<h1>Mifare Classic 1K Rewritable UID: A Comprehensive Guide</h1> <h2>Understanding the Mifare Classic 1K Rewritable UID Card</h2> The <strong>Mifare Classic 1K rewritable UID</strong> card represents a specialized variant of the ubiquitous MIFARE Classic contactless smart card. In my experience working with access control systems, the ability to rewrite the UID (Unique Identifier) on these cards has been both a powerful tool for legitimate system integration and a point of security consideration. My personal skill in RFID prototyping was significantly enhanced when I first learned to properly handle these rewritable cards, moving beyond standard read-only tags. <h3>Technical Specifications and Parameters of Mifare Classic 1K Rewritable UID</h3> For developers and integrators, understanding the precise technical metrics is crucial. Below are the detailed parameters for a typical <strong>Mifare Classic 1K rewritable UID</strong> product. *Please note: These technical parameters are for reference data; specifics need to contact backend management.* <h4>Detailed Product Parameters</h4> * **Chip Type:** NXP MF1ICS50 derivative or compatible clone chip with UID rewrite functionality. * **Memory:** 1Kbyte EEPROM, organized in 16 sectors, each with 4 blocks (64 blocks total, 16 bytes per block). * **UID Length:** 4-byte (default) or 7-byte UID capability. The UID block (Block 0) is rewritable, unlike standard Mifare Classic cards. * **Communication Frequency:** 13.56 MHz. * **Data Retention:** Up to 10 years. * **Read/Write Cycles:** Typically 100,000 cycles for EEPROM. * **Operating Temperature:** -20°C to +50°C. * **Standard Dimensions:** ISO/IEC 7810 ID-1 format, 85.6mm x 54.0mm x 0.84mm. Alternative formats like key fobs (often 30mm x 40mm x 4mm) are also common. * **Communication Protocol:** ISO/IEC 14443 Type A. * **Special Function:** UID, SAK, and ATQA can be rewritten using specialized tools and commands, bypassing the factory-locked state. My opinion is that while the technical flexibility is impressive, it fundamentally alters the security premise of the MIFARE Classic platform, which originally relied on a hard-coded, unique factory identifier as a root of trust. <h3>Practical and Entertainment Applications</h3> The <strong>Mifare Classic 1K rewritable UID</strong> finds use in various scenarios. A common entertainment application is in customizing amiibo figures for Nintendo consoles, where users can write specific character data onto a rewritable tag. Furthermore, they are used in prototyping and testing access co