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ContextUtils

bitcoinjs-lib v0.2.9-beta.16

bitcoinjs-lib / ContextUtils

Class: ContextUtils

Defined in: packages/scrypt-ts-btc/src/smart-contract/builtin-libs/contextUtils.ts:15

Library for verifying preimage.

Onchain​

Extends​

Constructors​

new ContextUtils()​

new ContextUtils(...args): ContextUtils

Defined in: packages/scrypt-ts-btc/src/smart-contract/smartContractLib.ts:29

Parameters​

args​

...SupportedParamType[]

Returns​

ContextUtils

Inherited from​

SmartContractLib.constructor

Properties​

args​

args: any[] = []

Defined in: packages/scrypt-ts-btc/src/smart-contract/smartContractLib.ts:28

Inherited from​

SmartContractLib.args

artifact​

static artifact: Artifact

Defined in: packages/scrypt-ts-btc/src/smart-contract/smartContractLib.ts:15

Inherited from​

SmartContractLib.artifact

ePreimagePrefix​

readonly static ePreimagePrefix: ByteString

Defined in: packages/scrypt-ts-btc/src/smart-contract/builtin-libs/contextUtils.ts:87

A fixed preimage prefix. https://github.com/bitcoin/bips/blob/master/bip-0340/reference.py#L114 e = taggedHash('BIP0340/challenge', bytes(R) || bytes(P) || m)

tagHash = sha256('BIP0340/challenge') = 7bb52d7a9fef58323eb1bf7a407db382d2f3f2d81bb1224f49fe518f6d48d37c

e = sha256(tagHash || tagHash || bytes(R) || bytes(P) || m)

we define: ePreimagePrefix = tagHash || tagHash || bytes(R) || bytes(P)

e = sha256(ePreimagePrefix || m)

default signing process Sign(sk, m) defines in BIP-340 https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki#default-signing

we use the private key sk = 1 to sign the message, so d' = 1 d' is good in range (0, n) P = d'G = G has_even_y(P) = has_even_y(G) = True d = d' if has_even_y(P) = 1 and we do not derive k' to generate the random point R but use G directly k' = 1 R = k'G = G has_even_y(R) = has_even_y(G) = True k = k' if has_even_y(R) = 1

ePreimagePrefix = tagHash || tagHash || Gx || Gx

Gx​

readonly static Gx: PubKey

Defined in: packages/scrypt-ts-btc/src/smart-contract/builtin-libs/contextUtils.ts:18

X coordinate of secp256k1 generator point

preimagePrefix​

readonly static preimagePrefix: ByteString

Defined in: packages/scrypt-ts-btc/src/smart-contract/builtin-libs/contextUtils.ts:51

A fixed preimage prefix. https://github.com/bitcoin/bips/blob/master/bip-0340/reference.py#L25 taggedHash(tag, m) = sha256(sha256(tag) || sha256(tag) || m)

https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki#common-signature-message BIP-341 defines Common Signature Message, SigMsg(hash_type, ext_flag)

https://github.com/bitcoin/bips/blob/master/bip-0342.mediawiki#common-signature-message-extension BIP-342 defines tapscript message extension (ext) to BIP-341 Common Signature Message, indicated by ext_flag = 1:

  • tapLeafHash
  • keyVersion
  • codeSepPos

hash type uses 0x00 (SIGHASH_DEFAULT), so the message m to checksig is

taggedHash('TapSighash', 0x00 || SigMsg(0x00, 1) || ext)
                          |              |    |
                   sighashEpoch     hashType  extFlag

tagHash = sha256('TapSighash') = f40a48df4b2a70c8b4924bf2654661ed3d95fd66a313eb87237597c628e4a031

=> sha256(tagHash || tagHash || 0x00 || SigMsg(0x00, 1) || ext)

we define: preimage = SigMsg(0x00, 1) || ext preimagePrefix = tagHash || tagHash || 0x00

stateType?​

static optional stateType: string

Defined in: packages/scrypt-ts-btc/src/smart-contract/smartContractLib.ts:16

Inherited from​

SmartContractLib.stateType

Methods​

checkPrevouts()​

static checkPrevouts(prevouts, prevout, t_shaPrevouts, t_inputIndexVal): Int32

Defined in: packages/scrypt-ts-btc/src/smart-contract/builtin-libs/contextUtils.ts:173

Verify that the prevouts context passed in by the user is authentic

Parameters​

prevouts​

Prevouts

prevouts context passed in by the user that need to be verified

prevout​

Outpoint

prevout context passed in by the user that need to be verified

t_shaPrevouts​

ByteString

shaPrevouts in preimage which is trustable

t_inputIndexVal​

Int32

the index of the input, which is trustable

Returns​

Int32

the number of inputs, which is trustable

checkSHPreimage()​

static checkSHPreimage(shPreimage): Sig

Defined in: packages/scrypt-ts-btc/src/smart-contract/builtin-libs/contextUtils.ts:97

sign the transaction preimage

Parameters​

shPreimage​

SHPreimage

the transaction preimage

Returns​

Sig

a signature

checkSpentAmounts()​

static checkSpentAmounts(spentAmounts, t_shaSpentAmounts, t_inputCount): void

Defined in: packages/scrypt-ts-btc/src/smart-contract/builtin-libs/contextUtils.ts:217

Check if the spent amounts array passed in matches the shaSpentAmounts

Parameters​

spentAmounts​

SpentAmounts

array of spent amounts passed in that need to be verified

t_shaSpentAmounts​

ByteString

the hash of the merged spent amounts, which comes from preimage and is trustable

t_inputCount​

bigint

must be trustable, the number of inputs

Returns​

void

checkSpentScripts()​

static checkSpentScripts(spentScripts, t_shaSpentScripts, t_inputCount): void

Defined in: packages/scrypt-ts-btc/src/smart-contract/builtin-libs/contextUtils.ts:199

Check if the spent scripts array passed in matches the shaSpentScripts

Parameters​

spentScripts​

SpentScripts

array of spent scripts passed in that need to be verified

t_shaSpentScripts​

ByteString

the hash of the merged spent scripts, which comes from preimage and is trustable

t_inputCount​

bigint

must be trustable, the number of inputs

Returns​

void

loadArtifact()​

static loadArtifact(artifact): typeof SmartContractLib

Defined in: packages/scrypt-ts-btc/src/smart-contract/smartContractLib.ts:18

Parameters​

artifact​

Artifact

Returns​

typeof SmartContractLib

Inherited from​

SmartContractLib.loadArtifact