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MD5 Mesasge Digest Algorithm
This chapter provides tutorial notes and example codes on the MD5 message digest algorithm. Topics include MD5 algorithm overview; using MD5 in Java, PHP, and Perl.
2017-09-10, 701👍, 2💬

💬 2016-05-19 ishvar: hello ahemad

Using Certificates in Firefox
This chapter provides tutorial notes and example codes on using certificates in Firefox 18. Topics include why Web browsers need certificates; viewing the certificate from an https Web server; exporting a certificate from Firefox 18 to a certificate file; importing a CA certificate into Firefox 18.
2017-08-31, 1440👍, 1💬

💬 2017-08-31 bobby: ok will do

Cryptography Tutorials - Herong's Tutorial Examples
This cryptography tutorial book is a collection of notes and sample codes written by the author while he was learning cryptography technologies himself. Topics include AES, blowfish, certificate, cipher, decryption, DES, digest, encryption, keytool, MD5, OpenSSL, PEM, PKCS#8, PKCS#12, private key, p...
2017-08-05, 21012👍, 4💬

💬 2017-06-17 Herong: Neil, I will try my best. Thanks for the comment.

💬 2017-06-14 Neil Shrestha-Birtch: It helped me! thanks for keeping this resource up.

💬 2016-01-11 Sandy: Good job Dr Herong Yang!

💬 2015-11-07 Herong: My Facebook Like count is not going up. ☹ Maybe there is not that many active Facebook users out there as we thought...

mcrypt DES Encryption Testing Program
This section provides a tutorial example on how to use the DES algorithm in a specific operation mode as block or stream cipher.
2017-08-03, 708👍, 3💬

💬 2017-08-03 Herong: Deepan, Which part is difficult for you to understand?

💬 2017-07-27 Deepan: I can't understand

"OpenSSL" Viewing Certificates in DER and PEM
This section provides a tutorial example on how to use 'OpenSSL' to view certificates in DER and PEM formats generated by the 'keytool -exportcert' command.
2017-05-27, 30906👍, 5💬

💬 2017-05-27 Herong: Yes, asn1parse is a nice tool. I will add some examples later.

💬 2017-05-23 Herong: Poshak, do you need any help with your certificate?

💬 2017-05-23 Derek Callaway: openssl asn1parse is also useful for displaying certificate contents...

💬 2017-05-23 poshak: MIIC8DCCAIGgAwIBAgIJAM/+E5HIKoWGMAoG ...

💬 2015-09-23 Rohan: Very helpful. Thanks :)

Visiting a "https" Web Site with Chrome
This section describes how Google Chrome 24 shows a lock icon when you visit an 'https' Web site to provide you more security related information.
2017-05-10, 277👍, 1💬

What Is DER (Distinguished Encoding Rules) Encoding?
This section describes the DER (Distinguished Encoding Rules) - A binary format of encoding a data value of any data types including nested data structures.
2017-03-30, 6978👍, 3💬

💬 2017-03-15 noname: thanks

💬 2016-01-25 Dev: hello

DsaSignatureGenerator.java - Generating DSA Digital Signature
This section provides tutorial example on how to generate a digital signature for a message file with a DSA private key using the SHA1withDSA algorithm.
2017-03-13, 3368👍, 5💬

💬 2017-03-13 dingdong: heheheheehhe

💬 2016-10-15 Herong: Akash, can you check to ensure your key is a DSA key?

💬 2016-10-14 Akash: Exception occurs as follows: java.security.spec.InvalidKeySpecExc eption:Inappropriate key specification what it means? can you ...

What Is Cryptography?
This section describes what is cryptography - The study of techniques related to all aspects of data security.
2017-02-18, 2223👍, 5💬

💬 2017-02-18 gabu: ggoodd

💬 2016-11-17 mohamed: yes

💬 2015-10-20 Herong: Hi Ian, the Rail Fence cipher is very simple example of encryption we can do manually. See the Transposition cipher page at wiki...

💬 2015-10-19 Ian T. Lee: Can you give me a simple example of how to do cryptography manually?

💬 2015-08-06 arnav: good

CipherDES.java - A Java Implementation of DES
This section provides a tutorial Java program, CipherDES.java - A Java Implementation of DES encryption and decryption algorithm.
2017-02-16, 9510👍, 9💬

💬 2017-02-16 Herong: Andro, I think implementation of DES using String methods will be slower than using byte and int operations.

💬 2017-02-12 Andro: Good done. I have created my own DES with benefits of string methods in Java. My DES receives binary string and key, then cipher...

💬 2016-03-03 Dede: Helps a lot, currently developping a mobile application that has to do with encryption. Thanks

💬 2015-10-16 Herong: Skip, Good luck on your study!

💬 2015-10-15 Skip: I'm taking a graduate course in cryptography and this was extremely helpful for going from DES visual to DES in java. I really a...

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Viewing Certificate Path
This section provides a tutorial example on how to view certificate path when visiting an 'https' Web site in IE 9. The top certificate in a certificate path is the CA certificate, which is trusted automatically.
2017-01-31, 546👍, 1💬

💬 2017-01-31 kishor: -----BEGIN CERTIFICATE----- MIIDqjCCApICCQC6MOh9nHUvUjANBgkqhkiG 9w0BAQUFADCBljELMAkGA1UEBhMCVVMxETAPBgNVBAgTCENvbG9yYWRvMRMwEQY. ..

Using MD5 Message Digest in Java
This section provides a tutorial example on how to use MD5 message digest algorithm in Java. The JDK JCE package offers the MD5 algorithm through a generic message digest class, javax.security.MessageDigest.
2017-01-27, 137👍, 2💬

What is CFB (Cipher FeedBack) Operation Mode?
This section describes what is CFB (Cipher FeedBack) Operation Mode - each plaintext block is XORed with the encrypted version of the ciphertext of the previous block to be the ciphertext block.
2017-01-13, 1641👍, 3💬

💬 2016-12-07 fakhrulislam: i want a copy of this book !

💬 2015-11-06 poonam: a perfect explanation

RsaKeyGenerator.java for RSA Key Generation
This section describes the initial draft of a RSA public key and private key generation implementation using the java.math.BigInteger class.
2017-01-05, 1493👍, 2💬

💬 2017-01-05 Herong: Alex, you are right. q should be selected independently from p. I will make a change in the next revision.

💬 2016-12-28 Alex T.: Using nextProbablePrime() to compute q appears somewhat risky to me: An attacker with the knowledge of N=p*q could simply comput...

MD5 Message Digest Algorithm Overview
This section describes the MD5 algorithm - a 5-step process of padding of '1000...', appending message length, dividing as 512-bit blocks, initializing 4 buffers, and 4-round of hashing each block.
2016-11-21, 6902👍, 6💬

💬 2016-11-21 this is a burner: concise and accurate, thanks

💬 2016-09-26 brijesh gupta: its helpful

💬 2016-06-17 Ampera: Makasih

RSA Public Key Encryption Algorithm
This section describes the RSA public key encryption algorithm. Generating public and private keys used in RSA encryption requires two large prime numbers.
2016-11-21, 120👍, 1💬

DES Encryption Operation Modes
This chapter provides tutorial examples and notes about DES encryption operation modes. Topics include how different blocks of plaintext can be coupled together to improve the strength of the DES encryption algorithm; ECB (Electronic CodeBook), CBC (Cipher Block Chaining), CFB (Cipher FeedBack), and...
2016-11-12, 394👍, 1💬

💬 2016-11-12 kazim: very good webpage

SHA1 Mesasge Digest Algorithm
This chapter provides tutorial notes and example codes on the SHA1 message digest algorithm. Topics include SHA1 algorithm overview; using SHA1 in Java, PHP, and Perl.
2016-11-05, 1426👍, 5💬

💬 2015-10-14 Herong: Yojana, information on key generation of Blowfish Algorithm can be found in Key Schedule (Sub-Keys Generation) Algorithm tutoria...

💬 2015-10-13 Yojana Yadav: Plz send me the detail of key generation of Blowfish Algorithm

💬 2013-06-28 Herong: Abbas, You are welcome!

💬 2013-06-26 abbas: thank you for sha-1 and it's so helpful

First 8336 Hex Digits of PI
This section provides first 8336 hex digits of constant PI, 3.1415927..., needed for Blowfish encryption algorithm.
2016-10-31, 4649👍, 8💬

💬 2016-10-31 Andres: cool

💬 2016-04-07 Tamas Losonczi: This is great

💬 2016-03-15 Bogdan: Thanks!

💬 2015-12-03 Herong: Sadi, we only need (18*32+4*256*32)/4=8336 hex digits for the Blowfish encryption algorithm. I have typos in my tutorials. I wil...

💬 2015-12-02 Sadi: Sorry, I meant "8336 and not 8366"... Also would you like to compare these with "http://hexpi.sourceforge.net/" as there are som...

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"keytool" Importing CA's Own Certificate
This section provides a tutorial example on how to import CA's certificate generated by 'OpenSSL' into a 'keystore' file using 'keytool'
2016-10-20, 489👍, 2💬

💬 2016-10-20 Herong: Akhtar, AES256 encryption does not require any certificates. It requires a secret AES key, see Introduction to AES (Advanced Enc...

💬 2016-10-19 Akhtar: I have also a certificate file (.cer) .I did the same procedure to import in to mykey store and got .jks file but, now i want to...

What Is Block Cipher?
This section describes what is block cipher - An encryption scheme in which 'the clear text is broken up into blocks of fixed length, and encrypted one block at a time'.
2016-09-26, 290👍, 1💬

💬 2016-09-26 eva: soooooooo Amazing thank so much this site helping to learn about blowfish algorthm more

Blowfish Cipher Algorithm
This section describes the Blowfish cipher algorithm - A 16-round Feistel cipher with block size of 64 bits developed by Bruce Schneier in 1993.
2016-08-03, 635👍, 2💬

💬 2016-08-03 azi: fantastic

"keytool" Exporting Certificates in DER and PEM
This section provides a tutorial example on how to export certificates in DER and PEM format using the 'keytool -exportcert' command.
2016-06-27, 18998👍, 2💬

💬 2016-06-27 Herong: Mandar, can you double check your command? The error indicates you entered a wrong password.

💬 2016-06-23 Mandar: converting to der is sucessful. while converting to pem, I am getting below error. keytool error: java.io.IOException: Keystore ...

What Is PKCS5Padding?
This section describes what is PKCS5Padding - a schema to pad cleartext to be multiples of 8-byte blocks.
2016-06-16, 15639👍, 8💬

💬 2016-06-16 yo: hola pescado

💬 2016-04-04 ankit: this is me.

💬 2016-01-28 John: Herong, thanks a lot.

💬 2016-01-27 Herong: John, the schema of PKCS7Padding can be described as below: Pad the input at the trailing end with k−(l mod k) octets with the s...

💬 2016-01-24 John: For PKCS7Padding, what is the schema? I'm interested to what is after 0x0909090909090909099

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