So, I've been trying to inter-operate with CryptoKit, and my backend running on Linux, and it appears that the documentation here is incorrect. It claims that the data is first digested with SHA256, but my testing seems to say that the convenience Data functions is actually done with SHA512
import CryptoKit
import Foundation
typealias Key = P521.Signing.PrivateKey
func verify1() throws {
let key = Key()
let data = "1 2 3 4 5 6 7 8 9 0".data(using: .ascii)!
let digest = SHA256.hash(data: data)
let signature = try key.signature(for: digest)
let verified = key.publicKey.isValidSignature(signature, for: data)
print("verified \(verified)")
}
func verify2() throws {
let key = Key()
let data = "1 2 3 4 5 6 7 8 9 0".data(using: .ascii)!
let digest = SHA512.hash(data: data)
let signature = try key.signature(for: digest)
let verified = key.publicKey.isValidSignature(signature, for: data)
print("verified \(verified)")
}
func main() {
do {
try verify1()
try verify2()
}
catch {
print(error.localizedDescription)
}
}
main()
(My Generic-Fu was insufficient to avoid the copy paste)
When the above is run on my machine I get:
% swift test.swift
verified false
verified true
Is my diagnosis correct?
