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Converting Secret Keys to and from Byte Arrays
This section provides a quick introduction of the SecretKeySpec class and the KeySpec interface. They can be used to convert secret keys into byte arrays to store them in external files.
2020-11-23, 10793👍, 5💬

💬 2020-11-23 rt: 12 234 45 5656

💬 2019-04-22 xyz: $9$RTHhSlWL7VsguO7dbw4oiHqf6CuOIRhyl K4JGDq.TQF/OIcyeLXNbsPTz3CAW8X

💬 2018-10-20 Herong: Marco, I just did a Google translation on your comment: "I wonder what all this could be". Are you trying to ask a question?

💬 2018-10-16 Marco: mi chiedo che cosa potrebbe essere tutto questo

💬 2015-11-03 cpp: hello

Illustration of RSA Algorithm: p,q=5,7
This section provides a tutorial example to illustrate how RSA public key encryption algorithm works with 2 small prime numbers 5 and 7.
2020-11-22, 2472👍, 4💬

💬 2020-11-22 Herong: fab, as shown in the tutorial, the modulus is 35. The encryption key (public key) is 5, and the decryption key (private key) is ...

💬 2020-11-15 fab: Construct an example of the RSA scheme as follows. The two primes to be used for the modulus N are 5 and 7. What is (N)? Confir...

💬 2019-01-21 Herong: someone, why 35 and 5 must be coprime numbers?

💬 2019-01-16 someone: >Compute n = p*q: n = 5*7 = 35 >Compute m = (p-1)*(q-1): m = 4*6 = 24 >Select e, such that e and m are coprime numbers: e = 5 35...

DES Algorithm Java Implementation
This chapter provides tutorial examples and notes about DES algorithm implementation in Java language. Topics include an example Java implementation of DES encryption and decryption algorithm; test cases of single block cleartext and ciphertext.
2020-11-11, 7051👍, 17💬

💬 2018-12-13 syed zia ur rehman: i realy like your link

💬 2017-10-15 Herong: CipherDES.java also works as a decryption program. Try it by running "java DesCipher decrypt keyFile input output".

💬 2017-10-09 aa: thanks, but where i can find DES decryption

💬 2017-10-09 Denys: thx

💬 2017-04-23 aa: thanks

(More comments ...)

EC Private and Public Key Pair
This section introduces what is EC (Elliptic Curve) key pair - a pair of private key and public key constructed from a given subgroup generator in a given elliptic curve group.
2020-11-07, 113👍, 1💬

💬 2020-11-07 abc: Ravana

What Is PKCS5Padding?
This section describes what is PKCS5Padding - a schema to pad cleartext to be multiples of 8-byte blocks.
2020-11-04, 28457👍, 9💬

💬 2020-11-04 perico: otra vez va a salir trump??

💬 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...

(More comments ...)

What is ECB (Electronic CodeBook) Operation Mode?
This section describes what is ECB (Electronic CodeBook) Operation Mode - each plaintext block is encrypted independently without any input from other blocks.
2020-10-18, 3577👍, 4💬

💬 2020-10-18 Herong: donjo, there is no real applications that use the ECB mode.

💬 2020-10-16 donjo dumdum: What is application of ECB mode operation

💬 2016-01-10 Todd: Thanks!

Geometric Introduction to Elliptic Curves
This chapter provides a geometric introduction of elliptic curves and the associated addition operation. Topics includes what is an elliptic curve and its geometric properties; geometric algorithm defining an addition operation; infinity point or identity element; commutativity and associativity of ...
2020-09-12, 166👍, 1💬

💬 2020-09-12 NA: NA

"OpenSSL" Generating Certificates in DER and PEM
This section provides a tutorial example on how to generate certificates in DER and PEM formats using 'OpenSSL'.
2020-09-09, 726👍, 2💬

💬 2020-09-09 test: test

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.
2020-07-02, 342👍, 2💬

💬 2020-07-02 Koshal Pravin jangale: Nice

About This Book: EC Cryptography Tutorials
This section provides some detailed information about this book - EC Cryptography Tutorials - Herong's Tutorial Examples.
2020-06-23, 132👍, 1💬

💬 2020-06-23 chris: Thank so much ! All Crypto printed books in cart !! Very well done. Most useful books i've seen in quite some time.

EC Cryptography Tutorials - Herong's Tutorial Examples
This EC (Elliptic Curve) cryptography tutorial book is a collection of notes and sample codes written by the author while he was learning cryptography technologies himself. Topics include rule of chord and point addition on elliptic curves; Abelian groups with additive and multiplicative notations; ...
2020-06-23, 1610👍, 4💬

💬 2020-06-23 Herong: Chris, contact me by email. I will send you a PDF copy. Thanks for your comment.

💬 2020-06-22 chris: Sorry for fuss. Bought this ebook on google. bad idea. Should have not done that and just got the physical book or maybe ebook o...

💬 2019-07-02 Eleftheria Drosopoulou: Hello Herong, Nice blog! I am editor at Java Code Geeks (www.javacodegeeks.com). We have the JCG program (see www.javacodegeeks....

💬 2019-01-01 Yale: Thank you!

Illustration of DSA Algorithm: p,q=23,11
This section provides a tutorial example to illustrate how DSA digital signature algorithm works with small prime modulus p=23 and prime divisor q=11.
2020-06-22, 602👍, 4💬

💬 2020-06-22 Filip: Very helpful, thanks!

💬 2020-02-24 Herong: Sanjay, hash value of 3 was used as a simple example, not calculated.

💬 2020-02-18 Sanjay: How hash value h =3 ? how you calxulate

Introduction of DSA (Digital Signature Algorithm)
This chapter provides tutorial notes and example codes on DSA (Digital Signature Algorithm). Topics include introduction of DSA; illustration of DSA key generation, message signing and signature verification; proof of Digital Signature Algorithm.
2020-06-04, 3981👍, 12💬

💬 2020-06-04 ben: How are you?

💬 2018-04-07 Digital Signature Algorithm: Conclusions: DSA (Digital Signature Algorithm) uses public key and private key to generate and verify digital signatures. DSA pu...

💬 2018-04-07 Submit Your Comment: Please write meaningful comments. Thanks! ☺

💬 2018-04-07 world: hello

💬 2018-02-20 amit: hello

(More comments ...)

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.
2020-06-01, 13334👍, 5💬

💬 2018-10-29 Thanks!: meaningful comments.

💬 2017-03-15 noname: thanks

💬 2016-01-25 Dev: hello

DES Decryption Algorithm
This section describes DES decryption algorithm - identical to the encryption algorithm step by step in the same order, only with the subkeys applied in the reverse order.
2020-05-19, 3644👍, 4💬

💬 2020-05-19 Nick: test comment

💬 2019-06-17 bIPFaV0PLbO9qrDgn+p43A==: bIPFaV0PLbO9qrDgn+p43A==

💬 2017-12-16 Herong: deepak, is this a encrypted comment?

💬 2017-12-11 deepak: 9bc94bbaf6d380eb8f8c6548b2cf6343ccef 5978768e3d69b796d6ef0839172b

Cleartext Block Size for RSA Encryption
This section discusses what is the most efficient block size when dividing a Cleartext message into blocks for RSA public encryption. The suggested block size is 'floor((x-1)/8)', where 'x' is the RSA key size, or the key modulus bit length.
2020-03-13, 137👍, 1💬

Certificate in PEM Format
This section describes what is certificate PEM (Privacy Enhanced Mail) format - A format uses PEM idea to convert a certificate in DER format to a message of printable characters. The conversion uses the Base64 encoding.
2020-02-23, 5917👍, 4💬

💬 2020-02-23 Herong: Mark, if your certificate is signed by your own CA, put it on the Apache server together with the CA certificate to test. Other ...

💬 2020-02-17 mark scorfield: Hi i have a pem certificate x509 that i would like to share against my own certificate signing authority , what is the best way ...

💬 2016-03-30 Herong: Bcbin, why don't you post your question here? Maybe others can help you too. Or send me an email directly.

💬 2016-03-27 bcbin: my name is bcbin, my email is bcbin@yahoo.com. please connecting me. i need you help ):

What Is a Digital Signature?
This section describes what is a digital signature and what is the process of generating and verifying digital signature from a message.
2020-02-23, 3285👍, 4💬

💬 2020-02-23 Herong: Sanjay, you are welcome!

💬 2020-02-17 Sanjay: Thank u so much

💬 2019-01-29 nilo: Hola

💬 2016-04-26 santosh patil: Its easy to understand

DESSubkeysTest.java - DES Key Schedule Algorithm Illustration
This section provides a tutorial Java program, DESSubkeysTest.java, to illustrate how DES key schedule algorithm works.
2020-02-10, 1014👍, 3💬

💬 2020-02-10 Art: No comments

💬 2018-07-20 aqil: havr fun

mcrypt Library for PHP
This section describes the mcrypt library - encryption extension for PHP. mcrypt supports DES and many other encryption algorithms.
2019-12-19, 114👍, 1💬

Blowfish - 8-Byte Block Cipher
This chapter provides tutorial examples and notes about Blowfish block cipher. Topics include Blowfish encryption and decryption algorithm; Blowfish sub-key generation schema, Blowfish algorithm implementation in Java.
2019-12-16, 282👍, 1💬

💬 2019-12-16 gio: i love you

What Is DSA (Digital Signature Algorithm)?
This section describes the DSA (Digital Signature Algorithm) algorithm, which consists of 2 parts: generation of a pair of public key and private key; generation and verification of digital signature.
2019-10-22, 30311👍, 17💬

💬 2018-08-29 Shawn: Thanks for the detailed explanation.

💬 2017-10-29 Abi: Very informative

💬 2017-04-01 Herong: T, A double asterisk ** is the exponentiation operation that raise a base to a power.

💬 2017-03-27 t: What is "**"?

💬 2017-03-10 appalaraju: useful

(More comments ...)

"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.
2019-10-05, 43269👍, 7💬

💬 2019-10-05 Herong: Fatin, what are you getting from the output?

💬 2019-09-27 Fatin: Please help me, i cannot get it that way

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

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

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

(More comments ...)

Testing RsaKeyEncryption.java with a 16-bit Key
This section provides a tutorial example on testing my RSA encryption and decryption implementation using the java.math.BigInteger class with a 16-bit key.
2019-09-02, 107👍, 1💬

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