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Merge pull request #219 from yenom/Sajjon/expose-ec-methods
Adding EC point multiplication method
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,79 @@ | ||
| // | ||
| // PointOnCurve.swift | ||
| // BitcoinKit | ||
| // | ||
| // Created by Alexander Cyon on 2019-03-21. | ||
| // Copyright © 2019 BitcoinKit developers. All rights reserved. | ||
| // | ||
|
|
||
| import Foundation | ||
| #if BitcoinKitXcode | ||
| import BitcoinKit.Private | ||
| #else | ||
| import BitcoinKitPrivate | ||
| #endif | ||
|
|
||
| public struct PointOnCurve { | ||
|
|
||
| private static let byteForUncompressed: UInt8 = 0x04 | ||
| public let x: Scalar32Bytes | ||
| public let y: Scalar32Bytes | ||
|
|
||
| public init(x: Scalar32Bytes, y: Scalar32Bytes) { | ||
| self.x = x | ||
| self.y = y | ||
| } | ||
|
|
||
| init(x xData: Data, y yData: Data) throws { | ||
| let x = try Scalar32Bytes(data: xData) | ||
| let y = try Scalar32Bytes(data: yData) | ||
| self.init(x: x, y: y) | ||
| } | ||
| } | ||
|
|
||
| public extension PointOnCurve { | ||
| enum Error: Swift.Error { | ||
| case multiplicationResultedInTooFewBytes(expected: Int, butGot: Int) | ||
| case expectedUncompressedPoint | ||
| case publicKeyContainsTooFewBytes(expected: Int, butGot: Int) | ||
| } | ||
|
|
||
| static func decodePointFromPublicKey(_ publicKey: PublicKey) throws -> PointOnCurve { | ||
| let data: Data | ||
| if publicKey.isCompressed { | ||
| data = _EllipticCurve.decodePointOnCurve(forCompressedPublicKey: publicKey.data) | ||
| } else { | ||
| data = publicKey.data | ||
| } | ||
| return try PointOnCurve.decodePointFrom(xAndYPrefixedWithCompressionType: data) | ||
| } | ||
|
|
||
| private static func decodePointFrom(xAndYPrefixedWithCompressionType data: Data) throws -> PointOnCurve { | ||
| var xAndY = data | ||
| guard xAndY[0] == PointOnCurve.byteForUncompressed else { | ||
| throw Error.expectedUncompressedPoint | ||
| } | ||
| xAndY = Data(xAndY.dropFirst()) | ||
| let expectedByteCount = Scalar32Bytes.expectedByteCount * 2 | ||
| guard xAndY.count == expectedByteCount else { | ||
| throw Error.multiplicationResultedInTooFewBytes(expected: expectedByteCount, butGot: xAndY.count) | ||
| } | ||
| let resultX = xAndY.prefix(Scalar32Bytes.expectedByteCount) | ||
| let resultY = xAndY.suffix(Scalar32Bytes.expectedByteCount) | ||
| return try PointOnCurve(x: resultX, y: resultY) | ||
| } | ||
|
|
||
| func multiplyBy(scalar: Scalar32Bytes) throws -> PointOnCurve { | ||
| let xAndY = _EllipticCurve.multiplyECPointX(x.data, andECPointY: y.data, withScalar: scalar.data) | ||
| return try PointOnCurve.decodePointFrom(xAndYPrefixedWithCompressionType: xAndY) | ||
| } | ||
|
|
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| func multiplyBy(privateKey: PrivateKey) throws -> PointOnCurve { | ||
| return try multiplyBy(scalar: privateKey.data) | ||
| } | ||
|
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| func multiplyBy(scalar scalarData: Data) throws -> PointOnCurve { | ||
| let scalar = try Scalar32Bytes(data: scalarData) | ||
| return try multiplyBy(scalar: scalar) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,24 @@ | ||
| // | ||
| // Scalar32Bytes.swift | ||
| // BitcoinKit | ||
| // | ||
| // Created by Alexander Cyon on 2019-03-21. | ||
| // Copyright © 2019 BitcoinKit developers. All rights reserved. | ||
| // | ||
|
|
||
| import Foundation | ||
|
|
||
| public struct Scalar32Bytes { | ||
| public enum Error: Swift.Error { | ||
| case tooManyBytes(expectedCount: Int, butGot: Int) | ||
| } | ||
| public static let expectedByteCount = 32 | ||
| public let data: Data | ||
| public init(data: Data) throws { | ||
| let byteCount = data.count | ||
| if byteCount > Scalar32Bytes.expectedByteCount { | ||
| throw Error.tooManyBytes(expectedCount: Scalar32Bytes.expectedByteCount, butGot: byteCount) | ||
| } | ||
| self.data = data | ||
| } | ||
| } |
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