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misc: ecdsa raw signature #1457

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Merged
merged 10 commits into from
Nov 6, 2025
Merged

misc: ecdsa raw signature #1457

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1e9f2a5
add ecdsa raw signature
xinsong-cui Nov 4, 2025
c171b30
lint
xinsong-cui Nov 4, 2025
8ee1fbf
add native implementation
xinsong-cui Nov 4, 2025
bb849dc
pr feedback
xinsong-cui Nov 4, 2025
dc4ba74
remove jvm test
xinsong-cui Nov 4, 2025
79d9a60
cleanup
xinsong-cui Nov 4, 2025
ff8fe78
lint
xinsong-cui Nov 4, 2025
2dc6f6f
unit test
xinsong-cui Nov 5, 2025
17215bb
update test
xinsong-cui Nov 5, 2025
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add comment
xinsong-cui Nov 5, 2025
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4 changes: 4 additions & 0 deletions runtime/runtime-core/api/runtime-core.api
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Original file line number Diff line number Diff line change
Expand Up @@ -729,6 +729,10 @@ public final class aws/smithy/kotlin/runtime/hashing/EcdsaJVMKt {
public static final fun ecdsaSecp256r1 ([B[B)[B
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@xinsong-cui xinsong-cui Nov 4, 2025 •
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Existing ecdsaSecp256r1(key, message) calls work unchanged, should not be a breaking change

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@ianbotsf ianbotsf Nov 4, 2025

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This is definitely a breaking change because you've altered the method signature. Older consumers of runtime-core will encounter a NoSuchMethodError exception at runtime. The only way to do this safely without breaking binary compatibility is to maintain the old method signature and add a new one.

I recommend one of the following approaches:

  • Expose a new method ecdsaSecp256r1Rs which invokes ecdsaSecp256r1Rs and extracts the r and s values. This could be implemented in common since it's just byte manipulation
  • Expose a new method asn1DerToRs which converts any ByteArray from ASN.1 DER format to r||s. Callers would then invoke ecdsaSecp256r1Rs first and then asn1DerToRs. This could also be implemented in common.

}

public final class aws/smithy/kotlin/runtime/hashing/EcdsaKt {
public static final fun ecdsaSecp256r1Rs ([B[B)[B
}

public abstract interface class aws/smithy/kotlin/runtime/hashing/HashFunction {
public abstract fun digest ()[B
public abstract fun getBlockSizeBytes ()I
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37 changes: 36 additions & 1 deletion runtime/runtime-core/common/src/aws/smithy/kotlin/runtime/hashing/Ecdsa.kt
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Expand Up @@ -5,6 +5,41 @@
package aws.smithy.kotlin.runtime.hashing

/**
* ECDSA on the SECP256R1 curve.
* ECDSA on the SECP256R1 curve returning ASN.1 DER format.
*/
public expect fun ecdsaSecp256r1(key: ByteArray, message: ByteArray): ByteArray

/**
* ECDSA on the SECP256R1 curve returning raw r||s format.
*/
public fun ecdsaSecp256r1Rs(key: ByteArray, message: ByteArray): ByteArray {
val derSignature = ecdsaSecp256r1(key, message)
return parseDerSignature(derSignature)
}
Comment on lines +12 to +18
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@lauzadis lauzadis Nov 4, 2025

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Can we create some unit tests for this?

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@xinsong-cui xinsong-cui Nov 5, 2025

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Yes, tests added.
Note: I have to disable signature verification test on JVM8 since SHA256withECDSAinP1363Format is not supported


/**
* Parses an ASN.1 DER encoded ECDSA signature and converts it to raw r||s format.
*/
private fun parseDerSignature(derSignature: ByteArray): ByteArray {
var index = 2 // Skip SEQUENCE tag and length

// Read r
index++ // Skip INTEGER tag
val rLength = derSignature[index++].toInt() and 0xFF
val r = derSignature.sliceArray(index until index + rLength)
index += rLength

// Read s
index++ // Skip INTEGER tag
val sLength = derSignature[index++].toInt() and 0xFF
val s = derSignature.sliceArray(index until index + sLength)

// Remove leading zero bytes and pad to 32 bytes
val rFixed = r.dropWhile { it == 0.toByte() }.toByteArray()
val sFixed = s.dropWhile { it == 0.toByte() }.toByteArray()

val rPadded = if (rFixed.size < 32) ByteArray(32 - rFixed.size) + rFixed else rFixed
val sPadded = if (sFixed.size < 32) ByteArray(32 - sFixed.size) + sFixed else sFixed

return rPadded + sPadded
}
39 changes: 39 additions & 0 deletions runtime/runtime-core/jvm/test/aws/smithy/kotlin/runtime/hashing/EcdsaJVMTest.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,8 @@ package aws.smithy.kotlin.runtime.hashing

import org.junit.jupiter.api.Assertions.assertFalse
import org.junit.jupiter.api.Assertions.assertTrue
import org.junit.jupiter.api.condition.EnabledForJreRange
import org.junit.jupiter.api.condition.JRE
import java.security.*
import java.security.interfaces.*
import java.security.spec.*
Expand All @@ -30,6 +32,10 @@ class EcdsaJVMTest {

assertTrue(signature.isNotEmpty())
assertTrue(signature.size >= 64) // ECDSA signatures are typically 70-72 bytes in DER format

val rawSignature = ecdsaSecp256r1Rs(privateKey, message)
assertTrue(signature.isNotEmpty())
assertTrue(rawSignature.size == 64)
}

@Test
Expand All @@ -44,6 +50,13 @@ class EcdsaJVMTest {
assertTrue(signature1.isNotEmpty())
assertTrue(signature2.isNotEmpty())
assertFalse(signature1.contentEquals(signature2))

val rawSignature1 = ecdsaSecp256r1Rs(privateKey, message1)
val rawSignature2 = ecdsaSecp256r1Rs(privateKey, message2)

assertTrue(rawSignature1.isNotEmpty())
assertTrue(rawSignature2.isNotEmpty())
assertFalse(rawSignature1.contentEquals(rawSignature2))
}

@Test
Expand All @@ -53,6 +66,9 @@ class EcdsaJVMTest {

val signature = ecdsaSecp256r1(privateKey, message)
assertTrue(signature.isNotEmpty())

val rawSignature = ecdsaSecp256r1Rs(privateKey, message)
assertTrue(rawSignature.isNotEmpty())
}

@Test
Expand All @@ -62,6 +78,9 @@ class EcdsaJVMTest {

val signature = ecdsaSecp256r1(privateKey, largeMessage)
assertTrue(signature.isNotEmpty())

val rawSignature = ecdsaSecp256r1Rs(privateKey, largeMessage)
assertTrue(rawSignature.isNotEmpty())
}

@Test
Expand All @@ -81,4 +100,24 @@ class EcdsaJVMTest {

assertTrue(verifier.verify(signature))
}

@Test
// SHA256withECDSAinP1363Format algorithm was introduced in Java 11, skip on Java 8
@EnabledForJreRange(min = JRE.JAVA_11)
fun testVerifyRawSignature() {
val keyGen = KeyPairGenerator.getInstance("EC")
keyGen.initialize(ECGenParameterSpec("secp256r1"))
val keyPair = keyGen.generateKeyPair()
val privateKey = (keyPair.private as ECPrivateKey).s.toByteArray()
val publicKey = keyPair.public

val message = "Hello, World!".toByteArray()
val signature = ecdsaSecp256r1Rs(privateKey, message)

val verifier = Signature.getInstance("SHA256withECDSAinP1363Format")
verifier.initVerify(publicKey)
verifier.update(message)

assertTrue(verifier.verify(signature))
}
}
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