ASCII, Unicode, and Text Representation
Understand how text becomes bytes and why character encoding matters in cryptographic contexts.
ASCII as 7-Bit Encoding
ASCII (American Standard Code for Information Interchange), standardized in 1963, encodes 128 characters in 7 bits (values 0-127). It covers the English alphabet (upper and lowercase), digits, punctuation, and control characters.
ASCII was designed for English and American telecommunication equipment. It worked well for its intended purpose but was fundamentally inadequate for any language beyond English.
Control Characters in ASCII
The first 32 ASCII characters (0-31) plus DEL (127) are control characters. They were originally designed for controlling Teletype machines: LF (line feed, 10), CR (carriage return, 13), BEL (bell, 7), TAB (9), ESC (27).
In cryptographic contexts, control characters can cause problems. A null byte (0x00) terminates C strings early, and a DEL or ESC character might be interpreted by terminal emulators.
All lessons in this course
- Base64 Encoding: How It Works
- ASCII, Unicode, and Text Representation
- Hexadecimal in Cryptographic Output
- Encoding vs Encryption vs Hashing