Can't read OpenSSL-generated ECDSA key from Java: InvalidKeySpecException

问题

I created an ECDSA keypair and exported the public key using OpenSSL, but I'm unable to read the public key in from Java.

Key generation in OpenSSL:

$ openssl ecparam -name secp256k1 -genkey -noout -outform DER | openssl ec -inform DER -pubout -outform DER > secp256k1.public.der

Clojure code that reads a key in from file, with [org.bouncycastle/bcprov-jdk15on "1.56"] as a dependency:

(ns adhoc.ecdsa-mismatch
  (:import (java.nio.file Files Paths)
           (java.security Security KeyFactory)
           (java.security.spec X509EncodedKeySpec)))

(when (nil? (Security/getProvider "BC"))
  (Security/addProvider (org.bouncycastle.jce.provider.BouncyCastleProvider.)))

(defn read-bytes
  "Read file from path as byte array."
  [^String path]
  (Files/readAllBytes (Paths/get path (into-array String []))))

(defn read-pubkey
  [^String path]
  (.generatePublic (KeyFactory/getInstance "ECDSA" "BC")
                   (X509EncodedKeySpec. (read-bytes path))))

(require '[adhoc.ecdsa-mismatch :as mm])

(mm/read-pubkey "secp256k1.public.der")
;; InvalidKeySpecException java.lang.NullPointerException  org.bouncycastle.jce.provider.JDKKeyFactory$EC.engineGeneratePublic (:-1)

(.printStackTrace *e)
;; java.security.spec.InvalidKeySpecException: java.lang.NullPointerException
;;  at org.bouncycastle.jce.provider.JDKKeyFactory$EC.engineGeneratePublic(Unknown Source)
;;  at java.security.KeyFactory.generatePublic(KeyFactory.java:328)
;;  at adhoc.ecdsa_mismatch$read_pubkey.invokeStatic(ecdsa_mismatch.clj:16)
;;  at adhoc.ecdsa_mismatch$read_pubkey.invoke(ecdsa_mismatch.clj:14)

Additional info

Generating a key with the NIST P-256 curve:

$ openssl ecparam -name prime256v1 -genkey -noout -outform DER | openssl ec -inform DER -pubout -outform DER > prime256v1.public.der

Loading a prime256v1 from disk:

(println (mm/read-pubkey "prime256v1.public.der"))
;; #object[org.bouncycastle.jce.provider.JCEECPublicKey 0x72369051 EC Public Key
;;             X: 5a690a647dc4b7e80f71f15212b08686c1f717ada7198fa8a0b8c93cec16ecb
;;             Y: 30be46137f328766ef8686675f118760ab0c96c52275bf00cf56097333ea6487
;; ]

The contents of the public keys:

$ base64 secp256k1.public.der 
MFYwEAYHKoZIzj0CAQYFK4EEAAoDQgAEsipNgzBpQ0CLgZNw+LhASmh4KmGXnJsOC2dfzq5cVwMn
HfsfHGphaGvZTNoc/lUVrr+ICFK/2D/9up9hHHHHWg==
$ base64 prime256v1.public.der 
MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEBaaQpkfcS36A9x8VISsIaGwfcXracZj6iguMk87B
bsswvkYTfzKHZu+GhmdfEYdgqwyWxSJ1vwDPVglzM+pkhw==

回答1:

The solution is that Java -- or perhaps this version of BouncyCastle -- does not support the secp256k1 elliptic curve! Using the far more common curve prime256v1 (NIST P-256) in the openssl call produces a key that I can read.

Sample successful output:

#<JCEECPublicKey EC Public Key
            X: 89cfd7dfb455e6ea51e578e9ea3505ba1e44a0a5f126e3b280611cf6bb467653
            Y: 565eb189ef15b8ff1b72824a7f0418a7df205797a86c8f30961e9bf0deaaa0c3
>

来源：https://stackoverflow.com/questions/42234685/cant-read-openssl-generated-ecdsa-key-from-java-invalidkeyspecexception

标签

java

OpenSSL

cryptography

ecdsa