Error :

Timestamp signature property generation error:  Unsupported transport protocol

Write url tsa server with http://

PROBLEM :
I am using rsa key to encrypt a long string. But it throws an exception like
javax.crypto.IllegalBlockSizeException: Data must not be longer than 245 bytes
at com.sun.crypto.provider.RSACipher.doFinal(RSACipher.java:344)
at com.sun.crypto.provider.RSACipher.engineDoFinal(RSACipher.java:389)
at javax.crypto.Cipher.doFinal(Cipher.java:2164)

CAUSE :

Using RSA to encrypt a large file is not a good idea. You could for example generate a random AES key, encrypt it using RSA and store it in the output file, and then encrypt the file itself with AES, which is much faster and doesn't have any problem with large inputs. The decryption would read the encrypted AES key, decrypt it, and then decrypt the rest of the file with AES.

" The RSA algorithm can only encrypt data that has a maximum byte length of the RSA key length in bits divided with eight minus eleven padding bytes, i.e. number of maximum bytes = key length in bits / 8 - 11 "

SOLVE

if key length 2048 maximum bytes data is 245 bytes
if key length 1024 maximum bytes data is 117 bytes

For Example :

p value is 47
q value is 71
public key value is 79
Message : "HARI INI"

Question :
How Is Encryption And Decryption Process ?

Answer :

MANUAL RSA ENCRYPTION PROCESS

Prime 1 (p) value :47
Prima 2 (q) value :71
public (e) key :79
N (p x q) value :3337
phi (N) --> (p-1) x (q-1) :3220
Private Key (d) : (1+k*3220)/79; k=1,2,3,....
find d with rounded results by trying k values
obtained private key value (d) :1019
So :
Public Key : (79,3220)
Private Key: (1019,3220)

Message (M) = HARI INI

===============
ENCRYPTION PROCESS
===============

Convert Message to Decimal Format
H = 72
A = 65
R = 82
I = 73
  = 32
I = 73
N = 78
I = 73

For this encryption process, I break m into smaller blocks, for example m is broken into six blocks that require 3 digits

M0=726
M1=582
M2=733
M3=273
M4=787
M5=003

CipherText (C) = Plaintext (M) ^ e mod N

C0 = 726 ^ 79 mod 3337 = 215
C1 = 582 ^ 79 mod 3337 = 776
C2 = 733 ^ 79 mod 3337 = 1743
C3 = 273 ^ 79 mod 3337 = 933
C4 = 787 ^ 79 mod 3337 = 1731
C5 = 3 ^ 79 mod 3337 = 158

CipherText: 215.776.1743.933.1731.158

Plaintext (M) =Ciphertext (C) ^ d mod N

P0 = 215 ^ 1019 mod 3337 = 726
P1 = 776 ^ 1019 mod 3337 = 582
P2 = 1743 ^ 1019 mod 3337 = 733
P3 = 933 ^ 1019 mod 3337 = 273
P4 = 1731 ^ 1019 mod 3337 = 787
P5 = 158 ^ 1019 mod 3337 = 3

Convert Desimal to Ascii
Return Decryption
72=H
65=A
82=R
73=I
32=
73=I
78=N
73=I

---- FINISH----

Berikut Kumpulan Paper atau Jurnal Terkait Kriptografi dan Steganografi

Algoritma AES

1. IMPLEMENTASI KRIPTOGRAFI PENGAMANAN DATAPADA PESAN TEKS, ISI FILE DOKUMEN, DAN FILE DOKUMENMENGGUNAKAN ALGORITMA ADVANCED ENCRYPTIONSTANDARD
2. Kriptografi Advanced Encryption Standard (AES)Untuk Penyandian File Dokumen
3. IMPLEMENTASI METODE ADVANCEDENCRYPTION STANDARD (AES) DANMESSAGE DIGEST 5 (MD5) PADA ENKRIPSIDOKUMEN(STUDI KASUS LPSE UNIB)
4. IMPLEMENTASI ALGORITMA ADVANCED ENCRYPTION STANDARD (AES)UNTUK ENKRIPSI DAN DEKRIPSI PADA DOKUMEN TEKS 
5. Implementasi Algoritma Advanced Encryption Standard (AES)128 Untuk Enkripsi dan Dekripsi File Dokumen
6. KRIPTOGRAFI ALGORITMA DES, AES/RIJNDAEL,BLOWFISH UNTUK KEAMANAN CITRA DIGITAL DENGANMENGGUNAKAN METODE DISCRETE WAVELETTRANSFORMATION (DWT)
7. PERBANDINGAN DAN ANALISIS PERFORMANSI ENKRIPSI-DEKRIPSI TEKSMENGGUNAKAN ALGORITMA AES DAN AES YANGTERMODIFIKASI BERBASISANDROID
8. Pembuatan Aplikasi Enkripsi Menggunakan AES dan RSA
9. PENERAPAN ENKRIPSI DAN DEKRIPSI FILEMENGGUNAKAN ALGORITMAADVANCED ENCRYPTION STANDARD (AES)
10. IMPLEMENTASI KRIPTOGRAFI MENGGUNAKAN ALGORITMAADVANCED ENCRYPTION STANDARD (AES) DENGAN METODE CBC(CHIPER BLOCK CHAINING) DAN PENGECEKAN ERROR DETECTIONCYCLIC REDUNDANCY CHECK
11. PERBANDINGAN ALGORITMA AES DENGANALGORITMA XTS-AES UNTUK ENKRIPSI DANDEKRIPSI TEKS SMS BERBASIS JAVA ME
12. PENGAMANAN DATA DENGAN MENGGUNAKANALGORITMA KRIPTOGRAFI AES, RC4 DAN KOMPRESI LZ77BERBASIS JAVA PADA BADAN KARANTINA PERTANIAN
13. Implementasi Kriptografi Algoritma AESSerta Algoritma Kompresi Huffman DenganMenggunakan Pemograman PHP

Kompresi ShannonFano

Sertifikat Elektronik lagi menjadi topik hangat akhir akhir ini terutama di Instansi Pemerintah. Contohnya bisa dibaca di artikel "Lemsaneg Luncurkan Sertifikasi Digital untuk Amankan Informasi Pemerintah" .
Sebenarnya apa sih sertifikat digital atau sertifikat elektronik itu?. Mari kita bahas satu per satu.
Kalau berdasarkan literatur yang saya dapatkan dari UU ITE No 11 Tahun 2008

Sertifikat  Elektronik  adalah  sertifikat  yang  bersifat  elektronik  yang  memuat  Tanda  Tangan Elektronik  dan  identitas  yang  menunjukkan  status  subjek  hukum  para  pihak  dalam  Transaksi Elektronik yang dikeluarkan oleh Penyelenggara Sertifikasi Elektronik. 

Sudah jelaskah dengan definisi diatas? Buat orang awam saya kira masih bingung dengan definisi diatas. Secara fisik, sertifikat digital hanyalah sebuah file. Saya tunjukan bentuk fisik sertifikat elektronik, temen temen bisa buka https://ib.bankmandiri.co.id/retail/Login.do?action=form.

 

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-----END CERTIFICATE-----