The IT security landscape is littered with events where cryptography was not properly used, leading to leaked sensitive data and major problems for organizations. Learn how to encrypt and hash data using cryptography features in PHP, including password hashing, libsodium, mcrypt, OpenSSL, CrackLib, and CSPRNG. Refresh on current industry standards and review cryptographic algorithms. Come ready to hash passwords, experiment with algorithm costs, and crack weak encryption using attacks from timing, brute force, and rainbow tables.

1. CRYPTOGRAPHY WITH PHP
MARK NIEBERGALL
ZendCon 2017 Workshop
https://joind.in/talk/7b305

2. CRYPTOGRAPHY WITH PHP
ABOUT MARK NIEBERGALL
▸ PHP since 2005
▸ Masters degree in MIS
▸ Senior Software Engineer
▸ Drug screening project
▸ UPHPU President
▸ SSCP, CSSLP Certified and SME
▸ Drones, fishing, skiing, father, husband

3. CRYPTOGRAPHY WITH PHP
ABOUT MARK NIEBERGALL

4. CRYPTOGRAPHY WITH PHP
ABOUT MARK NIEBERGALL

5. CRYPTOGRAPHY WITH PHP
ABOUT MARK NIEBERGALL

6. CRYPTOGRAPHY WITH PHP
OBJECTIVES
▸ Time on the keyboard
▸ Learn about and use PHP cryptography and hashing
libraries
▸ Security considerations with implementation

7. CRYPTOGRAPHY WITH PHP
OBJECTIVES
▸ Coding time!
▸ Various modules
▸ Estimated time (5, 10, or 15 minutes)
▸ Cryptography games will apply what was covered

8. CRYPTOGRAPHY WITH PHP
SCHEDULE
▸ 9:00-9:30 Setup and covering slides that including terminology and
cryptography
▸ 9:30-9:50 PHP hash, password hashing
▸ 9:50-10:00 Break, lock picking
▸ 10:00-10:50 CSPRNG, OpenSSL
▸ 10:50-11:00 Break, more lock picking
▸ 11:00-11:15 libsodium
▸ 11:15-11:55 Cryptography Games
▸ 11:55-12:00 Regroup and conclusion

9. CRYPTOGRAPHY WITH PHP
OVERVIEW
▸ Environment Setup
▸ Why Cryptography
▸ Definitions
▸ Role of Cryptography
▸ Algorithms
▸ Encryption with PHP
▸ Considerations
▸ Cryptography Games

10. CRYPTOGRAPHY WITH PHP
ENVIRONMENT SETUP

11. CRYPTOGRAPHY WITH PHP
ENVIRONMENT SETUP
▸ PHP 5.5+, best is 7.0+
▸ Ideally have libsodium PECL extension (see https://
paragonie.com/book/pecl-libsodium/read/00-
intro.md#installing-libsodium) or 7.2 (RC)
▸ Once you are up and running, please help others
▸ Worse case, use https://3v4l.org/

12. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY

13. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY

14. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY

15. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY

16. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY
▸ Over 100,000 incidents in 2016 with 3,141 confirmed
breaches
▸ Attacks largely for financial gain
▸ Many going after sensitive data

17. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY
▸ Review Verizon 2017 Data Breach Investigations Report
▸ Yearly report
▸ Cybersecurity investigations report
▸ Pulls from many sources
▸ Lots of informative charts

18. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY

19. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY
Incidents by industry

20. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY

21. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY

22. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY

23. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY

24. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY

25. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY
▸ No organization is immune
▸ Cryptography significantly reduces breach cost
▸ Cryptography can prevent leak of actual sensitive data

26. CRYPTOGRAPHY WITH PHP
WHY CRYPTOGRAPHY
▸ Attack Countermeasures
▸ Good password policy
▸ Encrypt sensitive data
▸ Encrypt computer disks and devices
▸ Keep current with patches

27. CRYPTOGRAPHY WITH PHP
DEFINITIONS

28. CRYPTOGRAPHY WITH PHP
DEFINITIONS
▸ Cryptography
▸ The process of writing or reading secret messages or
codes
▸ Classical cryptography started thousands of years ago
▸ Advanced during wars of 20th century
▸ The science or study of secret communications

29. CRYPTOGRAPHY WITH PHP
DEFINITIONS
▸ Encryption
▸ To change information from one form to another
especially to hide its meaning
▸ En: to make
▸ Crypto: secret or hidden
▸ The actual changing of a communication

30. CRYPTOGRAPHY WITH PHP
DEFINITIONS
▸ Algorithm
▸ A set of steps that are followed in order to solve a
mathematical problem or to complete a computer
process

31. CRYPTOGRAPHY WITH PHP
DEFINITIONS
▸ Cipher
▸ A way of changing a message to keep it secret
▸ An algorithm used to encrypt or decrypt
▸ Classically included substitution and transposition
▸ A becomes 1
▸ A becomes Z
▸ Abc123 becomes 123Abc
▸ Backwards

32. CRYPTOGRAPHY WITH PHP
DEFINITIONS
▸ Hash
▸ To chop into small pieces
▸ Maps data to a string
▸ One-way hash functions
▸ Schneier “workhorses of modern cryptography”
▸ Input is the message, output is the digest

33. CRYPTOGRAPHY WITH PHP
ROLE OF CRYPTOGRAPHY

34. CRYPTOGRAPHY WITH PHP
ROLE OF CRYPTOGRAPHY
▸ World War II
▸ Enigma Machine used by Nazi Germany
▸ Code breaking by Allies, including Alan Turing

35. CRYPTOGRAPHY WITH PHP
ROLE OF CRYPTOGRAPHY
▸ Secure communications from third parties
▸ Confidentiality of communications

36. CRYPTOGRAPHY WITH PHP
ROLE OF CRYPTOGRAPHY
▸ Secure data at rest
▸ Secure data in transit

37. CRYPTOGRAPHY WITH PHP
ROLE OF CRYPTOGRAPHY
▸ First 2 A’s in the AAA Framework
▸ Authentication: credentials
▸ Authorization: encrypt and decrypt data
▸ Accounting

38. CRYPTOGRAPHY WITH PHP
ALGORITHMS

39. CRYPTOGRAPHY WITH PHP
ALGORITHMS
▸ One Way Hash

40. CRYPTOGRAPHY WITH PHP
ALGORITHMS
▸ One Way Hash
▸ Data is hashed
▸ Cannot go backwards
▸ Integrity checks
▸ Password checks
▸ Identifiers; ex: Git and Mercurial

41. CRYPTOGRAPHY WITH PHP
ALGORITHMS
▸ One Way Hash
▸ MD5
▸ SHA-1, SHA-2, SHA-3

42. CRYPTOGRAPHY WITH PHP
ALGORITHMS
▸ Symmetric-Key

43. CRYPTOGRAPHY WITH PHP
ALGORITHMS
▸ Symmetric-Key
▸ Same key to encrypt and decrypt
▸ Shared secret key
▸ Susceptible to plaintext attacks (known and chosen) and
cryptanalysis (differential and linear)

44. CRYPTOGRAPHY WITH PHP
ALGORITHMS
▸ Symmetric-Key
▸ DES
▸ Triple DES
▸ AES

45. CRYPTOGRAPHY WITH PHP
ALGORITHMS
▸ Symmetric-Key
▸ Blowfish
▸ Twofish
▸ Threefish

46. CRYPTOGRAPHY WITH PHP
ALGORITHMS
▸ Asymmetric-Key

47. CRYPTOGRAPHY WITH PHP
ALGORITHMS
▸ Asymmetric-Key
▸ Heavily used in cryptography
▸ Public and private keys
▸ Public key is publicly available
▸ Private key is kept secret

48. CRYPTOGRAPHY WITH PHP
ALGORITHMS
▸ Asymmetric-Key

49. CRYPTOGRAPHY WITH PHP
ALGORITHMS
▸ Asymmetric-Key
▸ Public key used to authenticate messages from owner of
the private key
▸ Public key used to encrypt message to send to owner of
the private key
▸ Private key used to decrypt inbound messages
▸ Private key used to encrypt outbound messages

50. CRYPTOGRAPHY WITH PHP
ALGORITHMS
▸ Asymmetric-Key (Public-Key)
▸ RSA
▸ DSA

51. CRYPTOGRAPHY WITH PHP
ALGORITHMS
▸ Broken
▸ DES
▸ MD2, MD4, MD5
▸ SHA-1
▸ GOST
▸ Panama
▸ RC4

52. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

53. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ String functions just don’t cut it
▸ bin2hex
▸ strrev
▸ base64_encode
▸ dechex
▸ ord and chr (ASCII)
▸ str_replace

54. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ Hash
▸ Password hashing
▸ mcrypt
▸ CSPRNG
▸ openssl
▸ libsodium
▸ StupidPass

55. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ Hash
▸ hash_algos for array of options
▸ hash($algorithm, $message, $raw = false);
▸ hash_file for file contents hash
▸ hash_equals for comparing hashed values

56. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ Hash - Coding time!
▸ 5 minutes
▸ hash_algos for array of algorithms
▸ Output available algorithms
<?php
print_r(hash_algos());
▸ See https://en.wikipedia.org/wiki/
Comparison_of_cryptographic_hash_functions

57. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ Hash - Coding time!
▸ 10 minutes
▸ hash($algorithm, $message, $raw = false);
▸ foreach hash_algos generate hash
▸ Review output content, including characters, length
▸ Does different message or message length impact hash
length?

58. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ Hash - Coding time!
▸ 5 minutes
▸ hash_file for file contents hash
▸ make a text file with some text in it
▸ compare with hash of plain text

59. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ Hash
▸ == and === are not timing safe comparisons
▸ Nuances with PHP == returning true
var_dump(md5('240610708') == md5(‘QNKCDZO'));
var_dump(md5('aabg7XSs') == md5('aabC9RqS'));
var_dump(sha1('aaroZmOk') == sha1('aaK1STfY'));
var_dump(sha1('aaO8zKZF') == sha1('aa3OFF9m'));
var_dump('0010e2' == '1e3');
var_dump('0x1234Ab' == '1193131');
var_dump('0xABCdef' == ' 0xABCdef');

60. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ Hash - Coding time!
▸ 15 minutes
▸ hash_equals as a timing safe hash comparison
▸ run thousands of iterations, look for patterns with averages
▸ $timeStart = microtime(true); … $timeEnd =
mircotime(true);
▸ array_multisort($timing, SORT_NUMERIC);

61. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

62. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

63. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

64. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ 10 minute break
▸ Lock picking

65. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ CSPRNG

66. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ CSPRNG
▸ Cryptographically Secure Pseudo-Random Number
Generator (CSPRNG)
▸ Part of PHP 7 core
▸ For PHP < 7:
composer require paragonie/random_compat

67. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ CSPRNG - Coding time!
▸ 10 minutes
▸ random_bytes($length)
▸ bin2hex($randomBytes) for human readable version
▸ random_int($min, $max)
▸ PHP_INT_MIN and PHP_INT_MAX

68. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

69. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

70. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

71. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

72. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ Password hashing

73. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ Password hashing
▸ $insecure = md5($password);
▸ Too fast
▸ Brute force
▸ 5f4dcc3b5aa765d61d8327deb882cf99

74. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ Password hashing
▸ Anthony Ferrara RFC in 2012 to simplify password hashing
▸ Use password_hash and password_verfiy (PHP 5.5+)
▸ $current = password_hash($password,
PASSWORD_DEFAULT);
▸ PASSWORD_DEFAULT can change over time, currently is
blowfish, max password length of 72
▸ $isValid = password_verify($password, $current);

75. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ Password hashing
▸ Salt generated automatically
▸ Deprecated as option in PHP 7
▸ Option ‘cost’, target time it takes
▸ password_hash($password, PASSWORD_DEFAULT,
[‘cost’ => 10]);

76. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ Password hashing - Coding time!
▸ 10 minutes
▸ password_hash($password, PASSWORD_DEFAULT, [‘cost’ => 10]);
▸ notice output pattern, repeat for same password, try variations,
different costs
▸ $2y$10$i49TRWieyhYtQ6P.76R5aOwRisUIqnQJxS6tszUobVkGG8bP9/XsW
▸ $2y$ for algorithm
▸ 10 for cost
▸ 22 character salt, varies by algorithm
▸ Hash as the rest

77. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ Password hashing - Coding time!
▸ 10 minutes
▸ password_verify($plaintext, $hash);
▸ password_needs_rehash($hash, PASSWORD_DEFAULT,
$options)
▸ Timing safe check

78. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

79. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

80. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

81. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ mcrypt

82. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ mcrypt
▸ Encrypt and decrypt
▸ Uses libmcrypt, which hasn’t been updated since 2007
▸ Bug fixes and patches
▸ Use libsodium or OpenSSL instead!

83. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ openssl

84. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ openssl
▸ Generate and verify signatures
▸ Certificate Signing Requests (CSR)
▸ Encrypt and decrypt data
▸ Actively supported

85. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ openssl
▸ Private key generation
▸ openssl_pkey_new([$configs]);
▸ openssl_pkey_export_to_file($privateKey, $fileName);
▸ openssl_free_key($privateKey);

86. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ openssl
▸ Configuration defaults to openssl.conf
▸ digest_alg: Digest method to use
▸ x509_extensions: Extensions to use for x509 cert
▸ req_extensions: Extensions to use for CSR
▸ private_key_bits: Bits for private key generation
▸ private_key_type: Type of key
▸ encrypt_key: Export key with passphrase
▸ encrypt_key_cipher: Cipher for key

87. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ openssl - Coding time!
▸ 5 minutes
▸ Private key generation
▸ $config = [‘private_key_bits’ => 2048, 'private_key_type' =>
OPENSSL_KEYTYPE_RSA];
▸ openssl_pkey_new([$configs]);
▸ openssl_pkey_export_to_file($privateKey, $fileName);
▸ openssl_free_key($privateKey);

88. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

89. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

90. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ openssl - Coding time!
▸ 5 minutes
▸ Public key generation
▸ Continue on from private key generation
▸ openssl_pkey_get_details($privateKey);
▸ file_put_contents(‘public.pem’, $details[‘key’]);
▸ Array with keys ‘bits’, ‘key’ (public key), ‘rsa’, ‘type’

91. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

92. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP

93. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ openssl - Coding time!
▸ 5 minutes
▸ Encrypting data with the public key, decrypt with private
▸ $isEncrypted = openssl_public_encrypt($message,
$encrypted, file_get_contents(‘public.pem’));
▸ $isDecrypted = openssl_private_decrypt($encrypted,
$decrypted, file_get_contents(‘private.pem’);

94. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ openssl - Coding time!
▸ 5 minutes
▸ Encrypting data with the private key, decrypt with public
▸ $isEncrypted = openssl_private_encrypt($message,
$encrypted, file_get_contents(‘private.pem’));
▸ $isDecrypted = openssl_public_decrypt($encrypted,
$decrypted, file_get_contents(‘public.pem’);

95. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ cracklib

96. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ cracklib
▸ PECL extension, must be installed
▸ Checks complexity of passwords
▸ Still experimental

97. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ cracklib
▸ crack_opendict(‘/path/to/dictionary’)
▸ crack_check($dictionary, $password)
▸ crack_getlastmessage()
▸ crack_closedict($dictionary)

98. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ cracklib
▸ it's WAY too short
▸ it is too short
▸ it does not contain enough DIFFERENT characters
▸ it is all whitespace
▸ it is too simplistic/systematic
▸ it looks like a National Insurance number.
▸ it is based on a dictionary word
▸ it is based on a (reversed) dictionary word
▸ strong password

99. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ 10 minute break
▸ Find group of up to 4 for games

100. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ libsodium

101. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ libsodium
▸ PECL extension
▸ PHP 7.2 core
▸ modern cryptography library
▸ namespaced as Sodiumfunction_name

102. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ libsodium - Coding time!
▸ 10 minutes
▸ Cryptographically secure randomness
▸ Sodiumrandombytes_buf($numberBytes) with each byte being a
random value between 0 and 255 (bin2hex for readability)
▸ Sodiumrandombytes_random16() for random integer between 0
and 65535
▸ Sodiumrandombytes_uniform($maxPlusOne) for uniformly
distributed random integers between 0 and max

103. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ libsodium - Coding time!
▸ 10 minutes
▸ Secret-key encryption and decryption
▸ $key =
Sodiumrandombytes_buf(SodiumCRYPTO_SECRETBOX_KEYBYTES);
▸ $nonce =
Sodiumrandombytes_buf(SodiumCRYPTO_SECRETBOX_NONCEBYTES);
▸ $ciphertext = Sodiumcrypto_secretbox('test', $nonce, $key);
▸ $plaintext = Sodiumcrypto_secretbox_open($ciphertext, $nonce, $key);

104. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ libsodium
▸ Public-key encryption and decryption
▸ Sodiumcrypto_box_* functions

105. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ libsodium
▸ Much more functionality
▸ Password hashing and checking
▸ Key signing
▸ Message Authentication Code (MAC)
▸ Hashing

106. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ StupidPass

107. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ StupidPass
▸ composer require northox/stupid-password
▸ $stupidPass = new StupidPass;
▸ $isValid = $stupidPass->validate($password);
▸ $stupidPass->getErrors();
▸ new StupidPass($maxLength, $environmental,
$pathToDictionary, $errorText, $options);

108. CRYPTOGRAPHY WITH PHP
ENCRYPTION WITH PHP
▸ StupidPass - Coding time!
▸ 10 minutes
▸ install composer, StupidPass
▸ Try out common passwords, custom dictionary, see the errors
▸ composer require northox/stupid-password
▸ $stupidPass = new StupidPass;
▸ $isValid = $stupidPass->validate($password);
▸ $stupidPass->getErrors();
▸ new StupidPass($maxLength, $environmental, $pathToDictionary, $errorText, $options);

109. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS

110. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Salts
▸ Algorithm costs
▸ Timing attacks
▸ Brute force attacks
▸ Rainbow tables
▸ Max message length

111. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Salts
▸ Increased security for digest if done correctly
▸ Ex: $salt . $password
▸ Pepper debate
▸ Let password_hash generate the salt for you
▸ Different salt per password or message

112. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Algorithm Costs
▸ Default cost for password_hash is 10
▸ Higher cost leads to more processing time
▸ 8-12 is generally a good baseline
▸ Might change depending on hardware available

113. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Timing Attacks
▸ Analyzing timing for algorithms
▸ Time variation for hashing, encrypting, decrypting
▸ Ex: Username not found, no password check attempted
▸ Ex: String comparisons stop after first mismatch
▸ Timing safety built into functions, take same time for
positive or negative match

114. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Brute Force Attacks
▸ Timing attack used to brute force list of usernames
▸ Dictionary attack using dictionary and common
passwords
▸ Take time
▸ Advanced Persistent Threat (APT)

115. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Brute Force Attacks
▸ Countermeasures
▸ Lock accounts, but causes Denial of Service
▸ Add time to each login
▸ Lock by IP address
▸ Vary failed login attempt behavior (Ex: HTTP status,
redirect)

116. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Brute Force Attacks
▸ Countermeasures
▸ Key words in HTML comments (invalid login, bad
username or password)
▸ Security questions
▸ CAPTCHA
▸ Add another factor (multi-factor authentication)

117. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Rainbow Tables
▸ Table with hashes already figured out
▸ Used for hashing that always generates same hash for
an input
▸ Counter with modern algorithms, salts
▸ Common for MD5, SHA1, and other older algorithms

118. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Rainbow Tables
▸ Internet search for the hash
▸ Online hash cracking sites

119. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Max Message Length
▸ Only X characters considered when generating hash
▸ Ex: MD5 max is 128 characters in, 32 hex out
▸ Ex: password_hash max is 72 characters

120. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Identify sensitive data
▸ Determine appropriate encryption
▸ Use cryptography to keep data safe

121. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Cryptography can help minimize damage
▸ Electronic data breaches
▸ Stolen electronic devices
▸ Data transmission

122. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Cryptography cannot help minimize damage
▸ Phishing attacks
▸ Credential theft
▸ Escalation of privileges
▸ DoS/DDoS
▸ Social engineering

123. CRYPTOGRAPHY WITH PHP
CONSIDERATIONS
▸ Security education
▸ Verizon Data Breach Investigation Report
▸ SANS Institution, email digest
▸ Krebs on Security blog
▸ OWASP
▸ BrightTALK

124. CRYPTOGRAPHY WITH PHP
CRYPTOGRAPHY GAMES

125. CRYPTOGRAPHY WITH PHP
CRYPTOGRAPHY GAMES
▸ Groups of up to 4
▸ 11:15-11:20 Instructions and rules, get in groups
▸ 11:20-11:45 Coding time!
▸ 11:45-11:55 Review answers
▸ 11:55-12:00 Closing

126. CRYPTOGRAPHY WITH PHP
CRYPTOGRAPHY GAMES
▸ Get into your groups of up to 4

127. CRYPTOGRAPHY WITH PHP
CRYPTOGRAPHY GAMES
▸ Instructions and rules
▸ Use PHP
▸ Decrypt the data
▸ Record how you decrypted the message
▸ Record plain text answer
▸ Winning team is team with most correct answers

128. CRYPTOGRAPHY WITH PHP
CRYPTOGRAPHY GAMES
▸ Time is up!

129. CRYPTOGRAPHY WITH PHP
CRYPTOGRAPHY GAMES
▸ Answers

130. CRYPTOGRAPHY WITH PHP
CRYPTOGRAPHY GAMES
▸ Conclusion
▸ Leverage PHP cryptography and hashing features
▸ Use modern libraries
▸ Encrypt sensitive information
▸ Hash passwords correctly

131. CRYPTOGRAPHY WITH PHP
QUESTIONS?
▸ Rate on joind.in
▸ https://joind.in/talk/7b305

132. CRYPTOGRAPHY WITH PHP
SOURCES
▸ Merriam-Webster Dictionary online
▸ PHP.net documentation
▸ Virendra Chandak https://www.virendrachandak.com
▸ OWASP
▸ Verizon 2017 Data Breach Investigations Report
▸ https://paragonie.com/book/pecl-libsodium/read/00-intro.md
▸ https://www.cryptologie.net/article/268/how-to-compare-password-hashes-
in-php/
▸ http://blog.ircmaxell.com/2014/11/its-all-about-time.html