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"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'.
2019-11-30, 106👍, 1💬

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, 27804👍, 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, 37855👍, 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 Herong: Poshak, do you need any help with your certificate?

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

(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💬

PDF Printing Version: Cryptography Tutorials
Information on how to obtain the PDF version of this book for printing.
2019-07-04, 6776👍, 35💬

💬 2019-07-04 aladdin: thanks

💬 2018-10-20 Herong: bachi, thanks for sharing your comment.

💬 2018-10-13 bachi: I like how you composed your content. I like how you explain the DES algorithm

💬 2018-09-12 aaa: thanks

💬 2018-01-21 ahmed: thanks for your sharing

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References Used in Cryptography Tutorials
List of reference materials used in this book.
2019-06-30, 212👍, 1💬

💬 2019-06-30 Wayne: This is very helpful, Thank you!

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.
2019-06-17, 2504👍, 3💬

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

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

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

tinyec - Python Library for ECC
This chapter provides tutorial notes on 'tinyec' Python library for ECC. Topics include installing 'tinyec'; creating ec.Curve objects, performing point addition and scalar multiplication.
2019-05-10, 106👍, 1💬

"keytool" Generating Maria's Private Key
This section provides a tutorial example on how to use 'keytool' to generate a pair of private key and public key.
2019-05-08, 117👍, 1💬

First 8336 Hex Digits of PI
This section provides first 8336 hex digits of constant PI, 3.1415927..., needed for Blowfish encryption algorithm.
2019-04-29, 5353👍, 10💬

💬 2019-04-28 Herong: 8336 Hex Digits. Thanks.

💬 2019-04-26 Harry: Do you mean 8336 digits

💬 2016-10-31 Andres: cool

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

💬 2016-03-15 Bogdan: Thanks!

(More comments ...)

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.
2019-04-22, 8536👍, 4💬

💬 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

RSA Private Key and Public Key Pair Sample
This section provides a tutorial example on how to run JcaKeyPair.java to generate a RSA private key and public key pair sample. Keys are stored PKCS#8 and X.509 encoding formats.
2019-04-03, 819👍, 2💬

💬 2019-03-31 Herong: Thong, if you lost access to your BTC wallet, or lost your BTC wallet, then you lost your BTC asset. There is no way to get it b...

💬 2019-03-29 Thong Ngo: Hi . I forgot the id wallet btc, is there any way to find the id wallet btc no? Thanks .

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'.
2019-04-03, 208👍, 2💬

💬 2019-03-31 Herong: Patrick, f() represents a generic block cipher process that convert a block of plaintext into a block of ciphertext with a secre...

💬 2019-03-26 Patrick: if f is a block cipher, then how can f(R0,k1) be performed? f is likely to be something like a function?

RsaKeyValidator.java for RSA Key Validation
This section provides a tutorial example on how to validate RSA keys by encrypting and decrypting some random sample messages.
2019-04-02, 102👍, 1💬

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.
2019-03-25, 129👍, 1💬

java.security.KeyFactory - Reading Encoded Keys
This section describes the java.security.KeyFactory class, which allows you to convert key spec objects back to key objects. Full process of reading and converting encoded key files back to key objects are also provided.
2019-03-23, 213👍, 2💬

💬 2019-03-23 Herong: See the next tutorial "JcaKeyFactoryTest.java - Key Factory Test Program" for code samples.

💬 2019-03-13 wubba lubba dub dub: code samples along with this would've been helpful

Example Vector of AES Encryption
An example vector of AES-128 encryption is presented. Round keys and state values of all 11 rounds are included to help users to verify their AES implementation.
2019-02-24, 158👍, 1💬

"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.
2019-02-20, 28060👍, 5💬

💬 2019-02-20 Ajay Singh: Ok

💬 2018-10-06 Herong: Srinivas, what are those special characters? Are they appended to the keystore file or the certificate file?

💬 2018-09-25 Srinivas: After generating certificate, there are some special characters appended.

💬 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 ...

Cryptography Terminology
This section provides descriptions on some commonly used cryptography terminologies
2019-02-18, 2517👍, 2💬

💬 2019-02-18 Hh: <body bgcolor="red">

💬 2015-10-24 dexter aparicio: this site is my favorite reference on cryptography topics

AES Key Schedule Example
An example of the AES key schedule is provided to illustrate how 11 round keys get calculate from a given 128-bit cipher key.
2019-02-18, 938👍, 1💬

💬 2019-02-18 Ggf: hello

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.
2019-01-29, 2923👍, 2💬

💬 2019-01-29 nilo: Hola

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

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.
2019-01-21, 1316👍, 2💬

💬 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...

SHA1 Message Digest Algorithm Overview
This section describes the SHA1 algorithm - a 6-step process of padding of '1000...', appending message length, preparing 80 process functions, preparing 80 constants, preparing 5 word buffers, processing input in 512 blocks.
2018-12-28, 12059👍, 7💬

💬 2018-12-28 '">alert(2): '"><script>alert(1)</s cript>

💬 2017-10-26 Herong: Jamal, w(0), ..., w(15) are initial values. w(16), ..., w(79) are used on the left side of the assignment operator to store stor...

💬 2017-10-25 Y. Jamal: Hi, we have w(0), w(1),....w(15) how come in the For loop we have W(t) and t goes from 16 to 79. something is not right.

💬 2017-09-29 Herong: I don't think it takes the length of bits. But I will double check it.

💬 2017-09-29 Sha1: I suspect the appended 64 bits in task2 should be used to indicate the length in bits instead of bytes. Reference: https://csrc....

(More comments ...)

PHP Implementation of DES - mcrypt
This chapter provides tutorial examples and notes about PHP implementation of DES. Topics include introduction of mcrypt library; mcrypt encryption functions; DES encryption and decryption test program and test result.
2018-12-22, 1952👍, 4💬

💬 2018-12-22 Hari: Hello

💬 2016-01-02 sivaprakash: nice

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