How to decode the SHA256 fingerprint from X509Certificate in Kotlin without third library usage in hex.

X509Certificate get SHA256

CodePudding user response：

you can use the MessageDigest from Java Security API

import java.security.MessageDigest
import java.security.cert.X509Certificate

fun decodeSHA256Fingerprint(cert: X509Certificate): String {
    val sha256 = MessageDigest.getInstance("SHA-256")
    val fingerprint = sha256.digest(cert.encoded)
    return fingerprint.joinToString(separator = "") { String.format("x", it) }
}