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ECSignature: verbose comments are overly verbose, see BIP if necessary

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Daniel Cousens 2015-07-07 18:04:52 +10:00
parent e42bd133fe
commit 5021714a85
1 changed files with 0 additions and 28 deletions
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src/ecsignature.js
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@ -36,53 +36,25 @@ ECSignature.parseCompact = function (buffer) {
// NOTE: SIGHASH byte ignored // NOTE: SIGHASH byte ignored
ECSignature.fromDER = function (buffer) { ECSignature.fromDER = function (buffer) {
// Format: 0x30 [total-length] 0x02 [R-length] [R] 0x02 [S-length] [S] // Format: 0x30 [total-length] 0x02 [R-length] [R] 0x02 [S-length] [S]
// Minimum and maximum size constraints.
if (buffer.length < 8) throw new Error('DER sequence too short') if (buffer.length < 8) throw new Error('DER sequence too short')
if (buffer.length > 72) throw new Error('DER sequence too long') if (buffer.length > 72) throw new Error('DER sequence too long')
// A signature is of type 0x30 (compound).
if (buffer[0] !== 0x30) throw new Error('Not a DER sequence') if (buffer[0] !== 0x30) throw new Error('Not a DER sequence')
// Make sure the length covers the entire signature.
if (buffer[1] !== buffer.length - 2) throw new Error('Invalid sequence length') if (buffer[1] !== buffer.length - 2) throw new Error('Invalid sequence length')
// Check whether the R element is an integer.
if (buffer[2] !== 0x02) throw new Error('Expected a DER integer') if (buffer[2] !== 0x02) throw new Error('Expected a DER integer')
// Extract the length of the R element.
var lenR = buffer.readUInt8(3) var lenR = buffer.readUInt8(3)
// Zero-length integers are not allowed for R.
if (lenR === 0) throw new Error('R length is zero') if (lenR === 0) throw new Error('R length is zero')
// Make sure the length of the R element is still inside the signature.
if (5 + lenR >= buffer.length) throw new Error('Invalid DER encoding') if (5 + lenR >= buffer.length) throw new Error('Invalid DER encoding')
// Check whether the S element is an integer.
if (buffer[4 + lenR] !== 0x02) throw new Error('Expected a DER integer (2)') if (buffer[4 + lenR] !== 0x02) throw new Error('Expected a DER integer (2)')
var lenS = buffer[5 + lenR] var lenS = buffer[5 + lenR]
// Zero-length integers are not allowed for S.
if (lenS === 0) throw new Error('S length is zero') if (lenS === 0) throw new Error('S length is zero')
// Verify that the length of the signature matches the sum of the length
// of the elements.
if ((lenR + lenS + 6) !== buffer.length) throw new Error('Invalid DER encoding (2)') if ((lenR + lenS + 6) !== buffer.length) throw new Error('Invalid DER encoding (2)')
// Negative numbers are not allowed for R.
if (buffer[4] & 0x80) throw new Error('R value is negative') if (buffer[4] & 0x80) throw new Error('R value is negative')
// Null bytes at the start of R are not allowed, unless R would
// otherwise be interpreted as a negative number.
if (lenR > 1 && (buffer[4] === 0x00) && !(buffer[5] & 0x80)) throw new Error('R value excessively padded') if (lenR > 1 && (buffer[4] === 0x00) && !(buffer[5] & 0x80)) throw new Error('R value excessively padded')
// Negative numbers are not allowed for S.
if (buffer[lenR + 6] & 0x80) throw new Error('S value is negative') if (buffer[lenR + 6] & 0x80) throw new Error('S value is negative')
// Null bytes at the start of S are not allowed, unless S would otherwise be
// interpreted as a negative number.
if (lenS > 1 && (buffer[lenR + 6] === 0x00) && !(buffer[lenR + 7] & 0x80)) throw new Error('S value excessively padded') if (lenS > 1 && (buffer[lenR + 6] === 0x00) && !(buffer[lenR + 7] & 0x80)) throw new Error('S value excessively padded')
// non-BIP66 - extract R, S values // non-BIP66 - extract R, S values