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123
sdk/src/main/java/network/xyo/client/account/recoverAddress.kt
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,123 @@ | ||
| package network.xyo.client.account | ||
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| import android.os.Build | ||
| import androidx.annotation.RequiresApi | ||
| import org.spongycastle.jcajce.provider.digest.Keccak | ||
| import java.math.BigInteger | ||
| import kotlin.experimental.xor | ||
|
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| // Secp256k1 curve parameters | ||
| val P = BigInteger("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F", 16) | ||
| val A = BigInteger.ZERO | ||
| val B = BigInteger.valueOf(7) | ||
| val N = BigInteger("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141", 16) | ||
| val Gx = BigInteger("79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798", 16) | ||
| val Gy = BigInteger("483ADA7726A3C4655DA4FBFC0E1108A8FD17B448A68554199C47D08FFB10D4B8", 16) | ||
|
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| // Elliptic curve point structure | ||
| data class Point(val x: BigInteger, val y: BigInteger) { | ||
| fun isAtInfinity() = x == BigInteger.ZERO && y == BigInteger.ZERO | ||
| } | ||
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| fun ByteArray.padStart(targetLength: Int, padValue: Byte = 0): ByteArray { | ||
| if (this.size >= targetLength) return this | ||
| val padding = ByteArray(targetLength - this.size) { padValue } | ||
| return padding + this | ||
| } | ||
|
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| // Double and Add algorithm for point multiplication | ||
| @RequiresApi(Build.VERSION_CODES.TIRAMISU) | ||
| fun pointMultiply(k: BigInteger, point: Point): Point { | ||
| var result = Point(BigInteger.ZERO, BigInteger.ZERO) // Infinity point | ||
| var addend = point | ||
| var scalar = k | ||
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| while (scalar > BigInteger.ZERO) { | ||
| if (scalar.and(BigInteger.ONE) == BigInteger.ONE) { | ||
| result = pointAdd(result, addend) | ||
| } | ||
| addend = pointDouble(addend) | ||
| scalar = scalar.shiftRight(1) | ||
| } | ||
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| return result | ||
| } | ||
|
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| // Point addition on the elliptic curve | ||
| @RequiresApi(Build.VERSION_CODES.TIRAMISU) | ||
| fun pointAdd(p: Point, q: Point): Point { | ||
| if (p.isAtInfinity()) return q | ||
| if (q.isAtInfinity()) return p | ||
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| val slope = if (p.x == q.x) { | ||
| if ((p.y + q.y).mod(P) == BigInteger.ZERO) return Point(BigInteger.ZERO, BigInteger.ZERO) | ||
| (BigInteger.valueOf(3) * p.x.pow(2) + A).mod(P) * (BigInteger.TWO * p.y).modInverse(P) | ||
| } else { | ||
| (q.y - p.y).mod(P) * (q.x - p.x).modInverse(P) | ||
| }.mod(P) | ||
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| val xR = (slope.pow(2) - p.x - q.x).mod(P) | ||
| val yR = (slope * (p.x - xR) - p.y).mod(P) | ||
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| return Point(xR, yR) | ||
| } | ||
|
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| // Point doubling on the elliptic curve | ||
| @RequiresApi(Build.VERSION_CODES.TIRAMISU) | ||
| fun pointDouble(p: Point): Point = pointAdd(p, p) | ||
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| // Recover public key from signature | ||
| @RequiresApi(Build.VERSION_CODES.TIRAMISU) | ||
| fun recoverPublicKey(messageHash: BigInteger, r: BigInteger, s: BigInteger, v: Int): Point? { | ||
| val isYEven = (v % 2 == 0) | ||
| val x = r.add(N.multiply(BigInteger.valueOf((v / 2).toLong()))) | ||
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| if (x >= P) return null | ||
|
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| // Calculate y-coordinate | ||
| val alpha = (x.pow(3) + A * x + B).mod(P) | ||
| val beta = alpha.modPow((P + BigInteger.ONE).shiftRight(2), P) | ||
| val y = if (beta.testBit(0) == isYEven) beta else P - beta | ||
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| val rPoint = Point(x, y) | ||
|
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| // Calculate e and r^-1 | ||
| val e = messageHash | ||
| val rInv = r.modInverse(N) | ||
|
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| // Public key Q = r^-1 * (s * R - e * G) | ||
| val sR = pointMultiply(s, rPoint) | ||
| val eG = pointMultiply(e, Point(Gx, Gy)) | ||
|
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| return pointMultiply(rInv, pointAdd(sR, Point(eG.x, P - eG.y))) | ||
| } | ||
|
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| private fun toKeccak(bytes: ByteArray): ByteArray { | ||
| val keccak = Keccak.Digest256() | ||
| keccak.update(bytes) | ||
| return keccak.digest() | ||
| } | ||
|
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| // Convert public key to Ethereum address | ||
| fun publicKeyToAddress(publicKey: ByteArray): ByteArray { | ||
| val hash = toKeccak(publicKey.sliceArray(1 until publicKey.size)) | ||
| return hash.sliceArray(12 until hash.size) | ||
| } | ||
|
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| // Main function to recover address | ||
| @RequiresApi(Build.VERSION_CODES.TIRAMISU) | ||
| fun recoverPublicKey(messageHash: ByteArray, signature: ByteArray): ByteArray? { | ||
| if (signature.size != 64) return null | ||
|
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| val r = BigInteger(1, signature.copyOfRange(0, 32)) | ||
| val s = BigInteger(1, signature.copyOfRange(32, 64)) | ||
| val v = 0 | ||
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| val messageHashBI = BigInteger(1, messageHash) | ||
|
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| val publicPoint = recoverPublicKey(messageHashBI, r, s, v) ?: return null | ||
| val uncompressedKey = | ||
| publicPoint.x.toByteArray().padStart(32, 0) + | ||
| publicPoint.y.toByteArray().padStart(32, 0) | ||
| return uncompressedKey | ||
| } |