TOPIC:

Encryption and Decryption 10 years 10 months ago #7007

manderin87
Topic Author
Offline
Junior Member
Posts: 21
Thank you received: 1

I am attempting to encrypt a pdf and then display it in the reader.

I am overriding the PDFAESStream class and attempting to input my own decryption method, but it is not working.

MessageDigest sha = MessageDigest.getInstance("SHA-1");
key = sha.digest(key);
key = Arrays.copyOf(key, 16);
SecretKeySpec skey = new SecretKeySpec(key, "AES");  
byte[] ivbytes = new byte[] { 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 };
IvParameterSpec iv = new IvParameterSpec(ivbytes);//need IV in CBC mode
m_dec_cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
m_dec_cipher.init(Cipher.DECRYPT_MODE, skey, iv);
m_enc_cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
m_enc_cipher.init(Cipher.ENCRYPT_MODE, skey, iv);

This does not work and I get a -3 error when opening the stream.

I am using the Secure.getString(context().getContentResolver(),Secure.ANDROID_ID).getBytes(UTF8) method to generate the 16 byte key after encoding it to SHA-1 and pulling out the first 16 bytes.

Can this work? What is wrong with the encryption?
thanks

Please Log in or Create an account to join the conversation.

Last edit: by jstampe.

Encryption and Decryption 10 years 10 months ago #7052

manderin87 Topic Author Offline Junior Member Posts: 21 Thank you received: 1	Any ideas? thanks
	Please Log in or Create an account to join the conversation.

Encryption and Decryption 10 years 10 months ago #7059

radaee Offline Moderator Posts: 1123 Thank you received: 73	there are simple codes in PDFTestAct //byte key[] = new byte[16]; //stream.open("/sdcard/ttt.pdf", key);//pdf file to encrypt. //stream.ImportFromFile("/sdcard/test.pdf");//import test.pdf and encrypt to ttt.pdf //stream.ExportToFile("/sdcard/test1.pdf");//decrypt to test1.pdf //stream.close();
	Please Log in or Create an account to join the conversation.

Encryption and Decryption 10 years 10 months ago #7064

manderin87 Topic Author Offline Junior Member Posts: 21 Thank you received: 1	Is it possible to encrypt outside the library and decrypt when opening the pdf?
	Please Log in or Create an account to join the conversation.

Encryption and Decryption 10 years 10 months ago #7065

nermeen Offline Platinum Member Posts: 962 Thank you received: 87	yes, as long as it was done using java methods
	Please Log in or Create an account to join the conversation.

Page:
1

Forum

Developing applications

Android development

Encryption and Decryption