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Fix isValidSignature method #171

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Feb 4, 2019
Merged

Fix isValidSignature method #171

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5d316ce
Fix jsdoc param type of v for documentation of isValidSignature
danjm Jan 4, 2019
7fb0a30
Fix validation of s size in isValidSignature so that it applies to th…
danjm Jan 4, 2019
777241f
Improve readibility and defaults of homestead or greater checks in is…
danjm Feb 1, 2019
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4 changes: 2 additions & 2 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -571,7 +571,7 @@ exports.addHexPrefix = function (str) {
/**
* Validate ECDSA signature
* @method isValidSignature
* @param {Buffer} v
* @param {Number} v
* @param {Buffer} r
* @param {Buffer} s
* @param {Boolean} [homestead=true]
Expand All @@ -598,7 +598,7 @@ exports.isValidSignature = function (v, r, s, homestead, chainId) {
return false
}

if ((homestead === false) && (new BN(s).cmp(SECP256K1_N_DIV_2) === 1)) {
if (homestead && (new BN(s).cmp(SECP256K1_N_DIV_2) === 1)) {
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return false
}

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18 changes: 18 additions & 0 deletions test/index.js
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Expand Up @@ -558,6 +558,24 @@ describe('isValidSignature', function () {
const s = Buffer.from('129ff05af364204442bdb53ab6f18a99ab48acc9326fa689f228040429e3ca66', 'hex')
assert.equal(ethUtils.isValidSignature(29, r, s), false)
})
it('should fail when on homestead and s > secp256k1n/2', function () {
const SECP256K1_N_DIV_2 = new BN('7fffffffffffffffffffffffffffffff5d576e7357a4501ddfe92f46681b20a0', 16)

const r = Buffer.from('99e71a99cb2270b8cac5254f9e99b6210c6c10224a1579cf389ef88b20a1abe9', 'hex')
const s = Buffer.from(SECP256K1_N_DIV_2.add(new BN('1', 16)).toString(16), 'hex')

const v = 27
assert.equal(ethUtils.isValidSignature(v, r, s), true)
})
it('should not fail when not on homestead but s > secp256k1n/2', function () {
const SECP256K1_N_DIV_2 = new BN('7fffffffffffffffffffffffffffffff5d576e7357a4501ddfe92f46681b20a0', 16)

const r = Buffer.from('99e71a99cb2270b8cac5254f9e99b6210c6c10224a1579cf389ef88b20a1abe9', 'hex')
const s = Buffer.from(SECP256K1_N_DIV_2.add(new BN('1', 16)).toString(16), 'hex')

const v = 27
assert.equal(ethUtils.isValidSignature(v, r, s), true)
})
it('should work otherwise', function () {
const r = Buffer.from('99e71a99cb2270b8cac5254f9e99b6210c6c10224a1579cf389ef88b20a1abe9', 'hex')
const s = Buffer.from('129ff05af364204442bdb53ab6f18a99ab48acc9326fa689f228040429e3ca66', 'hex')
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