IllegalBlockSizeException when Decrypt String by RSA 2048 Private Key

I was trying to decrypt the string by RSA 2048 private key, but the error below is occurred.

java.lang.RuntimeException: java.lang.reflect.InvocationTargetException

        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811)

     Caused by: java.lang.reflect.InvocationTargetException

        at java.lang.reflect.Method.invoke(Native Method)

        at java.lang.reflect.Method.invoke(Method.java:372)

        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1016)

        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811) 

     Caused by: javax.crypto.IllegalBlockSizeException: input must be under 256 bytes

        at com.android.org.conscrypt.OpenSSLCipherRSA.engineDoFinal(OpenSSLCipherRSA.java:245)

        at javax.crypto.Cipher.doFinal(Cipher.java:1340)

Here is my code:

private fun rsaDecrypt(key: String, plain: String): String {

    var privateKey = ""

    if (key.contains("-----BEGIN RSA PRIVATE KEY-----") || key.contains("-----END RSA PRIVATE KEY-----")) {

        privateKey = key.replace("-----BEGIN RSA PRIVATE KEY-----", "").replace("-----END RSA PRIVATE KEY-----", "")

    }



    val base64Key = Base64.decode(privateKey.toByteArray(Charsets.UTF_8), Base64.DEFAULT)

    val spec = PKCS8EncodedKeySpec(base64Key)

    val keyFactory = KeyFactory.getInstance("RSA", "BC")

    val rsaPrivateKey = keyFactory.generatePrivate(spec)



    val cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding")

    cipher.init(Cipher.DECRYPT_MODE, rsaPrivateKey)

    val decryptedBytes = cipher.doFinal(plain.toByteArray(Charsets.UTF_8))



    return Base64.encodeToString(decryptedBytes, Base64.DEFAULT)

}

Encrypted string:

fhTGWW3Zn/nnhXoQO2Y3eKfYkBe/um7XUu2SlrnXMHT7tqT+KvcEUWXnJvLgN7/jpJp8ZOFvHiB6w8OFjPob7VSzQbyultpkFvBGZR7Z6j8m24IoqAPj2OhZDPQ4W8kza4eu/LP2560MfcbJqblOG0tcVF72fQZ2fXKPVRyWv53pDLfxC38+jxdd+49mSTRcl7sfyYvqvW4HVb4IHnwwt+m+1Y4zG7GFxnP+FuywgXmELO1skNCdCHxZ2zopZDtZiBA0vplEkWv18V2lF7SNnaN17SVQQc83yfZnwTQjbfKBWd0HU+4DKtO5ADGJmMCMRV0ceq+BnP141Q45CFDxbQ==

Private key:

How can I decrypt the string?

edited Nov 14 '18 at 14:46

James K Polk

30k116896

asked Nov 14 '18 at 6:28

shisushi

687

refer stackoverflow.com/questions/10007147/…

– sasikumar
Nov 14 '18 at 8:40

With PKCS1Padding adds 11 bytes of padding so a message of the key size will be to large by 11 bytes. See the above comment link.

– zaph
Nov 14 '18 at 8:47

I don't believe that exception is possible with the data you've supplied. First of all, the private is not in PKCS#8 format, so I don't see how your code could've gotten past the keyFactory.generatePrivate(spec) without throwing an exception at that point.

– James K Polk
Nov 14 '18 at 14:54

Well, I actually ran your an almost identical Java version of your code on an Android emulator and worked as is, which was very surprising.

– James K Polk
Nov 14 '18 at 17:55

add a comment |

I was trying to decrypt the string by RSA 2048 private key, but the error below is occurred.

java.lang.RuntimeException: java.lang.reflect.InvocationTargetException

        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811)

     Caused by: java.lang.reflect.InvocationTargetException

        at java.lang.reflect.Method.invoke(Native Method)

        at java.lang.reflect.Method.invoke(Method.java:372)

        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1016)

        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811) 

     Caused by: javax.crypto.IllegalBlockSizeException: input must be under 256 bytes

        at com.android.org.conscrypt.OpenSSLCipherRSA.engineDoFinal(OpenSSLCipherRSA.java:245)

        at javax.crypto.Cipher.doFinal(Cipher.java:1340)

Here is my code:

private fun rsaDecrypt(key: String, plain: String): String {

    var privateKey = ""

    if (key.contains("-----BEGIN RSA PRIVATE KEY-----") || key.contains("-----END RSA PRIVATE KEY-----")) {

        privateKey = key.replace("-----BEGIN RSA PRIVATE KEY-----", "").replace("-----END RSA PRIVATE KEY-----", "")

    }



    val base64Key = Base64.decode(privateKey.toByteArray(Charsets.UTF_8), Base64.DEFAULT)

    val spec = PKCS8EncodedKeySpec(base64Key)

    val keyFactory = KeyFactory.getInstance("RSA", "BC")

    val rsaPrivateKey = keyFactory.generatePrivate(spec)



    val cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding")

    cipher.init(Cipher.DECRYPT_MODE, rsaPrivateKey)

    val decryptedBytes = cipher.doFinal(plain.toByteArray(Charsets.UTF_8))



    return Base64.encodeToString(decryptedBytes, Base64.DEFAULT)

}

Encrypted string:

fhTGWW3Zn/nnhXoQO2Y3eKfYkBe/um7XUu2SlrnXMHT7tqT+KvcEUWXnJvLgN7/jpJp8ZOFvHiB6w8OFjPob7VSzQbyultpkFvBGZR7Z6j8m24IoqAPj2OhZDPQ4W8kza4eu/LP2560MfcbJqblOG0tcVF72fQZ2fXKPVRyWv53pDLfxC38+jxdd+49mSTRcl7sfyYvqvW4HVb4IHnwwt+m+1Y4zG7GFxnP+FuywgXmELO1skNCdCHxZ2zopZDtZiBA0vplEkWv18V2lF7SNnaN17SVQQc83yfZnwTQjbfKBWd0HU+4DKtO5ADGJmMCMRV0ceq+BnP141Q45CFDxbQ==

Private key:

How can I decrypt the string?

edited Nov 14 '18 at 14:46

James K Polk

30k116896

asked Nov 14 '18 at 6:28

shisushi

687

refer stackoverflow.com/questions/10007147/…

– sasikumar
Nov 14 '18 at 8:40

With PKCS1Padding adds 11 bytes of padding so a message of the key size will be to large by 11 bytes. See the above comment link.

– zaph
Nov 14 '18 at 8:47

I don't believe that exception is possible with the data you've supplied. First of all, the private is not in PKCS#8 format, so I don't see how your code could've gotten past the keyFactory.generatePrivate(spec) without throwing an exception at that point.

– James K Polk
Nov 14 '18 at 14:54

Well, I actually ran your an almost identical Java version of your code on an Android emulator and worked as is, which was very surprising.

– James K Polk
Nov 14 '18 at 17:55

add a comment |

I was trying to decrypt the string by RSA 2048 private key, but the error below is occurred.

java.lang.RuntimeException: java.lang.reflect.InvocationTargetException

        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811)

     Caused by: java.lang.reflect.InvocationTargetException

        at java.lang.reflect.Method.invoke(Native Method)

        at java.lang.reflect.Method.invoke(Method.java:372)

        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1016)

        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811) 

     Caused by: javax.crypto.IllegalBlockSizeException: input must be under 256 bytes

        at com.android.org.conscrypt.OpenSSLCipherRSA.engineDoFinal(OpenSSLCipherRSA.java:245)

        at javax.crypto.Cipher.doFinal(Cipher.java:1340)

Here is my code:

private fun rsaDecrypt(key: String, plain: String): String {

    var privateKey = ""

    if (key.contains("-----BEGIN RSA PRIVATE KEY-----") || key.contains("-----END RSA PRIVATE KEY-----")) {

        privateKey = key.replace("-----BEGIN RSA PRIVATE KEY-----", "").replace("-----END RSA PRIVATE KEY-----", "")

    }



    val base64Key = Base64.decode(privateKey.toByteArray(Charsets.UTF_8), Base64.DEFAULT)

    val spec = PKCS8EncodedKeySpec(base64Key)

    val keyFactory = KeyFactory.getInstance("RSA", "BC")

    val rsaPrivateKey = keyFactory.generatePrivate(spec)



    val cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding")

    cipher.init(Cipher.DECRYPT_MODE, rsaPrivateKey)

    val decryptedBytes = cipher.doFinal(plain.toByteArray(Charsets.UTF_8))



    return Base64.encodeToString(decryptedBytes, Base64.DEFAULT)

}

Encrypted string:

fhTGWW3Zn/nnhXoQO2Y3eKfYkBe/um7XUu2SlrnXMHT7tqT+KvcEUWXnJvLgN7/jpJp8ZOFvHiB6w8OFjPob7VSzQbyultpkFvBGZR7Z6j8m24IoqAPj2OhZDPQ4W8kza4eu/LP2560MfcbJqblOG0tcVF72fQZ2fXKPVRyWv53pDLfxC38+jxdd+49mSTRcl7sfyYvqvW4HVb4IHnwwt+m+1Y4zG7GFxnP+FuywgXmELO1skNCdCHxZ2zopZDtZiBA0vplEkWv18V2lF7SNnaN17SVQQc83yfZnwTQjbfKBWd0HU+4DKtO5ADGJmMCMRV0ceq+BnP141Q45CFDxbQ==

Private key:

How can I decrypt the string?

edited Nov 14 '18 at 14:46

James K Polk

30k116896

asked Nov 14 '18 at 6:28

shisushi

687

I was trying to decrypt the string by RSA 2048 private key, but the error below is occurred.

java.lang.RuntimeException: java.lang.reflect.InvocationTargetException

        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811)

     Caused by: java.lang.reflect.InvocationTargetException

        at java.lang.reflect.Method.invoke(Native Method)

        at java.lang.reflect.Method.invoke(Method.java:372)

        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1016)

        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811) 

     Caused by: javax.crypto.IllegalBlockSizeException: input must be under 256 bytes

        at com.android.org.conscrypt.OpenSSLCipherRSA.engineDoFinal(OpenSSLCipherRSA.java:245)

        at javax.crypto.Cipher.doFinal(Cipher.java:1340)

Here is my code:

private fun rsaDecrypt(key: String, plain: String): String {

    var privateKey = ""

    if (key.contains("-----BEGIN RSA PRIVATE KEY-----") || key.contains("-----END RSA PRIVATE KEY-----")) {

        privateKey = key.replace("-----BEGIN RSA PRIVATE KEY-----", "").replace("-----END RSA PRIVATE KEY-----", "")

    }



    val base64Key = Base64.decode(privateKey.toByteArray(Charsets.UTF_8), Base64.DEFAULT)

    val spec = PKCS8EncodedKeySpec(base64Key)

    val keyFactory = KeyFactory.getInstance("RSA", "BC")

    val rsaPrivateKey = keyFactory.generatePrivate(spec)



    val cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding")

    cipher.init(Cipher.DECRYPT_MODE, rsaPrivateKey)

    val decryptedBytes = cipher.doFinal(plain.toByteArray(Charsets.UTF_8))



    return Base64.encodeToString(decryptedBytes, Base64.DEFAULT)

}

Encrypted string:

fhTGWW3Zn/nnhXoQO2Y3eKfYkBe/um7XUu2SlrnXMHT7tqT+KvcEUWXnJvLgN7/jpJp8ZOFvHiB6w8OFjPob7VSzQbyultpkFvBGZR7Z6j8m24IoqAPj2OhZDPQ4W8kza4eu/LP2560MfcbJqblOG0tcVF72fQZ2fXKPVRyWv53pDLfxC38+jxdd+49mSTRcl7sfyYvqvW4HVb4IHnwwt+m+1Y4zG7GFxnP+FuywgXmELO1skNCdCHxZ2zopZDtZiBA0vplEkWv18V2lF7SNnaN17SVQQc83yfZnwTQjbfKBWd0HU+4DKtO5ADGJmMCMRV0ceq+BnP141Q45CFDxbQ==

Private key:

How can I decrypt the string?

android kotlin rsa

edited Nov 14 '18 at 14:46

James K Polk

30k116896

asked Nov 14 '18 at 6:28

shisushi

687

edited Nov 14 '18 at 14:46

James K Polk

30k116896

asked Nov 14 '18 at 6:28

shisushi

687

edited Nov 14 '18 at 14:46

James K Polk

30k116896

edited Nov 14 '18 at 14:46

James K Polk

30k116896

edited Nov 14 '18 at 14:46

James K Polk

30k116896

asked Nov 14 '18 at 6:28

shisushi

687

asked Nov 14 '18 at 6:28

shisushi

687

asked Nov 14 '18 at 6:28

shisushi

687

refer stackoverflow.com/questions/10007147/…

– sasikumar
Nov 14 '18 at 8:40

With PKCS1Padding adds 11 bytes of padding so a message of the key size will be to large by 11 bytes. See the above comment link.

– zaph
Nov 14 '18 at 8:47

I don't believe that exception is possible with the data you've supplied. First of all, the private is not in PKCS#8 format, so I don't see how your code could've gotten past the keyFactory.generatePrivate(spec) without throwing an exception at that point.

– James K Polk
Nov 14 '18 at 14:54

Well, I actually ran your an almost identical Java version of your code on an Android emulator and worked as is, which was very surprising.

– James K Polk
Nov 14 '18 at 17:55

add a comment |

refer stackoverflow.com/questions/10007147/…

– sasikumar
Nov 14 '18 at 8:40

With PKCS1Padding adds 11 bytes of padding so a message of the key size will be to large by 11 bytes. See the above comment link.

– zaph
Nov 14 '18 at 8:47

I don't believe that exception is possible with the data you've supplied. First of all, the private is not in PKCS#8 format, so I don't see how your code could've gotten past the keyFactory.generatePrivate(spec) without throwing an exception at that point.

– James K Polk
Nov 14 '18 at 14:54

Well, I actually ran your an almost identical Java version of your code on an Android emulator and worked as is, which was very surprising.

– James K Polk
Nov 14 '18 at 17:55

refer stackoverflow.com/questions/10007147/…

– sasikumar
Nov 14 '18 at 8:40

With PKCS1Padding adds 11 bytes of padding so a message of the key size will be to large by 11 bytes. See the above comment link.

– zaph
Nov 14 '18 at 8:47

I don't believe that exception is possible with the data you've supplied. First of all, the private is not in PKCS#8 format, so I don't see how your code could've gotten past the keyFactory.generatePrivate(spec) without throwing an exception at that point.

– James K Polk
Nov 14 '18 at 14:54

Well, I actually ran your an almost identical Java version of your code on an Android emulator and worked as is, which was very surprising.

– James K Polk
Nov 14 '18 at 17:55

add a comment |

1 Answer
1

active

oldest

votes

The problem was very simple. You failed to base64-decode the plain argument. As an interesting aside, the Bouncycastle provider is somewhat forgiving in its PKCS8EncodedKeySpec generator. If the data passed is not PKCS8 then it attempts to parse it as a PKCS #1 RSA Private key, and only if that fails does it finally throw an exception. You private key is formatting according to PKCS#1, not PKCS#8.

answered Nov 14 '18 at 22:22

James K Polk

30k116896

add a comment |

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answered Nov 14 '18 at 22:22

James K Polk

30k116896

add a comment |

answered Nov 14 '18 at 22:22

James K Polk

30k116896

add a comment |

answered Nov 14 '18 at 22:22

James K Polk

30k116896

answered Nov 14 '18 at 22:22

James K Polk

30k116896

answered Nov 14 '18 at 22:22

James K Polk

30k116896

answered Nov 14 '18 at 22:22

James K Polk

30k116896

answered Nov 14 '18 at 22:22

James K Polk

30k116896

add a comment |

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