Spongy Castle（Bouncy Castle distribution）を使用して、有効なECDSA secp256r1/prime256v1鍵ペアをAndroidで生成する

Question

AndroidでSpongyCastleを使用してECDSA鍵ペアを生成しようとしています。

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とプライベートキー：：私は常に 公開鍵の例のような何かを得るため、

static { 
    Security.insertProviderAt(new org.spongycastle.jce.provider.BouncyCastleProvider(), 1); 
} 

public static KeyPair generate() { 
     ECParameterSpec ecSpec = ECNamedCurveTable.getParameterSpec("prime256v1"); 
     KeyPairGenerator generator = KeyPairGenerator.getInstance("ECDSA", "SC"); 
     generator.initialize(ecSpec, new SecureRandom()); 
     KeyPair keyPair = g.generateKeyPair(); 
     Log.i(TAG, "EC Pub Key generated: " + utils.bytesToHex(keyPair.getPublic().getEncoded())); 
     Log.i(TAG, "EC Private Key generated: " + utils.bytesToHex(keyPair.getPrivate().getEncoded()));    
     return generator.generateKeyPair(); 
} 

何かが間違っている：

これはコードです0

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サイトECDSA sampleが無効にECDSA署名を与え、彼らはその小さな秘密鍵から、実際には非常に異なると常に同じサイトで生成された「04」の公開鍵で始まるようです。

はまた、私のバックエンドの検証は私にエラー「無効なポイントエンコーディング0x30の」

を与えるバックエンドのJavaメソッドのチェックがある：デコードされたバイト配列または進文字列に公開鍵を生成し

public ECPublicKey getPublicKeyFromHex(String publicKeyHex) 
     throws NoSuchAlgorithmException, DecoderException, ApplicationGenericException { 
    byte[] rawPublicKey = Hex.decodeHex(publicKeyHex.toCharArray()); 
    ECPublicKey ecPublicKey = null; 
    KeyFactory kf = null; 

    ECNamedCurveParameterSpec ecNamedCurveParameterSpec = ECNamedCurveTable.getParameterSpec("prime256v1"); 
    ECCurve curve = ecNamedCurveParameterSpec.getCurve(); 
    EllipticCurve ellipticCurve = EC5Util.convertCurve(curve, ecNamedCurveParameterSpec.getSeed()); 
    java.security.spec.ECPoint ecPoint = ECPointUtil.decodePoint(ellipticCurve, rawPublicKey); 
    java.security.spec.ECParameterSpec ecParameterSpec = EC5Util.convertSpec(ellipticCurve, 
      ecNamedCurveParameterSpec); 
    java.security.spec.ECPublicKeySpec publicKeySpec = new java.security.spec.ECPublicKeySpec(ecPoint, 
      ecParameterSpec); 

    kf = KeyFactory.getInstance("ECDSA", new BouncyCastleProvider()); 

    try { 
     ecPublicKey = (ECPublicKey) kf.generatePublic(publicKeySpec); 
    } catch (Exception e) { 
     throw new ApplicationGenericException(e.getMessage(), e.getCause()); 
    } 

    return ecPublicKey; 
} 

Answer 1

変換：

public String getPublicKeyAsHex(PublicKey publicKey){ 

    ECPublicKey ecPublicKey = (ECPublicKey)publicKey; 
    ECPoint ecPoint = ecPublicKey.getW(); 

    byte[] publicKeyBytes = new byte[PUBLIC_KEY_LENGTH]; 
    writeToStream(publicKeyBytes, 0, ecPoint.getAffineX(), PRIVATE_KEY_LENGTH); 
    writeToStream(publicKeyBytes, PRIVATE_KEY_LENGTH, ecPoint.getAffineY(), PRIVATE_KEY_LENGTH); 

    String hex = Hex.toHexString(publicKeyBytes); 

    logger.debug("Public key bytes: " + Arrays.toString(publicKeyBytes)); 
    logger.debug("Public key hex: " + hex); 

    return hex; 
} 

private void writeToStream(byte[] stream, int start, BigInteger value, int size) { 
    byte[] data = value.toByteArray(); 
    int length = Math.min(size, data.length); 
    int writeStart = start + size - length; 
    int readStart = data.length - length; 
    System.arraycopy(data, readStart, stream, writeStart, length); 
} 

変換バックPublicKeyバイト配列をデコード：

KeyFactory factory = KeyFactory.getInstance(ALGORITHM, ALGORITHM_PROVIDER); 

ECNamedCurveParameterSpec spec = ECNamedCurveTable.getParameterSpec(CURVE); 

ECNamedCurveSpec params = new ECNamedCurveSpec(CURVE, spec.getCurve(), spec.getG(), spec.getN()); 

BigInteger xCoordinate = new BigInteger(1, Arrays.copyOfRange(decodedPublicKey, 0, PRIVATE_KEY_LENGTH)); 
BigInteger yCoordinate = new BigInteger(1, Arrays.copyOfRange(decodedPublicKey, PRIVATE_KEY_LENGTH, PUBLIC_KEY_LENGTH)); 
java.security.spec.ECPoint w = new java.security.spec.ECPoint(xCoordinate, yCoordinate); 

PublicKey encodedPublicKey = factory.generatePublic(new java.security.spec.ECPublicKeySpec(w, params));