- 2.1 Representing Ordinary Strings
- 2.2 Representing Strings with Alternate Notations
- 2.3 Using Here-Documents
- 2.4 Finding the Length of a String
- 2.5 Processing a Line at a Time
- 2.6 Processing a Byte at a Time
- 2.7 Performing Specialized String Comparisons
- 2.8 Tokenizing a String
- 2.9 Formatting a String
- 2.10 Using Strings As IO Objects
- 2.11 Controlling Uppercase and Lowercase
- 2.12 Accessing and Assigning Substrings
- 2.13 Substituting in Strings
- 2.14 Searching a String
- 2.15 Converting Between Characters and ASCII Codes
- 2.16 Implicit and Explicit Conversion
- 2.17 Appending an Item Onto a String
- 2.18 Removing Trailing Newlines and Other Characters
- 2.19 Trimming Whitespace from a String
- 2.20 Repeating Strings
- 2.21 Embedding Expressions Within Strings
- 2.22 Delayed Interpolation of Strings
- 2.23 Parsing Comma-Separated Data
- 2.24 Converting Strings to Numbers (Decimal and Otherwise)
- 2.25 Encoding and Decoding rot13 Text
- 2.26 Encrypting Strings
- 2.27 Compressing Strings
- 2.28 Counting Characters in Strings
- 2.29 Reversing a String
- 2.30 Removing Duplicate Characters
- 2.31 Removing Specific Characters
- 2.32 Printing Special Characters
- 2.33 Generating Successive Strings
- 2.34 Calculating a 32-Bit CRC
- 2.35 Calculating the MD5 Hash of a String
- 2.36 Calculating the Levenshtein Distance Between Two Strings
- 2.37 Encoding and Decoding base64 Strings
- 2.38 Encoding and Decoding Strings (uuencode/uudecode)
- 2.39 Expanding and Compressing Tab Characters
- 2.40 Wrapping Lines of Text
- 2.41 Conclusion
This chapter is from the book
This chapter is from the book
This chapter is from the book
2.26 Encrypting Strings
There are times when we don't want strings to be immediately legible. For example, passwords should not be stored in plaintext, no matter how tight the file permissions are.
The standard method crypt uses the standard function of the same name to DES-encrypt a string. It takes a "salt" value as a parameter (similar to the seed value for a random number generator). On non-UNIX platforms, this parameter may be different.
A trivial application for this follows, where we ask for a password that Tolkien fans should know:
coded = "hfCghHIE5LAM."
puts "Speak, friend, and enter!"
print "Password: "
password = gets.chop
if password.crypt("hf") == coded
puts "Welcome!"
else
puts "What are you, an orc?"
end
It is worth noting that you should never rely on encryption of this nature for a server-side web application because a password entered on a web form is still transmitted over the Internet in plaintext. In a case like this, the easiest security measure is the Secure Sockets Layer (SSL). Of course, you could still use encryption on the server side, but for a different reason—to protect the password as it is stored rather than during transmission.