RSA密码的大型输入

Question

我已经在Android中生成了以下公钥。

 fun createCipher(): Cipher
    {
        val posKey = posPublicKey
        posKey.publicKey.modulus

        var spec = RSAPublicKeySpec(BigInteger(posPublicKey.html" target="_blank">publicKey.modulus), BigInteger(posPublicKey.publicKey.exponent))
        var fact = KeyFactory.getInstance(KeyProperties.KEY_ALGORITHM_RSA)

        publicKey = fact.generatePublic(spec)
        var cipher = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding")
        cipher.init(Cipher.ENCRYPT_MODE, publicKey)
        return cipher
    }

我选择的RSA密钥大小是4096字节，指数是3字节，模数是512字节

模数字节数组如下所示：

[-32, -28, -121, 32, 109, -82, 43, 115, 43, -117, 20, 35, 122, 33, -2, 23, 23, -22, 75, 0, 91, 10, -89, 48, 33, -89, 57, 1, 57, -13, 9, -127, 90, 121, -96, -94, 106, -16, -105, -112, -74, 30, -12, 74, -74, 104, -26, 15, 99, -22, -55, -75, 14, -45, 56, 20, 85, 90, 83, -50, 68, -114, 5, -10, -109, 79, 44, 81, 68, -98, -45, -51, -97, 71, 90, -13, -78, 118, -21, -47, 66, 104, -83, 56, -72, -27, 45, 16, 70, 32, -76, -125, -11, 108, 126, -61, -126, 16, 6, -49, -106, -114, 18, 49, 121, -39, -109, 115, 111, -128, 83, 8, -110, -10, -4, 51, -67, 49, 66, 103, -76, -88, -110, 122, 56, 29, -101, 22, 3, 117, -104, -54, -64, -71, 23, 58, 87, 37, 96, 25, -114, 38, 1, -126, 33, -91, -4, 89, -28, 10, 95, -104, -24, -38, 17, 47, -122, 24, -89, 123, 100, 12, -10, -57, -44, 45, 25, 39, -80, -101, -6, -99, -95, -5, 70, 32, 37, -57, -52, -47, -66, 85, 10, -48, 75, 4, -114, 104, -7, -112, -128, 4, 114, 77, -40, 96, 66, 83, -54, 10, 111, 102, -39, -63, 2, -75, 38, 36, 24, 13, -51, 96, 89, -60, -40, 99, 65, 123, 52, -114, 122, 75, 32, -121, 80, -76, -11, -1, -31, -118, -51, -21, 13, 109, 111, -102, 120, -56, 62, -19, -79, 86, -41, -81, 67, -80, -63, 37, 35, 47, 109, -32, 47, -128, 95, -48, -53, -1, -125, -19, -9, -10, 15, -116, -50, 53, -86, -102, -24, 107, 122, -43, -125, 51, 14, 101, 67, 57, 116, 97, -40, -98, -82, -118, -83, 120, -107, -14, 19, -49, -27, 10, 25, 40, 43, -27, 31, 59, -57, 58, 33, -98, 1, -45, -118, 76, -21, -13, -123, 67, 42, -37, -96, -32, 33, 124, 1, 44, -99, 74, 18, 32, 10, -107, -121, 86, -115, -70, -107, 109, 17, -92, 109, -47, 60, -49, -91, 7, -125, 47, 78, 86, 81, -2, -35, 17, 124, 94, -26, -80, -84, 120, 110, 38, -55, -90, -11, 107, 73, 71, 44, 69, -58, 56, -59, 2, 94, 27, 88, 29, -57, 95, -99, 5, 102, -66, 118, -82, 126, 20, -104, -95, 47, -2, 77, -33, 89, -66, -92, 121, -5, 78, 68, -1, -82, -95, -121, 117, -29, 70, 11, -72, 54, -99, -13, -87, 9, 77, -113, 51, -124, -56, -8, 126, -114, -31, 90, -125, -11, 41, -85, 74, 3, 90, -95, 85, 121, 61, 14, 116, 51, -40, -57, -124, -69, -51, -76, -119, -80, 95, 95, 17, -34, 80, -36, 66, -51, 14, -69, -113, 35, -109, -115, -16, -3, -118, 114, -20, -81, 57, -65, 40, -8, -67, -85, 110, 50, -128, 44, -78, 93, -44, -93, 89, -76, 13, 98, -38, -55, -120, 11, 127, 84, -2, 101, 57, -121, -111, 91, -102, -118, 85, -124, -90, 91, -84, 28, 120, -28, -105, 88, -73, 6, 89, 33, 8, 9, 30, 9, -6, 17, 25]

指数字节数组如下所示：

[1, 0, 1]

测试密钥如下：

val stringKey = "8D-F7-5B-15-0F-2A-E5-3E-FD-44-5A-63-50-AC-62-D6-06-2D-59-5C-F1-C3-9A-DB-45-25-0D-7A-72-AE-DF-87"
val stringIV = "FA-94-FD-74-2E-AC-2C-90-79-98-AF-A3-D7-12-5D-A2"

 var aeskey = AesKeyBuilder()
            val key = (stringKey.replace("-", "")).toByteArray(Charsets.US_ASCII)

            val iv = (stringIV.replace("-", "")).toByteArray(Charsets.US_ASCII)
            aeskey.key = key
            aeskey.iv = iv

val encryptedKey = cipher.doFinal(aesKey.Key)

我试图加密的项目是64字节。使用此公钥。

但是，我得到了以下错误：

Process: com.touchsides.rewards.debug, PID: 19470
com.android.org.bouncycastle.crypto.DataLengthException: input too large for RSA cipher.
    at com.android.org.bouncycastle.crypto.engines.RSACoreEngine.convertInput(RSACoreEngine.java:115)
    at com.android.org.bouncycastle.crypto.engines.RSABlindedEngine.processBlock(RSABlindedEngine.java:95)
    at com.android.org.bouncycastle.crypto.encodings.OAEPEncoding.encodeBlock(OAEPEncoding.java:199)
    at com.android.org.bouncycastle.crypto.encodings.OAEPEncoding.processBlock(OAEPEncoding.java:131)

我相信模的大小足够大，可以对这个字节数组进行加密。

Answer 1

你会得到com.Android组织。蹦蹦跳跳。加密。数据长度异常错误，因为RSA密钥是用负模创建的。所以它甚至不能用来加密一个字节。

默认构造函数使用提供的字节数组有效载荷的最高有效位作为数字的符号位。因此，您必须使用另一个构造函数显式指定您想要一个正数，其中第一个参数是符号指示符：

BigInteger(1, posPublicKey.publicKey.modulus), BigInteger(1, posPublicKey.publicKey.exponent)

还有一种C#方法可以在字节数组前面添加一个零字节（因此符号位将始终为零）：

BigInteger(byteArrayOf(0) + posPublicKey.publicKey.modulus), BigInteger(byteArrayOf(0) + posPublicKey.publicKey.exponent)

最后，如果你已经用错误的方式创建了你的BigInteger，可以将其转换为：

var modulus = BigInteger(posPublicKey.publicKey.modulus)
if (modulus.compareTo(BigInteger.ZERO) < 0)
    modulus = modulus.add(BigInteger.ONE.shiftLeft(4096))

也请大家看看这个答案和这个问题的答案。