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1
49 package com.lowagie.text.pdf;
50
51 import com.lowagie.text.pdf.crypto.AESCipher;
52 import com.lowagie.text.pdf.crypto.ARCFOUREncryption;
53
54 public class StandardDecryption {
55 protected ARCFOUREncryption arcfour;
56 protected AESCipher cipher;
57 private byte[] key;
58 private static final int AES_128 = 4;
59 private boolean aes;
60 private boolean initiated;
61 private byte[] iv = new byte[16];
62 private int ivptr;
63
64
65 public StandardDecryption(byte key[], int off, int len, int revision) {
66 aes = revision == AES_128;
67 if (aes) {
68 this.key = new byte[len];
69 System.arraycopy(key, off, this.key, 0, len);
70 }
71 else {
72 arcfour = new ARCFOUREncryption();
73 arcfour.prepareARCFOURKey(key, off, len);
74 }
75 }
76
77 public byte[] update(byte[] b, int off, int len) {
78 if (aes) {
79 if (initiated)
80 return cipher.update(b, off, len);
81 else {
82 int left = Math.min(iv.length - ivptr, len);
83 System.arraycopy(b, off, iv, ivptr, left);
84 off += left;
85 len -= left;
86 ivptr += left;
87 if (ivptr == iv.length) {
88 cipher = new AESCipher(false, key, iv);
89 initiated = true;
90 if (len > 0)
91 return cipher.update(b, off, len);
92 }
93 return null;
94 }
95 }
96 else {
97 byte[] b2 = new byte[len];
98 arcfour.encryptARCFOUR(b, off, len, b2, 0);
99 return b2;
100 }
101 }
102
103 public byte[] finish() {
104 if (aes) {
105 return cipher.doFinal();
106 }
107 else
108 return null;
109 }
110 } |
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