.
| Word | Opcode | Input | Output | Description |
|---|---|---|---|---|
OP_NOP2 (previously OP_CHECKLOCKTIMEVERIFY) | 177 0xb1 | Nothing (Previously: x) | Nothing (Previously: x or fail) | NO OPERATION Evaluation process for UTXOs that pre-date genesis: Mark transaction as invalid if the top stack item is greater than the transaction's nLockTime field, otherwise script evaluation continues as though an OP_NOP was executed. Transaction is also invalid if 1. the stack is empty; or 2. the top stack item is negative; or 3. the top stack item is greater than or equal to 500000000 while the transaction's nLockTime field is less than 500000000, or vice versa; or 4. the input's nSequence field is equal to 0xffffffff. The precise semantics are described in BIP 0065. |
OP_NOP3 (previously OP_CHECKSEQUENCEVERIFY) | 178 0xb2 | Nothing (Previously: x) | Nothing (Previously: x or fail) |
String operations
| Word | Opcode | Input | Output | Description |
|---|---|---|---|---|
OP_SUBSTR* | 179 0xb3 | x1 x2 x3 | output string | The substring created from the string (x3) starting at the specified index (x2) and of the specified length (x1). |
OP_LEFT* | 180 0xb4 | x1 x2 | output string | The substring created from the string (x2) starting at the begining of the string and of the specified length (x1). |
OP_RIGHT* | 181 0xb5 | x1 x2 | output string | The substring created from the string (x2) using the specified number (x1) of rightmost characters. |
Pseudo-words
These words are used internally for assisting with transaction matching. They are invalid if used in actual scripts.
| Word | Opcode | Description |
|---|---|---|
OP_PUBKEYHASH | 253 0xfd | Represents a public key hashed with OP_HASH160. |
OP_PUBKEY | 254 0xfe | Represents a public key compatible with OP_CHECKSIG. |
OP_INVALIDOPCODE | 255 0xff | Matches any opcode that is not yet assigned. |
Reserved words
Any opcode not assigned is also reserved. Using an unassigned opcode makes the transaction invalid.
| Word | Opcode | When used... |
|---|---|---|
OP_RESERVED | 80 0x50 | Transaction is invalid unless occuring in an unexecuted OP_IF branch |
OP_RESERVED1 | 137 0x89 | Transaction is invalid unless occuring in an unexecuted OP_IF branch |
OP_RESERVED2 | 138 0x8a | Transaction is invalid unless occuring in an unexecuted OP_IF branch |
OP_NOP1, OP_NOP4-OP_NOP10 | 176, 179-185 0xb0, 0xb3-0xb9 | The word is ignored. Does not mark transaction as invalid. |
Examples
For examples of common Bitcoin transaction scripts please see Bitcoin Transactions
Attribution
This content is based on content sourced from https://en.bitcoin.it/wiki/Script under Creative Commons Attribution 3.0. Although it may have been extensively revised and updated we acknowledge the original authors.
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