Uses
- 128 bits is a common key size for symmetric ciphers in cryptography. It is also the size of Universally Unique Identifiers (UUID) and IPv6 addresses.
- 128-bit processors could be used for addressing directly up to 2128 (over 3.40 × 1038) bytes, which would greatly exceed the total data stored on Earth as of 2010, which has been estimated to be around 1.2 zettabytes (over 270 bytes).
- Quadruple precision (128-bit) floating point numbers can store qword (64-bit) fixed point numbers or integers accurately without losing precision. Since the Intel 8087 (1980), the x86 architecture supports 80-bit floating points that store and process 64-bit signed integers (-263...263-1) accurately.
- The AS/400 virtual instruction set defines all pointers as 128-bit. This gets translated to the hardware's real instruction set as required, allowing the underlying hardware to change without needing to recompile the software. Past hardware was 32-bit CISC, while current hardware is 64-bit PowerPC. Because pointers are defined to be 128-bit, future hardware may be 128-bit without software incompatibility.
- Increasing the word size can speed up multiple precision mathematical libraries. Applications include cryptography.
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